Sealing the Exterior

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Builders often refer to the exterior of a home as the "envelope" or the "shell." Sealing the envelope or shell against air infiltration (air leaking into the house from outside) and air exfiltration (air leaking from inside the house to the outside) helps reduce your energy expenditure for space heating and cooling. Besides, no one likes to live in a drafty house.

In this article, we'll show you a variety of ways you can seal leaks and improve insulation to make your home cozier and more energy efficient. Once you've sealed and insulated the weak areas, the work doesn't stop there. We'll show you how routine cleaning and water conservation can increase energy efficiency and save you even more money on your energy bills. Begin the improvement process with the following basic sealing guidelines to help you secure your home's exterior.

Testing for Leaks

Technicians use a "blower-door test" to accurately measure air leakage in houses. The test involves sealing a portable, frame-mounted fan in an exterior doorway to the house. Any known openings to the outside, such as the fireplace flue; bathroom vent fans; and the flues to the water heater, furnace, or boiler are temporarily sealed.

After the sealing and setup is complete and the blower fan is switched on, it is possible to measure with precision how much air is entering the house through all the various "unintended" cracks, gaps, and holes in the exterior envelope. Using devices called smoke pencils, technicians can pinpoint areas where air is entering the house while the blower door is in operation.

While every home is different and each has its own set of leakage points, there are areas where infiltration shows up repeatedly in blower-door tests. These often include the seam between the top of the foundation wall and the wood framing that runs above, around, and through doors and windows; along baseboards; through electrical receptacles and switches mounted on exterior walls; and around fireplaces, laundry chutes, attic hatchway doors and pull-down stairways, whole-house fan installations, and pipe and wire chases. A homeowner can go a long way toward increasing energy efficiency by locating and sealing up as many of these entry points as possible.

You don't necessarily need to have a blower-door test done on your home in order to locate the unsealed areas that are leaking air. Knowing that these points of air entry have been routinely and consistently identified in other houses gives you a start on where to look for gaps and cracks in yours. A windy day outside can be helpful in this endeavor. Wind can push air into the house through unseen and unnoticed holes to the point that you can feel the air movement.

Checking Exterior Sheathing

Before plywood and oriented strand board (OSB) were invented, homes were built entirely with solid board lumber. The exterior was sheathed underneath the siding with wide boards that, over time, shrank and cracked. All these cracks -- and the many others inherent in most homes -- are pathways through which air can enter or leave a house. Sidewall sheathing is covered with siding, so all those cracks that appear in and between wide boards on older homes are hidden and inaccessible.

Air enters the sheathing through cracks in the siding; around windows and doors; and through other openings in the exterior envelope that include kitchen and bathroom vent fan louvers, dryer vents, holes bored for air-conditioning lines, electrical and gas service wires and pipes, along the underside of the lowest course of siding, and through other holes. Any time you can find and seal a crack on the exterior of a house, you go a long way toward reducing air infiltration and exfiltration on the inside.

Because of the large size of plywood and OSB sheets, there are relatively fewer seams in the sheathing on newer homes. And the use of products like house wrap on new construction has further reduced air infiltration. Consequently, most new homes are more airtight than older ones. But although the sheathing might be more airtight in a newer home, there are still many places where air is getting in and out. Finding and sealing those leakage points not only reduces drafts and energy usage, but it also helps keep out insects and other pests.

Filling Holes Around Lines

HVAC system installers need to bore a large hole through the exterior wall of the house in order to pass refrigerant lines through to the compressor outside. Most take time to caulk the hole around the lines, but the caulk fails over time, often leaving a gap where air (and insects) can infiltrate the house. A few minutes spent with a caulk gun will close the gap and shut off the flow of outside air into the house.

Caulking the Exterior

Some people find that once an older home has been freshly painted, they suddenly feel warmer or "cozier" inside during the winter. That may be because the painter who worked on the house took time to caulk cracks, gaps, and other holes in the home's exterior "skin." While minute gaps around doors and windows might not seem as though they could possibly add up to much, under certain conditions it is surprising how much air they can let into and out of a house.

Consider a windy day. Wind drives air into gaps and around obstructions. Add rain to the mix, and you've got the recipe for both water and air infiltration. So caulking pays off in regard to both energy savings and building preservation. That's why you don't need to wait until it's time to paint to caulk visible openings on the exterior of your house.

Securing the Perimeter

The wooden framing in most homes rests on top of a solid concrete or concrete block foundation. In homes built before 1980 or so, the lowest section of wood, called the "mud sill," rests directly on top of the concrete. While the connection is secure from a strength standpoint, in terms of eliminating air infiltration, things could be much better. The problem is the rough and variable surface of the top of the foundation wall. While there are many areas where the wood presses down tightly, other areas may leave a gap through which wind can enter.

The gaps, which collectively might add up to a hole the size of a basketball in the exterior envelope, can usually be sealed with either caulk or cans of spray foam. This procedure, which can be done either on the inside or outside of the house (depending on which offers the best access) requires that you first brush away the dirt and cobwebs from the concrete and wood so the caulk or foam will stick to both surfaces.

From that point on it's just a matter of aiming the caulk tube's tip or spray foam applicator tube at the gaps and gunning them full of caulk or foam. It's a job that doesn't have to be neat or precise, just thorough. Once you're finished, you will have stopped up one of the leakiest places in the home.

In newer homes, the gap between the mud sill and the top of the foundation wall is filled with a thin, compressible length of foam material. The foam creates an airtight seal that does not need remedial caulking or foaming. However, it's worth checking along this area anyway, as occasionally the foam sealer didn't get placed exactly where it should have been. Also, the top of the foundation wall might be too uneven for the foam to fill the gap, someone might have forgotten to put it in place, or it might stop short of the corners. In any of those cases, a shot of caulk or foam can quickly remedy the problem.

In the next section, we'll discuss some basic sealing techniques you can use indoors to help make your home more energy efficient.

Sealing the Interior

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Once the exterior of the home is sealed as well as possible, it is valuable to do the same to the inside as well. Below are some basic guidelines on areas you can secure to keep heat and air conditioning from escaping.

Baseboards and Floors

Gaps are often left between baseboards and hard floors, such as tile, hardwood, or laminate flooring. These gaps can be successfully and neatly filled with latex caulk, thus preventing air from entering the home at foot level.

