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justadncr

stair width

justadncr
17 years ago

I have read the posts about stair rise and such but what I am wondering in width. My gc thinks stairs that are made from 2 x10s are to narrow and thinks they should be made with 2x12s. What do you all think. This is where you put your foot down.

Comments (14)

  • sombreuil_mongrel
    17 years ago

    Ready-made stair treads come in 11.25 and 9.25 inch widths. Both can be code-adherent and comfortable. It's actually a matter of how much room you have for the run of the stair, and especially how much headroom you have at the stair header. You don't want to build the stair with too long a run so that you bang your head on the way down.
    Casey

  • mag77
    17 years ago

    There are several ways to calculate stairs, but whatever formula used should vary the ratio between rise and run, so that the more the run, the less the rise, and vice versa.

    I use this formula: 1 run + 2 risers = 25. For example, if the tread [the run] is 9 inches, make the risers 8 inches tall. Big, grand buildings like museums often have treads as much as 14 inches wide, so their risers would be 5 1/2 inches. Most architects and carpenters aim for something around an 11 inch run and 7 inch rise as a reasonable standard for residential stairs. In practice, of course, it's seldom possible to follow formulas exactly, but there's plenty of flexibility in them.

    I hope I haven't bored you to death, but this is important in terms of safety and ease of use. Stairs built too far out of whack are dangerous.

    Getting back to your situation, I feel the difference between a 2x10 and a 2x12 is more than enough to call for an adjustment in the height of the risers.

  • dumaspup
    17 years ago

    I would have to vote with your gc IMO the 2x10 tread will be to narrow and feel uncomfortable

  • brickeyee
    17 years ago

    Check the building code for your area.
    There are not a lot of options on tread depth and riser height in most codes.

  • sharon_sd
    17 years ago

    It depends on the space you have available for the stairs. Assuming the rise vs run can be done correctly, 12 inch treads are usually more comfortable.

  • bus_driver
    17 years ago

    Heed what brickeyee has written. Building codes are becoming more restrictive on the permissible dimensions of rise and run. Our previous code permitted rise up to 8 1/8". New code has maximum of 7 3/4". That has resulted in significant, and not necessarily pleasant nor welcome, changes to some floor plans. The taller the ceiling, the greater the impact of this code change. Know the code before you do the faming.

  • manhattan42
    17 years ago

    As brickeye and Busdriver have stated, your local building code will determine the tread depth required for a stair.

    International Residential Code 2003/2006 requires a minimum tread depth of 10".

    You cannot meet this minimum tread depth with 2x10 sawn lumber which has a nominal depth of 9 1/4".

    2x12 sawn lumber treads would be minimum for use as a tread when using single boards for treads under IRC.

    Your GC is absolutely correct.

  • oruboris
    17 years ago

    Aren't most stairs done out of particle board type material these days? I was told its stronger and less likely to squeek, so I'm not clear why 2x lumber is relevent...

  • bus_driver
    17 years ago

    The possibility is that the original post is really speaking of the material for making the stringers. For stairs that have walls on each side, the stringers can be nailed to the studs and will be quite strong even if made from 2x10. For the center stringer(s), if used, I do not cut to full depth of the tread and riser, but leave one extra inch of uncut depth. If closed risers are used, the riser supports the front of the tread anyway. Use of construction adhesive for assembling ALL parts of the stairs will help reduce squeaks. Particle board is not stronger than any other stair material and typically will be the weakest of all the choices. Material choice does not cause squeaks, movement of one material against another causes squeaks.

  • brickeyee
    17 years ago

    " This is where you put your foot down."

    Does not sound like a stringer, sounds like a tread.

  • bus_driver
    17 years ago

    After reading it again, it certainly must be the tread. The phrase "put your foot down" is used in my area to descibe assertiveness.

  • sombreuil_mongrel
    17 years ago

    If this is a remodeling of an existing stair, using the same footprint, the old tread depth is "grandfathered in". I don't think the authorities can force you to change the run, which could force you to move the header also, so it meets the 79" (or whatever) rule.
    You should see the stairs we re-build (and recreate) in 200 yr old houses; they violate code in every dimension. I'm thinking of one 20" wide with 8 inch treads and 9 inch rise. oy.
    Casey

  • jdisciple23
    16 years ago

    I actually have a set of stairs that my ex-contractor built where the tread is definitely less than 9" in width. I also now know that this is a code violation, so I'm trying to figure out what my options are. Any suggestions besides tearing them out and building them all over again?