Stairs - Risers and Treads


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The "2016 California Residential Code, Section R.311.7" requires a maximum  7-1/4" riser height and a minimum 10" tread depth. 

 

I've seen some recent plans with steeper stairs.  What are the code requirements for your location?

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7 minutes ago, DRAWZILLA said:

I'm pretty sure you don't need the 5/8" type "x" under anymore.

you're right..heres crc 2016 (current as of writing):

BUILDING PLANNING

2016 CALIFORNIA RESIDENTIAL CODE

73

R302.7 Under-stair protection.

Enclosed accessible space under stairs shall have walls, under-stair surface and any soffits protected on the enclosed side with 1/2 -inch (12.7 mm) gypsum board.

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1 hour ago, DRAWZILLA said:

I'm pretty sure you don't need the 5/8" type "x" under anymore.

 

If that’s true, that seems really dumb.  They’re adding ridiculous requirements all the time and then they go and remove one that actually makes sense?  Stairs have always needed extra protection to make sure they remain standing as long as reasonably possible in the event of a fire.  I wonder what the logic was in removing such an easy-to -adhere-to safety requirement.

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8 hours ago, Francois said:

I also use a thumb rule that is "2 risers + 1 thread =~ 27"" when risers are low or threads are deep. Great for decks or walkway steps

I've always use the same rule but with a range of 24"-28". 

 

The problem however is that with 7-3/4" risers the formula would allow 9" treads. 

Fortunately the code requires 10" minimum treads but even that can result in a pretty steep stairway.  A lot of condo builders use 7-3/4" / 10" which I find uncomfortably steep.

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In MA it's 8.25" rise and 10" finished run.  So they cut the stringers to 9" and with the overhang it's 10".  With the stud height / floor joist depth most residential stairs are usually in the 7 7/8" - 8 1/8" range.  If you add another tread it will bring it down to 7 5/8" or so.

 

With all the antique homes here it's not unusual to go into a home with 8"-9" rises or more. 

 

Commercial of course is quite a bit different.

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9 minutes ago, Jay_on_Cape said:

So they cut the stringers to 9" and with the overhang it's 10".

That's actually 8"R/9"T with a 1" nosing.  It was allowable for private stairs in the UBC and for existing homes that would generally be grandfathered with the current IRC - but only for existing stairs. 

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3 minutes ago, Joe_Carrick said:

That's actually 8"R/9"T with a 1" nosing.  It was allowable for private stairs in the UBC and for existing homes that would generally be grandfathered with the current IRC - but only for existing stairs. 

In MA they still let you get away with 8.25".....

 

See page 16.  We use the 2015 IRC in MA and anything they want changed they address it in their codebook with corresponding code number to pertinent IRC # (or IBC if commercial). 

 

https://www.mass.gov/files/documents/2018/06/08/Chapter 3 Building Planning Amendments.pdf

 

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On 6/18/2019 at 9:18 AM, Renerabbitt said:

here's a staircase detail i drew up;

staircase detail.calibz

Capture.thumb.PNG.0be888d8d0d15827b68296e165e62c2e.PNG

 

Good job.  I think it may be more clear on headroom if

the clearance included what we used to call the tangent

 

Tweaked version, 

1517398665_newstaircasedetail.thumb.PNG.3115d73ad9daa2285996e86397cd7e14.PNG

 

Also, not sure 7' required at landing.

 

Headroom.thumb.PNG.dcbb04dbf1bb883d83cf2940a5c1d4b7.PNG

 

Anyway, thank you for sharing the detail.

 

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Indiana...

The maximum riser height is 7 ¾ inches; all risers must be within 3/8” of each other.

 

The minimum tread depth is 10 inches, with a 1-inch nosing. A nosing is not required where the tread depth is 11 inches. All treads must be within 3/8” of each other.

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On 6/18/2019 at 9:49 AM, DRAWZILLA said:

I'm pretty sure you don't need the 5/8" type "x" under anymore.

 

I believe only 1/2" gyp bd is required under stairs and on walls between the house and the garage......  but....

 

You still need 5/8" type x on walls supporting a second floor in the garage as well as on the ceiling/floor of the second floor room over garage.......  the 5/8" is only required on the garage side of the common wall between the house and garage.

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