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-   -   Stair riser height (http://www.diychatroom.com/f19/stair-riser-height-164362/)

Akomjati 11-22-2012 07:13 AM

Stair riser height
 
I'm finishing the basement and putting 2 inch foam insulation on the floor while also adding cement board and radiant heat wire burried in self-leveling compount followed by ceramic tiling. This will bring the floor height by roughtly 3 inches. I have stairs from the first floor to a landing where a 180 degree change takes place. I'm planning on replacing the stairs from the landing to the basement floor. Due to this 3 inch difference between the landing height from the first floor and basement floor, can I make the riser height different for the bottom set of steps than the top set of steps. Don't want to do a complete new stairs and landings.

oh'mike 11-22-2012 07:19 AM

I fixed that little & quote thing---There are several stair masters here--and some other members with an answer---one will be along soon---Moderator----

BigJim 11-22-2012 09:50 AM

How much difference are you talking about? All of my stairs were build and very few were for correction, although many were restores, so I really can't say for sure. Hopefully Keith or Millertyme will drop in and let us all know.

I know if I were doing the job it all would have to come out and be a do over.

I am a little concerned at how you explained your basement floor. Are you using the cement board as structural, or are you installing a plywood or other subfloor over the insulation? If you plan to use the cement board as a subfloor only you may have problems.

joecaption 11-22-2012 09:58 AM

Not a great plan, tile is never going to hold up with a subfloor done that way.

sixeightten 11-22-2012 10:42 AM

I think you are permitted to change the height at a the landing. I think only 1/4" is acceptable though. Sounds like you will have more than that. I would change the entire stairs/landing.

kwikfishron 11-22-2012 10:43 AM

Quote:

Originally Posted by Akomjati (Post 1058161)
Due to this 3 inch difference between the landing height from the first floor and basement floor, can I make the riser height different for the bottom set of steps than the top set of steps. Don't want to do a complete new stairs and landings.

You can if the difference in rise is no more than 3/8".

This guide should help. http://www.precisionstairsystems.com...copy_1__1_.pdf

kwikfishron 11-22-2012 10:47 AM

Quote:

Originally Posted by sixeightten (Post 1058248)
I think you are permitted to change the height at a the landing.

I don't think so but I sure would like to know the definitive answer to that.

Gary in WA 11-22-2012 12:12 PM

If under the IRC, a "flight" of stairs is defined as: "FLIGHT. A continuous run of rectangular treads or winders or combination thereof from one landing to another. " From: http://publicecodes.cyberregs.com/ic...2.htmUnderline is mine.

The risers can change height between flights but not vary individually by 3/8": "R311.7.4.1 Riser height. The maximum riser height shall be 73/4 inches (196 mm). The riser shall be measured vertically between leading edges of the adjacent treads. The greatest riser height within any flight of stairs shall not exceed the smallest by more than 3/8 inch (9.5 mm)."

The treads can change depth, but vary by only 3/8" also; "R311.7.4.2 Tread depth. The minimum tread depth shall be 10 inches (254 mm). The tread depth shall be measured horizontally between the vertical planes of the foremost projection of adjacent treads and at a right angle to the tread's leading edge. The greatest tread depth within any flight of stairs shall not exceed the smallest by more than 3/8 inch (9.5 mm). Consistently shaped winders at the walkline shall be allowed within the same flight of stairs as rectangular treads and do not have to be within 3/8 inch (9.5 mm) of the rectangular tread depth. "

Which leaves us with the all-important nosing (IF required, that remains the same at all flights between stories, if I understand this correctly);
"
R311.7.4.3 Profile. The radius of curvature at the nosing shall be no greater than 9/16 inch (14 mm). A nosing not less than 3/4 inch (19 mm) but not more than 11/4 inches (32 mm) shall be provided on stairways with solid risers. The greatest nosing projection shall not exceed the smallest nosing projection by more than 3/8 inch (9.5 mm) between two stories, including the nosing at the level of floors and landings. Beveling of nosings shall not exceed 1/2 inch (12.7 mm). Risers shall be vertical or sloped under the tread above from the underside of the nosing above at an angle not more than 30 degrees (0.51 rad) from the vertical. Open risers are permitted, provided that the opening between treads does not permit the passage of a 4-inch diameter (102 mm) sphere.

Exceptions: 1. A nosing is not required where the tread depth is a minimum of 11 inches (279 mm). 2. The opening between adjacent treads is not limited on stairs with a total rise of 30 inches (762 mm) or less." Underline is mine, from: http://publicecodes.cyberregs.com/ic...?bu2=undefined
Check locally with your AHJ.
Gary
P.S. Guide and definitions; flights-"Drawing 9", definitions- pp.18; http://www.abqstair.com/wp-content/u...copy_1__1_.pdf

BigJim 11-22-2012 12:56 PM

Quote:

Originally Posted by GBR in WA (Post 1058294)
If under the IRC, a "flight" of stairs is defined as: "FLIGHT. A continuous run of rectangular treads or winders or combination thereof from one landing to another. " From: http://publicecodes.cyberregs.com/ic...2.htmUnderline is mine.

The risers can change height between flights but not vary individually by 3/8": "R311.7.4.1 Riser height. The maximum riser height shall be 73/4 inches (196 mm). The riser shall be measured vertically between leading edges of the adjacent treads. The greatest riser height within any flight of stairs shall not exceed the smallest by more than 3/8 inch (9.5 mm)."

The treads can change depth, but vary by only 3/8" also; "R311.7.4.2 Tread depth. The minimum tread depth shall be 10 inches (254 mm). The tread depth shall be measured horizontally between the vertical planes of the foremost projection of adjacent treads and at a right angle to the tread's leading edge. The greatest tread depth within any flight of stairs shall not exceed the smallest by more than 3/8 inch (9.5 mm). Consistently shaped winders at the walkline shall be allowed within the same flight of stairs as rectangular treads and do not have to be within 3/8 inch (9.5 mm) of the rectangular tread depth. "

Which leaves us with the all-important nosing (IF required, that remains the same at all flights between stories, if I understand this correctly);
"
R311.7.4.3 Profile. The radius of curvature at the nosing shall be no greater than 9/16 inch (14 mm). A nosing not less than 3/4 inch (19 mm) but not more than 11/4 inches (32 mm) shall be provided on stairways with solid risers. The greatest nosing projection shall not exceed the smallest nosing projection by more than 3/8 inch (9.5 mm) between two stories, including the nosing at the level of floors and landings. Beveling of nosings shall not exceed 1/2 inch (12.7 mm). Risers shall be vertical or sloped under the tread above from the underside of the nosing above at an angle not more than 30 degrees (0.51 rad) from the vertical. Open risers are permitted, provided that the opening between treads does not permit the passage of a 4-inch diameter (102 mm) sphere.

Exceptions: 1. A nosing is not required where the tread depth is a minimum of 11 inches (279 mm). 2. The opening between adjacent treads is not limited on stairs with a total rise of 30 inches (762 mm) or less." Underline is mine, from: http://publicecodes.cyberregs.com/ic...?bu2=undefined
Check locally with your AHJ.
Gary
P.S. Guide and definitions; flights-"Drawing 9", definitions- pp.18; http://www.abqstair.com/wp-content/u...copy_1__1_.pdf

Thanks Gary, I was hoping you would join in on this, I knew about the 3/8 inch difference but didn't know from a landing, I never had to deal with that. I have this saved and hopefully can remember where I put it.:)

Gary in WA 11-22-2012 06:11 PM

Always check Code interpretation locally, lol... others here may have better/different interpretation- or under the IBC. Just my 2 cents. The "other" Gary must be busy...

Gary


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