| The maximum stair
riser variation for a stairway is 3/8 of an inch.
Again, this one can be tricky to interpret, and I'm going to do my best.
The maximum variation from the bottom riser to the top can't be more
than 3/8 of an inch on any individual stair riser. Remember, these are
finish stair riser measurements, not rough framing riser measurements.
Attention: Don't forget to check with your local
building department to verify any building codes on this website. This
information could be incorrect or outdated. Building codes are updated
regularly and to some building departments have different
interpretations for certain building codes.
You can't average out the riser measurements either.
You take the smallest riser measurement and then try to find a largest
riser in the stairway, it can't be more than 3/8 of and inch larger than
the smallest one.
Four Step Stairway Example 1: The bottom riser is 7 inches, the second
riser is 7 inches, the third riser is 7 inches, the fourth riser is 7
inches but the fifth riser is 7 1/2 inches. There is more than 3/8 of an
inch variation and this particular stairway wouldn't pass most building
inspections.
Four Step Stairway Example 2: The bottom riser is 7 inches, the second
riser is 7 - 1/8 inches, the third riser is 7 inches, the fourth riser
is 7 - 1/4 and the fifth riser is 7 1/4 inches. This stairway would be
acceptable by most building departments.
Four Step Stairway Example 3: The bottom riser is 6 3/4 inches, the
second riser is 7 inches, the third riser is 7 inches, the fourth riser
is 7 inches but the fifth riser is 6 3/4 inches. Again the variation
isn't more than 3/8 of an inch and this particular stairway shouldn't
have a problem passing most building inspections.
The reason why building departments allow for variations in your
stairway risers are simple. It's hard to cut and install a perfect set
up stairs without small riser variations. Large riser variations greater
than 3/8 of an inch are unacceptable, but smaller ones can be tolerated.
This building code gives stair builders a little room for errors made
during construction, variations in building materials sizes and lumber
expansion and shrinkage.
Stair Tread Minimum
Stair
Tread Nosing Requirements
Floor and
Landing Overhang
Closed Treads and Open Risers
What's an Open Riser
Staircase?
Problems with Open Risers Stairways
Minimum Stair Clearance
Painted Riser For
Safety
Stair Guard Railing |
