One reason that it's better to use screws rather than nails on any home-improvement project is that screws are stronger and also have greater holding power. Screws are also a good idea if you're assembling something that may need to be taken apart. In general, wood screws are ideal for home repair jobs. While most wood screws are made out of steel, it's better to use copper, brass, bronze or nickel screws for jobs where there's a risk of corrosion.
If you need to link pieces of metal as part of your project, you'll want to use sheet metal screws. As these screws are installed in the metal, they begin to form treads. There are several types of sheet metal screws to choose from. For light sheet metal, it's recommended that you use pointed panhead screws. For projects that involve heavier sheet metal, blunt panhead screws are the way to go. Machine screws also connect metallic parts to one another. This type of screw is usually made out of either brass or steel. In order to prevent rust from setting in, machine screws are coated with cadmium, brass, nickel, copper or zinc. Machine screws come in one of four head types: roundhead, flathead, ovalhead and fillister-head. If you're taking on a really heavy-duty project, you'll want to use roundhead screws, which can be used on either hard or soft metals. Roundhead screws are suited for work that involves thick sheet metal.
If your home improvement job includes fastening to wood framing or masonry, you'll want to use lag screws. Since larger jobs need more holding power, lag screws, as well as lead expansion anchors, are the way to go.