How do I figure out stair treads and risers?
Can I measure in inches and use a Calculator?
Q: I am building a wooden deck and have a general idea about how to build stairs. I want to get each step and riser to be exactly the same, but my calculator does not convert decimal numbers to fractions. I want to experiment with different sizes, please help.
A: If your calculator does not convert to inches, or fractions of inches, use the chart below, and follow these easy steps.
- Measure total rise from ground to top of landing.In this example we will use 3'6" rise.
Check local building codes for maximum heights, minimum requires specifications, etc.
- Measure from edge of landing out total distance where you would like bottom landing to be.For this example we will use a 5'6" total distance from landing to landing.
Top landing may be the edge of a deck, a doorway, or an actual landing step. Bottom landing may be the edge of a walkway or any point away from structure where bottom of stairway will end.
Check local building codes to see if landing area specifications exist -- some stairways must end or begin within set distances from other structures, entrances, etc.
- Determine the size of the treads you'd like to have.Typical residential exterior steps use 11" treads and 7" rises. So lets start experimenting just using the 11" tread and see how the math works.
Most building codes require minimum and maximum tread widths and will provide formulas for proper ratios of tread to rise.
- Divide the total distance by the tread size.5'5" = 66"
66" / 11" = 6 (treads)
If total distance out from top edge of landing is 66" and you want 11" treads, this would result in 6 steps of 7" rise, which would fit exactly in a 42" high total rise.
3'5" = 42"
42" / 7" = 6 (risers)
To experiment with different size treads and rises, use a calculator and the chart below for common 1/4", 1/8", 1/16" or even 1/32", and 1/64" sizes depending on the materials you are working with and the degree of accuracy you require when cutting materials.
Take this example for instance:
Total Rise: 49 7/8"
Total Distance: 71 3/4"
71.75 / 11" = 7 (treads)
49.875 / 7 = 7.125" (or 7 1/8") rises.
Experiment with various sizes until measurment falls within desired range of accuracy.