Gaskets Can Block Drafts

Wind can sneak in through tiny gaps and cracks that you don't even know are there. Often, the first time you're aware of such a problem is when you flick a switch or plug an electronic device into a receptacle mounted on an exterior wall. Not only does the switch or receptacle feel cold, but it's sometimes possible to actually feel a cold draft blowing into the room.

You can block many of these types of drafts from inside the house by purchasing and installing inexpensive switch and receptacle gaskets from a hardware store or home center. The gaskets, made of nonelectrically conductive fiber matt material, fit snugly around the switch or receptacle after the cover plate is removed. With the gasket in place the standard cover plate goes back on, creating an airtight seal against the wall. For the cost of just a few cents each, gaskets are a worthwhile investment in energy saving and comfort.

Caution: To avoid electrical shock, you should remove cover plates from switches and receptacles only after power has been shut off at the main service panel to the circuits where work is being done. Other than that, each gasket installation will require about two minutes of your time.

A Canister of Trouble

Recessed ceiling canister lights pose special problems for a homeowner bent on making a home more energy-efficient. The older types are extremely leaky and are difficult to make airtight. Because of regulations concerning fire safety, the best you can do is to build an airtight box of flame-resistant material -- sheet metal, for instance, or drywall -- at least three inches larger than the light's housing to cover the portion of the fixture that is in the attic. This box can then be sealed to the drywall. It cannot be covered with insulation, however, as heat buildup inside the fixture could cause problems with the wiring inside.

Heat generated by the bulbs inside recessed canister lights is usually lost to the attic and doesn't contribute to heating the house. This excess heat flowing unchecked into the attic space can cause problems with ice dams on the roof during the winter.

Another solution to older, leaky canister lights is to replace the fixtures entirely with new airtight units. "ICAT" (insulation contact, airtight) canister lights are the most energy-efficient recessed canister lights on the market.

As the name suggests, they are airtight and can also be covered with insulation. To further improve their performance, airtight ceiling canister lights can also be sealed to drywall or plaster with caulk. When you calculate the cost of allowing heat to escape through a leaking ceiling canister light, the cost it takes to replace it with a more energy-efficient model is easy to justify.

Attics and the Stack Effect

The floor of an attic is an important battlefield on the energy conservation front because of a phenomenon known as the "stack effect."

Warm air rises. That much is nearly universally known; it is the reason hot air rises up a fireplace flue or "chimney stack." What isn't so commonly recognized is that rising warm air creates pressure at the top of whatever is containing it. In a household situation the top-floor ceiling acts as a containment barrier to rising warm air. As such, any small hole or gap in that area is subject to pressurized warm air trying to escape.

Warm air loss due to the stack effect has another consequence. As air exits through the top-floor ceiling or other holes, it creates a slight negative pressure inside the house. The air leaving has to be replaced, and that air comes from outside the house: cold, dry air. The incoming air has to be heated, and that's when your furnace or boiler comes on.

Up the Flue

Builders occasionally run into difficulty framing and sealing an opening around a fireplace. There needs to be clearance between the wood and the masonry or metal, so the framing can't fit tightly against those materials. That means the finish wall material -- usually drywall or plaster -- is supposed to bridge the gap for fire safety and also provide an airtight closure. Comprehensive sealing in this area, however, can sometimes be neglected. In some cases that means there are gaps around fireplaces that allow air to leave the house easily.

Take time to look inside and around fireplaces with a good flashlight to see whether there are any holes and gaps that need to be sealed with spray foam, fireproof caulk, or other filler material. Not only will this reduce the amount of air leaving the house via these pathways, but it can also protect areas from sparks or embers leaping out of a fire.

Weatherstripping around doors can help keep drafts out of your house, which can keep your heating and cooling bills under control. In the next section, we'll discuss how to better secure your doors.

Weatherstripping Doors

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While windows attract most of the attention when it comes to energy efficiency, doors can play a major part in what can go wrong -- or right. Doors have a particularly difficult role to fill. Not only do they need to open and close smoothly and easily, but they also have to seal tightly to keep out drafts, and must have at least some insulative value to keep cold at bay.

There are many different options on the market that can be used to upgrade a door's existing weatherstripping. Some of the most effective are types that contain a vinyl bulb or padded strip set into the edge of a conventional wood doorstop. The wood part is nailed to the doorjamb and is flexible enough to conform to even a badly warped wooden door. The vinyl bulb or strip seals out air movement, but is gentle enough that the door's function is not affected.

Other types of weatherstripping include thin bronze or brass strips that are nailed inside the jamb where the door closes. Small nails are driven along one edge of the stripping while the other edge is sprung outward slightly. When the door closes, it contacts the metal strip, bending it a bit and ensuring tight contact with the door edge. This type of weatherstripping is time-consuming to install correctly, but it lasts for years and is an effective draft stopper.

Foam tape is usually ineffective as door weatherstripping. Even the thinnest foam tape is too bulky to fit along the edge of the doorstop, and if applied in this area, it causes the door to bind and not shut properly. Foam tape is also not durable enough for everyday use in this type of application and soon fails, falling off the doorstop or tearing.

Some contractors are equipped to install a type of vinyl bulb weather stripping that is cut into the door frame with a special tool that resembles a router and cuts a small groove into the intersection of the doorstop and the jamb.

A barbed fin on the vinyl bulb weatherstrip is pressed into the groove, and friction keeps it there. This type of weatherstripping is very effective if installed properly, but the hard part is finding someone who has the equipment and know-how to install it.

Door Sweeps and Adjustable Thresholds

While weatherstripping takes care of weatherizing the top and sides of a door, there's still one edge left to deal with -- the threshold. And it's a tough area to address; thresholds accumulate grit and dirt and are subject to a lot of wear and tear. Manufacturers have come up with dozens of solutions to the problem of stopping drafts at the threshold level. Some replacement thresholds are complicated to install. They may require removing the door or even cutting off the bottom of the door. Others are easier to install but don't last long in extreme environmental conditions.

Instead of ripping out the entire old threshold and replacing it with something new, you may consider installing door bottoms or door sweeps. Door bottoms attach to the bottom of a door and can be adjusted to lightly graze the existing threshold as the door closes.

