Hi,
I need to add a third stringer to a stair that I built with just two. I thought it would be adequate since I’m using 2x treads, but the inspector says no.
Does anyone have any tips or tricks for scribing the new stringer from the existing, which are firmly nailed in place at the walls? I did space them out on 2x4s for the wallboard, so they’re 1.5″ from the framing.
Thanks
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Replies
Did you save your pattern?
Run a solid piece (2x6 or 2x8) under the middle, touching the back edge of each tread. Then cut wedge-shaped pieces to fit between tread and the new member. These can be sized by placing a rectangular piece up against the tread and then scribing against the diagonal. Hold the wedges in place with nailing plates or scabs of plywood.
I should have said that the treads and risers are not in place yet, so I've got open access.
There are four runs of 7 risers. I did not make a pattern. I used a framing square with stair gauges to make the first stringer for each run, then scribed the second one from that -- should have scribed two!
I'm thinking I'll make a mock-up of the top and bottom steps, and screw a stretcher between them while I hold them in place. This will make a pattern for the top and bottom bearing surfaces. Then I'll cut those surfaces on the new stringer, put it in place, slide it against an existing stringer, and somehow reach in between the framing and the new stringer to scribe it, probably with a pencil stub shoved into a hole in a short board.
Anyone know of a better right-angle marking device?
Are there risers? Are the two stringers supported by walls?Andy
"Never try to teach a pig to sing. It wastes your time and annoys the pig." Robert A. Heinlein (or maybe Mark Twain)
"Get off your dead #### and on your dying feet." Mom
"Everything not forbidden is compulsory." T.H. White, The Book of Merlin
Yes and Yes. Didn't seem to matter to Mr. Inspector.
My policy is to do what they ask -- seems to make everything go much smoother. In this case, it's a pain, but not really expensive or difficult.
Oh, I love arguing with them, politely. Somebody has to keep them from inventing requirements. On that one, assuming he's going by the IRC, he's just plain wrong. Code doesn't even say specifically what the design load is for stairs, although it's assumed to be a 40 lb live load and a 10 lb dead load. There is no prespription for how to achieve that. Some counties in VA do publish prescriptive requirements - Fairfax, I think.
If you're interested in the topic, go to the USDA Forest Products lab and search on stair loading. There's a great article there. Andy
"Never try to teach a pig to sing. It wastes your time and annoys the pig." Robert A. Heinlein (or maybe Mark Twain)
"Get off your dead #### and on your dying feet." Mom
"Everything not forbidden is compulsory." T.H. White, The Book of Merlin
I knew exactly what you were thinking. Inspectors, and really much of the construction world, just don't understand how good riser design effects the strength of stairs.
I've noticed a troubling trend from our architects. It seems that so many builders are screwing up stairs that very specific specs are being dictated on designs. These stairs are designed to be idiot proof, not the best solution and definitely not sleek. You would have laughed your asss off at the huge/awkward simpson hangers I was handed.
Beer was created so carpenters wouldn't rule the world.
Here in the east, a lot of stairs are made with housed 5/4 x 10 stringers. Two of them. Part of the strength comes from the uni-body construction, but really, it's all in the risers. They work exactly like the 1/2 in. OSB webs in an I-Joist, except they're 1/4 in. thicker. If you can span 12 ft. or so with an 8 in. I-joist, there's no reason on God's green earth you can't span 12 ft. with 1x8 risers. If you're using risers, a center stringer is almost never needed, assuming the two outer stringers can bear the overall load.
And speaking of stringers, that same inspector who is insisting on three of them is probably OK with them being made from 2 x 12. Once you notch the edge of a piece of structurally graded lumber, it loses its grading and is no longer acceptable for structural use. You might think that a notched stringer has the capacity of say, a 2 x 6. Not so. Ripping a 2 x 12 in half does not two structural 2x6s make. Lumber is cut and graded to place the best material on the edges, where tension and compression play out. The stuff in the middle can be crap, as long as the edges are good. Rip or notch a plank, and you're changing its ability to carry loads in ways that aren't obvious.
Back in the day of old growth lumber, that wasn't such a big deal as the lumber was more uniform. It's very important today. I advocate LVL or at least OSB rimboard for stringers, as it maintains the structural integrity expected of its remaining dimension when notched.
Done ranting.
BTW, I respect inspectors who know their jobs better than I do. Those that don't need to find a different line of work.Andy
"Never try to teach a pig to sing. It wastes your time and annoys the pig." Robert A. Heinlein (or maybe Mark Twain)
"Get off your dead #### and on your dying feet." Mom
"Everything not forbidden is compulsory." T.H. White, The Book of Merlin
Love your tagline, btw. We should share one of those potential limiters sometime.Andy
"Never try to teach a pig to sing. It wastes your time and annoys the pig." Robert A. Heinlein (or maybe Mark Twain)
"Get off your dead #### and on your dying feet." Mom
"Everything not forbidden is compulsory." T.H. White, The Book of Merlin
Andy,
You've made me think here. There were no stringers in place at the inspection - just rough temp treads. I'll call Mr. Inspector about this -- maybe the fact of risers will save me the extra stringer.
