Slope on Stair Treads and Landings

by Sean O'Hara on December 2, 2014

I received an email today from an individual who’s contractor had built an exterior concrete stair for them. Each tread sloped 3/4″ down from back to front. I quickly emailed them back to let them know that isn’t up to code and in fact is quite dangerous. If those treads get wet or icy it could lead to a bad fall.

The International Building and Residential Codes state “The walking surface of treads and landings of stairways shall be sloped no steeper than one unit vertical in 48 inches horizontal.” In a 12″ deep tread that’s only 1/4″ of outslope.

In an interior stair the treads are generally going to be flat but in an exterior application it makes sense to have a small amount of slope for drainage.

Originally posted 2011-05-19 10:41:43. Republished by Blog Post Promoter


{ 4 comments… read them below or add one }

Sean O'Hara May 21, 2015 at 9:31 am

Sure, just email us at and we’ll see what we can do.

Sean O'Hara May 15, 2015 at 2:13 pm

Can you clarify “in N”?

uncle jr May 11, 2015 at 6:26 pm

Slope on Stair Treads

OK I like 3/16 max when I do outside concrete treads.

But is there a code saying you need pitch on treads in N??

Thomas May 6, 2015 at 8:54 am

I need stairs or stair design for exterior wood stairs rising to 108 1/2″. There will be a landing at approximately 35″=-.
Can you help?

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