Door sweeps attach to the inside of the door near the bottom edge -- the door does not have to be removed -- and consist of a brush or pad that contacts the edge of the threshold as the door shuts. Some doors have a spring-loaded mechanism that snaps the sweep material down as the door closes and retracts it when the door opens, thus creating clearance under the door for an entryway mat. All of these products depend on careful installation to be effective.

On particularly difficult doors to seal, it is worth considering installing a door bottom as well as a door sweep. Much of the draft that gets by the first line of defense will be stopped by the second.

Some doors have adjustable thresholds, but few homeowners make the effort to adjust them as time, settlement, and wear take their toll. It's a good idea every now and then to get down on your hands and knees on the inside of the house in front of an entry door, press the side of your face to the floor, and look at the area where the threshold is supposed to come into contact with the bottom edge of the door. Often you'll see a wide gap; that's where air can breech the door's line of defense.

Adjustable thresholds are usually made from wood or aluminum (sometimes both), and the adjustable part is covered with a removable, replaceable strip of vinyl. After removing the vinyl, you'll see several large screw heads. Those are the adjustors. By tightening or loosening the screws, you can cause the center, adjustable part of the threshold to rise or fall. You'll have to use trial and error to determine how far up or down to move the adjustable portion, but it's worth it to get it right. Once the vinyl strip is back in place, you should not be able to see light coming under the door, and there should be just a little resistance or drag as the door bottom passes over the threshold. If you raise the threshold too far and create too much drag, both the door bottom and the vinyl strip will wear out prematurely.

Older doors equipped with vinyl door bottoms and adjustable thresholds may suffer from torn or worn parts. While some generic replacement parts are usually available at hardware stores and home centers, the best bet for a perfect match is to contact the original manufacturer of the door.

Storm doors, like storm windows, can add draft-stopping ability, insulation, and protection to a home's entry doors. The better the installation and the tighter the fit of a storm door, the more effective it will be. Aluminum storm doors have frames that screw to the outside of the door casing. There might be gaps between the frame and the casing, and those can be filled with caulk.

Another area of potential air infiltration is the door bottom. Most storm doors have an adjustable door bottom that can slide up or down once the screws holding it in place are loosened. This adjustability allows the door bottom to fit snugly to the door's threshold.

There is usually a vinyl strip that seals the storm-door bottom to the edge of the threshold, and those sometimes get torn or worn out. Replacements are available but are sometimes difficult to track down. Similarly, the weatherstripping that is attached to the frame and contacts the face of the door as it closes must also be in good condition for the storm door to function as it was designed.

The Right Storm Door

Storm doors can add draft-stopping ability, insulation, and protection to a home's entry doors. The better the installation and the tighter the fit of a storm door, the more effective it will be. Aluminum storm doors have frames that screw to the outside of the door casing. There might be gaps between the frame and the casing, and those can be filled with caulk.

Another area of potential air infiltration is the door bottom. Most storm doors have an adjustable door bottom that can slide up or down once the screws holding it in place are loosened. This adjustability allows the door bottom to fit snugly to the door's threshold.

There is usually a vinyl strip that seals the storm-door bottom to the edge of the threshold, and those sometimes get torn or worn out. Replacements are available but are sometimes difficult to track down. Similarly, the weatherstripping that is attached to the frame and contacts the face of the door as it closes must also be in good condition for the storm door to function as it was designed.

When a storm door is properly sealed and adjusted, it will make the prime door on the house slightly difficult to close. With no other place to go, air trapped between the two will have to rush out around the sides, top, and bottom as the prime door shuts. And when opening the prime door, the storm door should suck in slightly as air is pulled out of the area between the doors. When that happens, you know you've done just about everything that can be done to make a storm door as effective as possible.

Heat and air conditioning can also escape from windows that aren't properly fitted or just old. In the next section, we'll talk about techniques to make your windows more energy efficient.

Sealing Windows

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Owners of older homes that still have their original windows are often dismayed by the amount of cold air leaking through those old windows during the winter. There are several ways of dealing with this problem that don't involve a lot of time or money.

One option involves using a caulk gun and "weatherstripping caulk sealant" or "temporary" caulking to seal up the cracks between the window and window frame. Weatherstripping sealant is caulk that is designed to stick in place nearly as well as regular caulk but can be peeled off when it is no longer needed. It is available inexpensively in regular caulk tubes and comes in a clear color. It is nearly invisible when in place and removes easily without damaging either paint or clear finishes.

One drawback to temporarily caulking windows is that once the caulk is in place, the window can't be opened without destroying the seal. This could pose a problem if, for instance, there is a day when you'd like to open the windows to take advantage of a warm breeze. Of course, you could peel the caulk off and then reapply it when the weather turns cool again. But it's better to wait until you're sure there will be no more warm days.

Several lightweight plastic, disposable, interior "storm window systems" are also on the market and are effective in keeping out cold drafts and increasing the insulative value of a window assembly. These kits consist of double-stick tape that is applied to the trim casing around the window, and lightweight plastic sheeting that is pressed onto the tape. Once the plastic is in place, a hair dryer is blown across the surface of the sheeting, causing the plastic to shrink and remove the wrinkles. Like caulking windows shut, this system is best used once you're pretty sure you won't be opening the windows for a couple of months.

While plastic interior storm window kits are effective in helping to prevent heat loss through windows, they are noticeable and might look out of place in formal areas of your home.

Storm Windows

Storm windows can play a key part in your energy-saving plans. They act as a wind buffer, and the air trapped between the storms and the prime windows acts as insulation. In addition, storm windows protect the prime windows from the weather, which can extend the time between paint jobs required on the house.

Older homes are often equipped with heavy wooden storm windows that need to be put up in the fall and taken down in the spring when they are usually replaced with wooden-framed screens. Newer options, and a worthy upgrade to wooden storm windows, include permanently installed aluminum or vinyl storms, which self-store the window glazing and screens. Instead of lugging large storm windows up and down a ladder twice a year, you can simply open each prime window from the inside and slide the glazing or screen portions up or down. This reconfigures the storm window depending on the season.

Many people choose to remove the lightweight screen portion of the storm window during the winter, preferring to look only through window glass instead of screening.

Not only is the window glass more aesthetically pleasing, but without a screen in place sunlight can also shine more directly into the house, allowing you to benefit from solar heating.

