Stair Riser Tread Ratio

Or use the handy chart below with the ratios already figured for you.

Stair riser tread ratio.

Minimum 10 inch stair tread depth with nosing or minimum 11 inches with no nosing. At stair riser specifications and at stair dimensions width height you ll read that stair risers should be 7 inches 178 mm maximum and 4 inches 102 mm minimum. The ratio for exterior stairs is two risers the tread 26 inches. Having the right calculations before getting started can make the task a lot easier.

Rise r 12 run r 4 r r 16 too low 2r r 28 too high won t be comfortable. Treads the tread depth b should not be less than 10 inches 254 mm. Fortunately the stair is used primarily for storage. The rise or height of a step is measured from the top of one tread to the top of the next tread.

Handrail graspability to be either type i or ii with a minimum 1 1 2 inch clearance from a wall. In a given run of stairs the greatest tread depth should not exceed the smallest by more than 3 8 inch 9 5 mm. Staircase calculation formula is total required number of risers total stair rise height of one rise 60 6 10 riser total required number of tread total stair tread or run width of one tread 90 10 9 tread. You ll find the tread width in the column on the left and the rise height in the column on the right.

To simplify the process we ve created this deck stair calculator to help you determine the correct measurements needed to carry out your project. The r r then was 16 too low and 2r r was 28 too high. The optimum riser for exterior stairs is 6 1 2 inches making the tread 13 inches wide. We would need change the stair tread depth to make a 37 slope stair that has an acceptable 7 inch riser height.

Handrail height to be placed a minimum 34 inches to 38 inches. Typically a single 2x12 or two 2x6s are used for stair tread material. Step tread 2 riser 26 or 27. Building stairs for your deck is often considered the most difficult part of the construction project.

Maximum 7 3 4 inch stair riser height. A riser higher than 7 inches is not recommended outside though interior stair dimensions can be higher than that. It is not the physical height of the riser because this excludes the thickness of the tread. Aside from the treads being too small for safety the rise would have been about 12 and the run about 4.