I used LVL for the two stringers, understanding exactly what you said about 2x12s.
I love YOUR tag line, by the way! (I love Heinlein.)
Scott
Heinlein is a classic.
BTW, to get the most from the risers, they have to be screwed and glued to the treads top and bottom.Andy
"Never try to teach a pig to sing. It wastes your time and annoys the pig." Robert A. Heinlein (or maybe Mark Twain)
"Get off your dead #### and on your dying feet." Mom
"Everything not forbidden is compulsory." T.H. White, The Book of Merlin
Of course.
If you built your stairs well, just use your rise and run calcs, and make another stringer.
BTW, how wide are your stairs?
Edited 11/28/2006 3:56 pm ET by MSA1
The stairs are 38 to 42 inches (one of the four runs is wider because of the wall framing.)
Yes, that method should also work -- I did careful layout and cutting.
If their aren't any treads or risers on them cut the pattern stringer out and use it to make another stringer.
Or cut your level cut on the bottom, measure up to the plumb cut on the top and cut it.
Then you now have a stringer blank. Tack it against your pattern stringer and then mark it out.
As your first two stringers are up, you will not likely find it easy to 'slip' the middle stringer in position. And it will not likely 'rotate' into position either. Let us know how it goes.
There are no treads or risers so it should drop in straight down from above.i"ll keep you posted.
Could you just temporarily screw the new board you're making the third stringer out of under one of the existing stringers and transfer your vertical cuts down to it using a square? Then just measure the dept of each proposed cut and use a level ( or square again, I guess) to get the horizontal cuts. Unfasten the new board and cut. If this is stupid, I'll fall back on that I'm up with a migraine and can't sleep despite just having taken more pills!
Edit: You could also just temporarily screw the new board right over the stringer and mark your cuts where they hit the top edge, unscrew it and use a square to transfer lines, then cut. Those littl thingys that attach to your square would help.
Edited 11/29/2006 1:26 am ET by Danno
I think you should try the "Sir Christopher Wren" approach.
When building St. Paul's cathedral in London after the old one burned in 1666, the review board told him his design needed more columns for strength.
He put them in, and it was not until renovations in the 19th century that anyone realized he had left all the "additional" columns 1" short!
Nice "gotcha" from the grave.
Forrest
thats a good one....
maybe that's why they need the reno though? maybe could have held off another 100 years.
<maybe that's why they need the reno though?>
Yeah, nobody seems to care about quality anymore . . .
;-)
Forrest
you didn't say that there were no treads or risers.... you said "built" not "am building"
just cut the top and bottoms - slide it in place , scribe it and get on with it dude :)
amount of stairs I see built into homes with only 2 stringers is ridiculous.( 3 is not always required) as far as I'm concerned - middle stringer or don't bother.
PS...you mentioned because you were using "2x" for treads. no offense but 2x is a terrible choice for treads. only a matter of time before they warp and cup - trust me.
if you have the middle stringer at least you have something extra to screw to help fight the eventual cupping. another thing you can do is run some shallow kerfs(about 3/8" to 1/2") couple inches in from the each edge. that will aslo help combat cupping.
I saw Jed Dixon at the JLC show in Seattle earlier this month ( Stair builder) he uses 3/4 " ply w 3 stringers . ( his mock up had 2 ) Personally I will use nothing but 1" plywood, for any stair I build. when you walk on a set of stars they should feel solid. plywood will never shrink and cup like dimesional lumber does. so at the very least go with 3/4 ply next time.
Edited 11/29/2006 6:33 am ET by alrightythen
OK, should have said "roughed in."
I'm interested in the cupping concern. It's a rustic ski house, so I wanted the robust plank look and feel. Each tread is going to be glued up from 2 pieces 1 1/2 x 5 1/2. I'm using reclaimed 100 year old fir. The boards are re-milled from very straight 12' 4x6s that were salvaged from an old barn and then sat in my lumber shed for 12 years.
I expect that gluing these up rather than using single 2x12s will help prevent the cupping.
What causes this cupping, in your view? Is it moisture difference between the space inside the stair below the treads, and the rest of the house? This stair will be closed, but with T&G below, not drywall, so it should breath pretty well.
if the wood is that old..I wouldn't be concerned then.
yes it is mositure - in the treads themselves, when stairs are framed with new framing limber.once the wood is seasoned one should be fine....
100 years...I'd say is a pretty good seasoning...go for it.
what Andy says is essentailly true. for solid stairs, I still will always use a middle stringer in. IMO stairs are one of the few things that you can not over build.
Edited 11/29/2006 10:34 am ET by alrightythen
Jeeze, by the time I got done reading all the posts I could have relayed out and cut and installed the darn stringer and the treads!