Another advantage to having storm windows installed on your house is that the extra layer of glazing cuts down on neighborhood and traffic noise. And storms keep out dust and dirt that otherwise might filter in through leaky prime windows.

Securing windows isn't enough to block drafts. It's also important to check how well your sidewall insulation is holding up. We'll show you how in the next section.

Sidewall and Garage Insulation

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Homes lose heat through their sidewalls. Many older homes, built before sidewall insulation had been invented or perfected, are candidates for this upgrade. Measured in square footage, the sidewalls in most houses represent the largest exposure of any area to the outdoors. So it makes sense to make them as resistant to heat flow as possible.

Several different materials can be used for sidewall insulation: cellulose fiber, fiberglass, and a number of different types of foam. Each will not only retard heat flow from the inside of the house to the outside but will also cut down on air infiltration through gaps in the sheathing and other areas. Some foam products can be injected into sidewall cavities even if there is already insulation in place.

While sidewall insulation can be installed from inside the house through holes drilled into plaster or drywall, the usual protocol is to do it from the outside. This tricky job is best left to the experts.

Injection holes can be drilled through wooden clapboard siding and then plugged with paintable plastic caps, or some lengths of the siding can be removed and then replaced after holes have been drilled through the sheathing. Holes in stucco-sided homes can be patched with stucco-cement materials, and vinyl and aluminum siding can be temporarily removed and then replaced after the insulation-installation process is complete.

The Garage and House Interface

Homes with attached garages often have "interface" problems that can lead to waste of heat and cooling. Because the garage is attached to the house, in many cases the effort that goes into insulating the outside of the house against the weather is not extended to the garage. That's a mistake, because in the winter the garage can become just as cold as the outdoor air -- and in the summer, even hotter than it is outside.

There are often holes in garage walls, either put there intentionally or accidentally, that allow air movement between the two areas. Not only are these potential pathways for heated or cooled air to escape or infiltrate, but they are also a danger.

The shared wall between a house and garage is required to be fire-rated. That's so a fire that starts in the garage will be contained there for as long as possible before it breaks through to the house. Garage fires are more common than many people think; car batteries develop short circuits, and gasoline is often stored in cans for use with lawn mowers and other yard maintenance equipment. A hole in a wall between a garage and house can compromise fire safety.

There is another hazard that can involve a leaky shared garage and house wall. That has to do with carbon monoxide. An automobile produces a tremendous amount of carbon monoxide gas, especially when its engine is cold, as it is when first starting up. If you start your car in the garage in the morning and then pull it outside, shutting the garage door traps a large volume of carbon monoxide inside. This deadly gas can leak or be pulled into the house if there are pathways in the shared wall that allow it to infiltrate.

The solution is to make every effort to seal up areas where air might be able to pass between the house and garage. Prime locations are the bottom of the wall inside the garage and the bottom of the doorway into the house. There is a juncture between the framing and concrete where the bottom of the wall meets the concrete foundation that is similar to the one around the perimeter of the rest of the house. This location sometimes lacks a layer of compressible foam between the two materials that would provide an airtight seal. Caulk or foam applied either inside the basement (as previously described in the section on sealing this seam) or in the garage can effectively seal the gap.

It is also worth using caulk or foam to seal the bottom edges of the drywall to the concrete. The reason? In negative pressure situations, air can be drawn into this crack or into the stud cavities inside the wall, and then it can enter the house via an electrical receptacle in that wall inside the house. For instance, negative pressure can occur when the kitchen vent fan is running. That forces air out of the house, and as a result the atmospheric pressure inside the house decreases. The pressure seeks to equalize by drawing air into the house through any opening it can. If the path of least resistance happens to be that crack along the bottom of the garage/house wall, the incoming air can bring carbon monoxide along with it. Adding gaskets to receptacles on both sides of the wall also helps in keeping contaminated garage air out of the house.

The door into the house from the garage is often a leak point as well. Caulking around all the trim and an examination of the door's weatherstripping to ensure that it is intact will help block off this potential air passageway. Frequently used doors like the one from the garage into the house might need repair or replacement more frequently than do other entry doors.

Attics are another prime area where homes lose heat. Over time ice dams can form on your roof and cause damage. In the next section, we'll discuss how that process happens and what you can do to prevent it.

Eliminating Ice Dams

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If you have ice dams forming on your roof during the winter, it means that heat is escaping the house and leaking into your attic. Ice dams are the manifestation of energy inefficiency in a home. They are the result of poor air sealing, a lack of insulation, and inadequate ventilation in an attic.

Warm air travels upward because of its natural buoyancy. As it reaches the ceiling in the top floor, it seeks ways to rise even higher through cracks and gaps in the ceiling and walls. Some of those pathways are obvious; many others are not. Openings around and through recessed canister lights, whole-house fan installations, attic-access hatchways and pull-down stairs, and electrical boxes in the ceiling and walls all provide conduits from the house into the attic. Additionally, heat is conducted upward through the top-floor ceiling through inadequate attic floor insulation. The result of the air leaks and conducted heat is an accumulation of warm air in the attic.

When snow falls on top of a roof, it acts as insulation, protecting the roof surface from the outside cold air. The combination of heat from below and snow on top creates conditions that warm the roof sheathing and shingles.

The warm shingles melt the snow that covers them, and that water runs down the roof, under the snowpack that lies on top of the roof. As the water reaches the roof edge, there is no longer any heat from below to warm the shingles and sustain the melting process. The water freezes along the overhangs and starts to build into ice dams.

As the ice dams build up higher over the course of the winter due to the constantly melting snow on the roof, water starts to form ponds behind the dams. Eventually, if the water level gets high enough and if the roof is inadequately protected from water intrusion, it starts to seep in underneath the shingles. In the worst cases the water can penetrate into the soffit areas, get behind the siding, and even enter the house through the interior ceilings and walls. Ice dams can be very destructive and result in millions of dollars in insurance claims every year.

The root cause of ice dams is excess heat in the attic. Air sealing and upgrading insulation will help reduce the heat leakage problem. The idea is to make the attic as cold as possible -- as cold as the outside air -- to reduce or eliminate the snow melting that starts the ice dam formation process. Additional ventilation in the attic also exhausts any heat that does manage to make it up there.

