*
I’m building some long stringers(using all of 2″x12″x16′) and I’m having problems with the wood spliting. First, am I totally stupid for trying to make them so long? 15 steps rise=6.75″ run=10.5″
It’s the longest stringers I’ve ever cut. I’m using standard PT lumber, I can’t seem to find to many boards in good shape. Should I make shorter stringers and put in a mid-span deck/landing? I’ve got to go to a height of 8’9″.
I’m actually open to other materials and methods, I just need lots of room to go up the stairs.
Wellllll, am I out to lunch or what?
Cy ;->
Replies
*
Not sure what you mean by splitting. Probably need to pick better lumber. I always select the straightest, truest 2x12's I can find for stringers.
That being said, I think most codes require a landing to cut the number of risers to less than 13 at a time.
Also, outdoor decks are typically required to support a heavier load than an interior floor (60# per SF vs 40# per SF here), I'd guess that the same applies to the stairs.
Don't know what rise and tread combination you're trying to cut, but don't overcut, and add some additional posts as support under the stairs.
*I always scab a 2x4 or for something that long 2x6 PT along the iner side of the stringers. You might have to knotch the 2x6 depending on your cut. If you have a rise and run cut that has broke off glue it back on with some good ext. glue and screw it. I too would post it half way.
*I assume you're notching the stringers. If so, the uncut portion is probably no bigger than a 2x6. Would you span 16 ft. with a 2x6 joist? Why not leave the 2x12s whole and support the treads either with cleats screwed to the stringer or by routing mortises 1/2 in. or so into the stringer?
*16' is excessive even for a full 2x12 stringer. It would very bad for a notched or routed one. I would suggest using cleats or TA-9 or TA-10's with a double stringer, a 3x stringer if possible or even a 4x stringer. The concentrated impact loads on stairs are considerable, and any bounce is unacceptable.
*You got some good advice. Still, finding clear lumber that long is about impossible. Adding cleats to a solid board is a great idea. Why not just cut a bunch of 18" pieces of angle iron and bolt them in place with 5/16" galvy lags? I agree that stability is really important, and unnerving when it is absent. Definitely consider adding mid-point posts to cut down deflection (bounce) and also definitely consider adequate cross bracing let-in to the underside of the stringers to eliminate racking (sideways wiggle). Also, I always use bolts for all important structural connections in the outdoors. This would include: stringers, posts, braces, newel posts, etc...By the way, the Mass. State Bldg. Code says that a landing is required at every 12 feet of vertical rise. That would make it occur at every 13 risers as someone stated cause the riser can't ever be greater than 11 inches anyhow.gg
*With midspan posts your troubles will go away... I agree with Mike 100%. You are trying to do too much with too little. Any chance of attaching one side to the building, saving a post?
*Check again. I don't know of any code that permits greater than 9" rise. 8.5" is the common max. for residential. I think you have an 11" run confused with rise.
*Cy,7 and 10 is the norm for stairs. PT wood in that length is hard to find straight. Someone posted awhile back about using glue lams for stringers and I like that. They won't split at the grain because there is no real grain. However, I'm not sure they would work in an exterior situation.You have a lot of good advice here. I like the "don't cut the notch" advice. Leave the stringers intact and put the treads inset. There is a Simpson product for this, I believe. For exterior treads, you don't need risers.If you must notch out the stringers, you will need three horses (stringers). That is too much span for not having something in the middle underneath them.You didn't need my advice, I'm not saying anything that hasn't been posted already, But I would like to agree with what has been said here.Ed. Williams
*Jay:Decks are required to support 40 psf here, in NC, and the support requirements for outdoor stairs are vague in our code book, so inspectors don't demand much in this area - it is common here for deck stairs to be built with out footers! In addition, it's not uncommon to see 2x10s rather than 2x12s to be used as stringers. Further, our code does not have any requirement for requiring "a landing to cut the number of risers to less than 13 at a time"Could this be a snow load thing?Cy:Find some green board that is wet and heavy. It splits less during construction than dry lumber. Be sure it's SYP (southern yellow pine) if available in your area. The other advice about 2x4 or 2x6 scabs, mid span support, etc that was given here is right on... When in doubt - make it stout!
*
I am out to lunch!
WOW!!!!
Thank yall!
I do admit stairs are new to me and frankly all of the engineering books don't really go into the details discussed here.
I did think that notching the stringers that long was really weaking the boards. Boy it did. Live and learn.
Thanks! I'll let yall know the final results.
Cy ;->
*
I'm building some long stringers(using all of 2"x12"x16') and I'm having problems with the wood spliting. First, am I totally stupid for trying to make them so long? 15 steps rise=6.75" run=10.5"
It's the longest stringers I've ever cut. I'm using standard PT lumber, I can't seem to find to many boards in good shape. Should I make shorter stringers and put in a mid-span deck/landing? I've got to go to a height of 8'9".
I'm actually open to other materials and methods, I just need lots of room to go up the stairs.
Wellllll, am I out to lunch or what?
Cy ;->
*
Cy,
Please check your math. You said your total height was 8ft-9inches, right? Convert that into inches, and that equals 105 inches. Divide that number by 7 and you have 15 rises and 14 treads. A 7 inch rise is the "perfect" rise. This would allow you to also increase your tread size from 10.5 to 11 (or use a standard 2x plank as is at 11-1/4 inches.) Your overall run (total stair length) would be the same at 157.5 inches. Why are you going 6-3/4 rise and 10-1/2 tread? Both will give you the same, but 7 is normally the rise to strive for and this will save you lumber by using one less tread.
If it was me, I would use 3 stringers made from 2x12s; the middle one being a notched out job and the other 2 side stringers being full size with 2x4 cleats bolted to them with galvanized carriage bolts, not lags. The middle cut-out stringer can be reinforced with a matching cut-out stringer made from treated 1/2 inch plywood, and this plywood would be clenched nailed to the 2x stringer. I would definately put in a landing about halfway up the staircase, and make this landing the same width as your stair tread length. And, don't forget handrails. Good luck
Davo