Check Measurements On Plans If Architect Is Using Maximum Building Code Riser Heights
This discusses a potential discrepancy between stair riser heights specified in building plans and the actual measurements required to meet local building codes. The information is aimed at home builders, contractors, and anyone who assembles stairs based on architectural plans.
The Problem: Rounding Off Riser Heights to Meet Building Code Minimums
The core issue arises when architects design stairs with minimal space available. In such scenarios, they might round off riser heights upwards to fit the stairs into the designated space while ensuring the overall rise meets the building code minimum. This rounding off can create problems during construction when builders rely solely on the measurements provided in the plans.
Building codes typically specify minimum riser heights. Most codes allow a 7.5 or 7.75 inch riser height in buildings with less than 50 occupants.
The problem is when the architect wants to maximize the number of risers within the available space. They might divide the total rise by one fewer riser than what's ideal. For instance, dividing the 105-inch total rise by 13 risers would result in a riser height of 105 inches / 13 risers = 8.076 inches.
The architect might then round this number down to 8 inches to meet the building code minimum. This rounding off, however, creates a discrepancy of 0.076 inches per riser. While this might seem insignificant, multiplying it by the number of risers (13 in this example) yields a total difference of 0.98 inches, or almost 1 inch.
Key Takeaways
Don't solely rely on the riser heights specified in plans, especially if the architect is using maximum allowable building code measurements.
Double-check the total rise and individual riser heights by calculating them yourself based on the framing dimensions provided in the plans.
Ensure the calculated riser heights comply with your local building codes.
If discrepancies arise, consult with the architect or engineer to ensure the stairs meet code requirements and maintain structural integrity.
By following these steps, home builders and contractors can avoid construction delays and ensure their stairs are built to code specifications.