The ideal ventilation scheme involves several components: soffit vents that introduce air into the attic under the eave edges; air channels; chutes that hold insulation back from the underside of the roof sheathing and direct the air upward from the soffits into the attic; and high roof or ridge vents that convey the air to the outdoors. The chutes are important because insulation lying against the underside of the roof sheathing forms a thermal bridge that allows heat from the house below to travel through the insulation directly to the sheathing. It is essential to break that thermal bridge to eliminate the direct conveyance of the heat to the sheathing and to promote the free flow of air into the rest of the attic from the soffit vents.

Attic ventilation is also needed to reduce moisture concentration in the attic environment. Air that travels into the attic from the house below carries water vapor. Unless that moisture is vented away, it can condense on the cold insulation, framing, and sheathing. If allowed to continue, the wet surroundings can create conditions conducive to mildew and mold growth, and can even rot.

Adequate attic ventilation also pays off in the summer. Air flowing through the soffit vents and up through the ridge or high roof vents exhausts heat. Venting the attic means less heat is transferred downward through the attic floor insulation and into the house below. Therefore, the A/C doesn't have to run as often, which conserves your energy dollars.

Comprehensive air sealing, insulation, and ventilation can reduce or eliminate the formation of ice dams on your house roof in the winter while paying dividends in the summer.

If you aren't sure how or where to check your attic for leaks, we'll share tips on how you can find and seal those weak areas in the next section.

Attic Sealing and Insulation

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Most every attic has at least some insulation in it, and that's fine. Insulation helps prohibit heat loss. It doesn't stop airflow, however, and that's a problem. The insulation lying on attic floors often conceals a very large problem -- cracks, gaps, and holes through which pressurized air from the house below is driven into the attic.

These fissures take many forms: holes drilled into the wood framing where wiring runs from a room below up into the attic; lighting fixtures and electrical boxes; areas where the tops of partition walls in the room below intersect with the attic-floor framing; bulkheads over kitchen and bathroom cabinets; exhaust vent fans; and fireplace and heating equipment chimneys and flues. It's a long list, and it's likely you can find fissures in your own attic that aren't even mentioned.

Every one of these holes represents an opportunity for warm air to escape the rooms below -- and that escaping air represents your energy dollars flying up and away as well. So, although digging through insulation in the attic to find and seal up these trouble spots is probably not anyone's idea of fun, it is time well spent.

The materials used for sealing most attic floor penetrations are caulk and spray foam. The application does not have to be neat; no one is going to come along and grade you on tidy performance. Once you foam or caulk, you'll just cover the area with insulation again. But it will behoove you to do a thorough job. Remember, any gap left unfilled will leak air.

Sealing Leaks

In an attic filled with unfaced fiberglass insulation, it's relatively easy to find spots where air is leaking upward from the rooms below. You'll often see gray, brown, or black smudges or staining in the insulation. Those discolored spots are dirt that was borne on the air leaking from below. Fiberglass insulation strains contaminants out of the air and leaves them there as telltale indicators of air leakage. Lift up the fiberglass batting at one of these spots, and you'll find an opening into the rooms below, maybe an electrical box or wire chase.

Attics insulated with cellulose fiber don't show air-leak smudges. The material is as dark as most airborne dirt, and it doesn't act as a filter. So you'll need to use your sleuthing skills to come up with places likely to contain room ceiling/attic floor penetrations. Examine rooms below before you enter the attic. Take note of where light fixtures and interior walls are located. You may even want to draw a map.

Once you locate a hole that needs to be filled, use a brush to sweep the insulation back, squirt caulk or spray foam to seal the hole or gap, replace the insulation, and move on to the next spot.

Be especially aware that many interior walls have wires running up into the attic. Foam around the wires to fill the holes in the framing. Electrical boxes should have the power switched off before you work around them. Caulking around the box where it penetrates the drywall or plaster and around the wires that run into the box will seal things as well as possible. Vent fan housings can be sealed in a similar manner.

Chimneys require a different approach. Building codes now mandate at least a two-inch gap between any flammable material (usually wood framing) and the masonry or metal. In newer homes this gap is sometimes left unfilled, leaving a hole that goes directly from the basement to the attic. A lot of warm air can rush up a hole that size. Older homes may not have as sizable a gap, but the solution for either is to close the hole with a nonflammable material and fireproof caulk. Sheet metal nailed to the framing and shoved against the chimney works well, and it can be sealed with the caulk to eliminate any of the remaining small gaps.

Securing Pull-Down Attic Stairways

A pull-down attic stairway probably represents the largest hole in the attic floor -- a hole through which a tremendous amount of air can flow in both winter and summer. Some energy experts estimate that the gap around a typical pull-down stairway system can amount to 40 square inches. You'd certainly notice if there was a hole that size in your ceiling, but many people don't connect a pull-down attic stairway with a loss of heat or cooling.

The undersides of many pull-down attic stair units is made of 1/4-inch plywood that warps away from its sealing surfaces shortly after installation. Springs that hold the stairway in place lose their resilience over time, allowing the unit to sag down from the opening and further open gaps between the plywood and the jamb. And even in the best of circumstances the entirety of the stair system is uninsulated. It's a worst-case scenario in terms of air sealing and energy efficiency.

Sealing a pull-down attic stairway is tough to do. The stairway, after all, still has to function as an entrance and exit. But adding compressible self-stick foam tape along the upper edges of the plywood door can help reduce air leakage. Adding eyehooks or another type of latching device to the door causes it to jam tight against the foam weather stripping when not in use.

A more comprehensive solution is to insulate the door as well as adding air-sealing capabilities. Several kits are available to solve this dilemma. One is called an "attic tent." It consists of a clothlike material that is caulked and stapled to the framing around the stairway opening. A zipper in the upper part of the tent can be opened for access and closed for air sealing after use. The stairway opens and closes normally underneath the tent fabric. An attic tent, however, provides only a small measure of insulative value compared to the insulation that should be on the rest of the attic floor.

Another kit version is a thick, insulated box that surrounds the stairway opening in the attic. It comes with a removable cover, which can be lifted off when access to the attic is desired, and sealing strips along the bottom of the box that contact either the framing around the stairway or the attic floor. Such a box could also be constructed by a homeowner using rigid foam board and other easily obtainable materials.

If your current attic insulation is getting old or needs to be changed, the next section will discuss how you can make an upgrade.

