Say your porch is 3 feet (1 meter) high. Following the steps above, here’s how your calculations would work out:
- Take 36 inches (91 cm) and divide by 7 inches (18 cm) to get 5.14 steps. Round to the nearest whole number, meaning your staircase should have five steps.
- Take 36 inches (91 cm) and divide by five steps to get 7.2 inches (18.2 cm), your actual riser height.
- Based on the chart, the 7 ¼ inch (18 ¼ cm) riser height means the run width should be 11 inches (28 cm).
Your porch then should have five steps, each 7 ¼ inches (18 ¼ cm) high and 11 inches (28 cm) wide.
Designing Porch Stairs
We've all been frustrated by poorly designed staircases. Steep, narrow basement steps make everyone nervous. Or maybe you've been annoyed by excessively squat and wide marble steps in historic buildings. Attempting to fit a staircase into too small or too long an area can result in stairs that feel awkward to use. That's something you definitely want to avoid with your homemade stairs. Fortunately, a porch stairs project doesn't cause so many headaches -- you should be able to build them out to the proper place, instead of having to fudge the numbers so a basement connects to the ground floor.
Designing a staircase isn't about scallops and flourishes on the railings. It's about figuring out the correct number of stairs.
To design your stairs, follow these steps:
- Measure the rise of your future staircase in inches (or centimeters) and divide by 7 inches (18 cm), the ideal step height, to find the number of steps.
- Divide your porch height (or total rise) by your number of steps to find out how high each riser should be. Round to the nearest quarter inch (quarter centimeter).
- The rise height determines the run width. Find a chart like the one here to determine your run width based on your step height [source: DoItYourself].
If you made it through all that math and your head's still on straight, then step on over to the fun stuff -- the actual building of the porch stairs.