Upgrading Attic Insulation

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These days most attics don't have enough insulation or have insulation that isn't working as well as it should be. An upgrade -- one that will pay off every year and in every season you live in your home -- is only one messy afternoon away. Yes, you can and should add more insulation to your attic. It's one of the best ways to increase your home's energy efficiency.

R-factor is a numerical indicator of an insulation's efficiency at retarding the flow of heat. The scale goes from low to high; higher R-numbers mean a given insulation is better able to stop heat from moving from one place to another. Current building codes recommend an insulation R-factor of R-38 for attics in most of the country. That would be about 10 to 12 inches of fiberglass batting or blown cellulose fiber insulation. Bear in mind that R-38 is actually the minimum recommended standard for attic insulation. Proposed energy codes would increase that number to R-50.

Fiberglass and cellulose fiber are the two most common attic insulation materials. Each yields an R-factor of roughly 3.5 per inch. Cellulose consists of ground-up newspaper material, which is then treated with fire-retardant chemicals. Fiberglass is made of billions of strands of extruded glass fibers packed into specifically sized batts. Some fiberglass batting now comes encased in perforated poly bags to help contain loose glass fibers and make handling and installation easier. Fiberglass also is available as a loose-fill or blown-in material.

While it is possible to do a good job fitting and installing fiberglass batting around all the many framing members and other obstructions in an attic, it is somewhat rare to see such a thorough installation. Many homeowners and insulation installers either don't understand the importance of tightly fitting the material into the many spaces that abound in an attic or find the job too tedious to do correctly. Usually there are gaps and holes between batts and between batts and framing. Those holes defeat much of the insulative value the material can provide.

Cellulose fiber, on the other hand, because it is ground into a fine material, flows and can be blown into all the attic's nooks and crannies, allowing it to do a better, more comprehensive insulation job. And nearly any determined homeowner can do it. Home centers that sell insulation of all types even loan insulation blowers to customers who buy a certain number of bags from their stores. Information on how to operate the machines and install the insulation is available in those stores and from manufacturers.

Cellulose fiber insulation is also less subject than open fiberglass to what builders call "wind wash," which is simply air currents moving through insulation, robbing it of its R-value. Fiberglass batts that are enclosed in perforated poly bags are less subject to wind wash than are either open batts or loose-fill fiberglass insulation.

Any type of attic insulation can be installed over any other type: fiberglass over cellulose, cellulose over fiberglass -- it makes no difference. The fiberglass must be unfaced, however, or encased in perforated poly bags. Otherwise, condensation could develop on the facing.

If your attic has a floor and is used for storage, the potential insulation depth is limited by the depth of the floor joists. Thus, many attics could have a substandard R-factor of only 20 or so -- unless you go to the trouble of removing the floor and adding additional framing lumber to the tops of the joists and then reinstalling the floor.

An easier solution than floor removal is to consolidate the stored items into a smaller area (or remove them from the attic entirely), and roll out poly-encased fiberglass batting on top of the floor. The batts can be removed or rolled back at any time if the space is required for storage in the future.

While the price of fuel oil, gas, and electricity continues to rise, attic insulation is relatively inexpensive and remains one of your best energy-efficiency upgrade values.

Energy efficiency isn't just about sealing and insulating your home. Dust collecting on appliances and irregular maintenance of heating and cooling equipment wastes energy. Check out how to head off these problems in the next section.

Cleaning and Maintenance

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Once you have your home properly sealed and insulated, your work isn't done. Homeowners willing to get their hands dirty with cleaning and minor maintenance tasks can improve their home's energy efficiency. Below are some guidelines on how periodic cleaning can add up to saving you money.

Cleaning Refrigerator Coils Regularly

The coils underneath and behind a refrigerator are dust magnets. Refrigerant is pumped and circulated through the coils as a fan blows room air across them. The moving air removes heat from the refrigerant inside the coils. As the fan sucks air from underneath the refrigerator, it brings along with it dust and dirt that stick to the coils. Removing the access panel from the lower front of the refrigerator can reveal a startlingly filthy sight if the coils haven't been cleaned in a while.

In addition to being unsightly, the dust on the coils acts as insulation that prevents the fan from efficiently removing heat. Cleaning the refrigerator coils a couple of times a year with a vacuum cleaner and an elongated brush helps the refrigerator operate at its maximum efficiency. Moving a refrigerator away from a wall so air can circulate behind it will increase its energy performance, as will keeping it out of direct sunlight and away from heat sources like a radiator or a range.

As energy-saving tips go, cleaning the coils under your refrigerator probably produces little economic effect compared to the amount of effort required to do the job. But it's still a task worth undertaking, if only for the hygienic benefit.

Replacing the Furnace Filter

The filter on a forced-air furnace performs a valuable function in the home. It strains bits of dust, dirt, and debris from the air stream as it passes through the furnace. This not only improves air quality, but it also protects the inside of the furnace (and air-conditioning evaporator coil, if there is one). Without a furnace filter in place, dirt would build up on the back side of the heater exchanger and inside the evaporator coil. That dirt would act as insulation and interfere with the efficient transfer of heat from the furnace or cooling from the air conditioner to the air passing through it.

But a furnace filter also slows the passage of air through the furnace -- especially when it is dirty. The best way to keep your furnace operating at its maximum efficiency is to keep a clean filter inside. That's one of the only things you as a homeowner can do to maintain your furnace.

Filters can be purchased in bulk and replaced every 30 to 45 days, or they can be vacuumed at those same time intervals. People who own pets may find that their furnace filters need to be replaced or cleaned more frequently, due to pet dander, hair, and dirt brought in from outside.

It is important to remember that in most homes that have a central air-conditioning system, the furnace's blower is used to distribute cool and dehumidified air during the summer months. Therefore, air passes through the furnace -- and the furnace filter -- during those months as well. That's why homeowners with central air-conditioning systems need to change or clean filters in the summertime at roughly the same intervals as they do during the winter. The more freely air can pass through the furnace, the more heat and cooling it can distribute while wasting less energy.

Tuning Up Heating and Cooling Equipment

Furnaces, boilers, and air-conditioning systems all have mechanical, moving parts in addition to electrical components. Over time these parts can go out of adjustment and need lubrication and cleaning. Like an automobile, your heating and cooling equipment runs best when it is "tuned up" and all the parts are working together as they were designed.

Tuning up heating, ventilation, and air conditioning equipment, especially the newer, more complicated systems, should be attempted only by service people who have the training and the equipment to do the work. How often should you call for service? For oil-fired systems, the recommended interval is a year. Gas-fired furnaces and boilers and air-conditioning systems should be checked at least every two years.

Just as tuning up a car can yield better gas mileage, the money you spend on servicing your HVAC equipment will pay off in better efficiency -- and will also extend the life of the components.

Removing Dirt From Baseboards

Hot water baseboard and electric baseboard heating systems run at maximum efficiency only if the baseboard convectors and radiators are kept clean. These systems depend on air flowing through the many fins that surround the pipes or heating elements. Obstruction of that air -- either from dirt and dust buildup or from something covering the top or bottom of the heating units -- compromises the performance of the entire system. As is the case with a forced-air furnace, freely flowing air contributes to better efficiency and energy conservation.

Removing or opening the covers that surround baseboard convectors exposes the fins that distribute heat from hot water inside the pipes or heating elements. Vacuuming and brushing the fins, and straightening any that are bent, ensures efficient airflow -- and thus efficient heat transfer to the air.

Checking Ducts for Leaks

Duct sealing: Keeping ducts clear of dirt will help heat and air conditioning flow properly to all rooms. Scheduling an annual service cleaning also will provide an opportunity to check for leaks. Here's a startling statistic: Professional heating, ventilation, and air-conditioning organizations estimate that 25 percent of the air traveling down a poorly installed forced-air duct system winds up somewhere other than where it was intended to go. In other words, some duct systems leak 25 percent of the air passing through them. That leakage might occur in basements, crawl spaces, duct chases, or attics. The bottom line is that you're not getting all the heating and cooling for which you are paying.

The solution to leaky ducts is duct sealing. While it is tempting to use a product called "duct tape" to do this job, regular duct tape is actually poorly suited for duct sealing. The adhesives in cloth duct tape break down in the presence of heat; eventually the tape fails and falls off the duct.

A product better suited for the task is duct-sealing mastic, available in tubs at heating supply houses, hardware stores, and home centers. To apply duct mastic, dip a gloved hand into the tub, scoop out some mastic, and smear it all around every single joint you can find in your ductwork. The mastic has the consistency of pancake batter, and once it cures it stays on the duct and doesn't leak.

There are plenty of opportunities in most forced-air heating and cooling systems to upgrade the performance of the ducts. Loosely fitting joints and gaps large and small also should be sealed as soon as possible.

After a sealing job is complete, diverter vanes inside the ducts (if they are installed) might have to be rejiggered and cleaned because air that was supposed to go to a certain area will finally be doing so. The result might be that a formerly cold room is suddenly the warmest one in the house. Also, the furnace or A/C compressor might not come on as often once the conditioned air is getting to where it was designed to go. Duct mastic is inexpensive, the time it takes to seal up your ducts is minimal, and the results can be dramatic.

Duct wrappers: After duct sealing is complete, it's time to think about upgrading your forced-air delivery system even further.

Any ducts passing through unheated crawl spaces or attics should be insulated. Heat and cooling thrown off by the ducts in such areas is completely wasted, but if that heat and cooling were retained, the furnace or air conditioner might not have to work so hard to condition the house.

Duct insulation is available in both wrapping and sleeve types. Sleeves are more effective because they have fewer seams, but may require temporary disassembly of the ducts in order to slip them into place.

Maintaining a Clear Path for the Air Conditioner

Air-conditioning systems work by moving refrigerant from inside the house to outside. Inside the furnace evaporator coil, the refrigerant absorbs heat from the air passing through the blower compartment. The refrigerant is then pumped outside and flows into a heat-transfer assembly called the condenser. The condenser coils resemble an automobile's radiator. As refrigerant flows through small tubes in the condenser coils, thin metal fins attached to those tubes extract heat from the refrigerant.

A fan inside the condenser moves air past all the tiny fins and tubes, accelerating the transfer of heat from the refrigerant to the outside air. But this cooling flow of air can take place only when the pathways to the compressor are unobstructed. Landscape plantings, ivy, decks, or benches built over and around the compressor restrict the free flow of air through the system, reducing its efficient transfer of heat. So, to get the most for your A/C dollar, it's a good idea to keep the outside compressor unit cleared of nearby obstructions.

Because airflow through the condenser is important for the efficient function of a central air-conditioning system, carefully examine the outside of the condenser unit from time to time. The thin metal fins are fragile and can bend if something comes in contact with them -- a baseball, lawn mower tire, or edge of a rake, for example. "Fin combs" are inexpensive at heating supply stores and home centers, and they can straighten several rows of bent fins at once.

Cleaning and minor maintenance aren't the only steps you can take around the house to help improve energy efficiency. In the next section we'll talk about strategies for more effective water conservation.

Water Conservation

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Improving water conservation in your home can help you save not just on water bills, but also on expenses for heating water. Below are some ideas you can try to boost your water conservation efforts.

Removing Sediment Buildup

Draining sediment from a water heater's tank is an energy-saving procedure anyone can do quickly and easily. Periodically removing accumulated sediment helps conventional water heaters operate at optimum efficiency. The sediment consists of hard-water minerals and other debris that enter the storage tank along with the incoming water. As the water is heated, the minerals separate from the water and fall to the bottom of the tank.

Over time, the mineral deposits build up to the point that they act as insulation on the bottom of the tank, isolating the water from effects of the burner firing below (on gas and oil units) and sometimes stacking up high enough to cover the heating element on electric water heaters. The harder it is for heat to get through the sediment layer, the longer the burner has to fire or the electric elements have to run in order to heat the water.

The solution is to remove the sediment layer. You do not have to turn off the power source (electricity, gas, or oil) to the water in order to drain the sediment.

A small drain valve is on the outside of the water heater tank's jacket near the bottom. It looks like a miniature hose bibb on the outside of a house. Attach a short length of standard garden hose to this valve, stick the free end of the hose into either a floor drain nearby or a large bucket, and open the valve.

Water will flow from the bottom of the water heater and out the valve and through the hose, taking sediment along with it. After draining five gallons or so from the tank, shut off the valve, disconnect the hose, and empty the bucket (if you used one) into a sink or toilet. You've not only improved the efficiency of your water heater, but you've also extended its service life.

What is the reason? There is a thin film of water that is trapped between the sediment and the bottom of the tank. When the burner fires, the thin layer of water heats to an abnormally high temperature that deteriorates the tank's glass lining, speeding up its rusting process. Accumulated sediment is also responsible for the popping, banging, rumbling, and percolating noises often heard from a water heater as the burner fires or the elements heat up.

Depending on the mineral content of your water, a water heater tank should be drained of its sediment at least twice a year, and more often in hard-water areas.

Insulating Pipes

What does pipe insulation do? It keeps heat inside the pipes where it belongs, rather than radiating out into the air. The result is that hot water reaches distant bathrooms faster than it would otherwise, reducing the volume of water that has to flow down the pipe for hot water to effectively arrive. And once hot water fills the pipe, it stays there for a long time. So if you use a hot water tap again shortly after the first usage, it's likely that the water will still be sufficiently hot.

In addition, pipe insulation helps reduce "standby" heat losses at the water heater. Standby heat losses occur while the water heater is just sitting there doing nothing at all. Over a period of time, heat radiating from the water heater's tank and the pipes entering and exiting the top of the unit reduce the temperature of the water inside the tank. Eventually, the thermostat is activated and the burner fires or the electric elements switch on. The water heats up again, only to cool down gradually through the cooling effects of the tank and pipes. It's an endless cycle, exacerbated by the heat loss through the pipes at the top of the water heater. So, although the hot water pipes are the logical ones to insulate, insulating the first five feet or so of the cold water pipe at the water heater is a good idea, too. That helps reduce the loss of heat that migrates up the pipe from the water heater tank.

Although insulating the pipes at the water heater might eliminate only one burner firing or element activation a day, at today's gas and electric prices, that can add up to substantial savings over the course of a year.

It may also be worthwhile to insulate another cold water pipe in your house -- the water service entry pipe from a municipal supply or well -- though not for energy-efficiency reasons. Throughout the winter and into the spring, water coming into the house through that pipe is cold. If the air is humid enough, condensation can form on the outside of the pipe and drip down onto carpets, suspended ceiling tiles, and anything else along its path. Covering the exposed pipe with foam insulation isolates the pipe from the humid air, preventing condensation from forming.

Insulating water pipes used to involve a large roll of itchy fiberglass insulation, a lot of time, and a lot of cutting and fitting the wrapping around obstructions. And even after all that work, the insulation was so thin that it didn't do much good. Insulating the water pipes in your home these days is simpler, quicker, and more effective.

The closed cell foam pipe insulation available at plumbing supply houses and home centers not only insulates far better than the old fiberglass material, but it's also easy to install. Each piece is slit along its length, allowing the insulation to simply snap over the pipe. The foam is so soft that it can be cut with a kitchen knife or a pair of heavy scissors.

Adding a Blanket to the Water Heater

New water heaters are being built with better insulation these days, so if you have an old unit, don't be shy about adding an extra layer of insulation. There are water heater "blankets" available at home centers and hardware stores that wrap the exterior of the unit with an additional layer of insulation.

Electric water heaters can be covered top to bottom with insulation. Gas water heaters, however, must not be covered on top or along the bottom. The top contains the flue, and that can get hot enough to ignite flammable materials. The bottom must be left open so air can enter the burner assembly for proper combustion of the natural gas, propane, or oil.

The end of the pressure and temperature relief valve extension pipe (usually running down the side of the unit) on any type of water heater must be left open and exposed as well. This pipe has to be free of obstructions in case the valve activates and releases hot water or steam. Any blockage could interfere with the free release of the pressure within the tank, and that could be dangerous.

Other than that, the more insulation you can wrap around a water heater, the fewer "standby" losses will occur, the less the burner or elements will come on, and the more efficient it will be overall. This is a relatively easy and inexpensive task that pays off every hour of every day from the moment you put the blanket on. Like most jobs involving insulation, it's not glamorous, but it works.

Installing Reduced-Flow Showerheads

Nearly half of all water used in a home is used for bathing. Almost all of that water needs to be heated. Therefore, the bathroom is an ideal place to practice energy and water conservation. Since January 1995, showerheads in new homes have been required to dispense no more than 2.5 gallons per minute. If you have a showerhead older than that in your home, it takes but a few minutes to replace it with a showerhead that meets the modern flow rate standards.

Showerheads aren't expensive. Ten to twenty-five dollars will purchase a new one that meets the 2.5-gallon limit. If you have an older showerhead that allows up to 6 gallons a minute and subsequently install a low-flow showerhead, you'll reduce your shower water use by more than three gallons per minute.

Water entering a home in northern states in the winter can be as cold as 38 degrees. Heating water that cold to the 120 degrees or so needed to produce a reasonably hot shower demands quite a bit of energy. So it's easy to understand why taking advantage of 2.5-gallon showerhood technology can save a lot on your utility bill.

A caveat though: Putting a low-flow showerhead into use is not an excuse to spend more time in the shower. In some cases, the length of time a person spends in a shower is exactly equivalent to how long the hot water in the water heater's tank lasts. Once the hot water runs out, the shower is over. If it took, say, ten minutes to exhaust your water heater's capacity with a six gallon per minute showerhead, does that mean you can now stay under the running water for 20 minutes with a reduced-flow showerhead in place? Technically, yes. But that would result in no energy or water savings. If you confine your shower activities to simply washing, rinsing, and then getting out, keeping the shower's length the same as it was before the introduction of the new showerhead, you'll decrease your use of energy and water.

Using Faucet Aerators

Older-style bathroom and kitchen sink faucets can deliver as much at 3.5 to 5 gallons of water per minute. Much of that water is wasted; typical washing tasks can usually be accomplished using less.

Faucet aerators, either supplied on new faucets or as inexpensive retrofit add-ons to older faucets, reduce the flow rate to 0.5 to 1.0 gallon per minute in bathrooms, and 1.0 to 2.0 gallons per minute at the kitchen sink. Because air is added to the water stream at the faucet's tip, the flow seems full although the actual volume of water is substantially reduced. This allows you to do more with less hot water.

Leaks, poor insulation, and unproperly cared for appliances or equipment allow heat and air conditioning to escape from your home. The guidelines in this article give homeowners ways to take control and minimize those weak areas.

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