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cutting stair stringers

22K views 61 replies 11 participants last post by  CVGFir 
#1 ·
Im trying to lay out some stair stringers and im pulling my hair out. The problem is that the stringers are right at the length where 20' will work, but i don't have room for waste


At first i was laying the stringers out so they would be flush with the existing 2x12 and then put plywood roofing an 3" of decking on, so its all flush on the first step. The problem is with cutting 3 1/2 off the top step, it barely leaves anything to attach to the 2 x 12. Now im thinking i should make the first step lower, so you step off the deck down onto the first step.
Can anyone help me lay this out?

The concrete pad is 170" to the edge of it, so i figure to the front of the step it should give be 185". It will be 129 1/4 to the top of the decking, although at the moment, just the roofing is on
 

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#5 ·
then my stairs would be in the dirt with the front of the first step touching the concrete.



I got it figured out though. Subtracted 8 1/2 (7 inch step plus 1 1/2 tread) from my original 129 1/4 calculation, to give me 120.75. divide that by 17 and i ended up with roughly 7 3/32. To give me the distance needed to get on to the concrete i went with 11 1/2 runs. This made the back of my stringers clear the concrete by 8 inches or so. Stuck them in place, and they look perfect. Glad it worked out, cuz i was sure pulling my hair out earlier. The real problem i was having was that i kept thinking my 20' 2x12's were too short
 
#6 ·
that must some wacky american code, in canada its no more than 1/8 variance between risers.. if you have to make it up you add or subtract 1/16 over 6 rises, cant do it all at once

also with a total rise of 129", you have to have a landing.. code requires a resting point as soon as a flight of stairs has 13 or more risers
 
#10 ·
There are a number of problems here-

The pad was poured before the stair was drawn out and so isn't in the right place.

A 20' stringer is too long for a single flight of stair, it will be bouncy and perhaps over stressed.

The sub-tread, roofing and 3 1/2" tread material? What's going on?

There should be a landing on this stair.

That'll do for now, do you have a jack hammer?
 
#12 ·
I'm not worried about supporting mid span, that's not. Problem. But having a landing required would suck. The concrete is plenty big enough so I have room to extend farther. It just couldn't be too short. The roofing is because this is a combination carport and deck. It has torch down roofing and then I'm putting 2x4 sleeepers down and then screwing the deck to the sleepers, to not puncture the roofing.


The only reason I'm building a deck/stairs is the building inspector said I need permanent stairs up to my storage trusses. He said I have too much headroom up there and it therefore requires permanent stairs. The original pull down stairs don't count.
 
#15 ·
any person walking up or down a flight of stairs will develop a memory in regards to how much to raise their foot to walk up the stair comfortably,, any more than 3/16" becomes very awkward and makes it more likely for the person to trip.. hence our code of max riser variance of 1/8"

what are you framing your stairs with to have more than 13 rises in a straight flight of stairs and not have issues with the stair sagging our bouncing? 2 ply lvl's

we have much stricter codes in a number of areas for different trades


one of the scariest ive heard is regarding your electrical,, cant remember teh exact distance but you can have as many outlets as you can fit within so many feet. here you cant have more that 12 outlets or light boxes per circuit. with out code electrical fires are far less likely to happen as
 
#16 · (Edited)
I think here your allowed 1/4 or more varience. But it doesn't matter, my stairs turned out perfect. Within 1/16. This had 10' of rise because its 8' of headroom, plus a 2x12 plus 18" grade change.

I'll just have to call the ahj tomorrow to find out about a landing. Hopefully it really is 12' rise. Which I'm only at 10'9. Landing would be stupid in this situation. This is just access to storage over my garage. If the stairs have significant bounce I will just put posts under the midpoint. The stringers are 2x12 reinforced with 2x4
 
#19 ·
Found my answer on the landing. 12' is correct. So I'm in the clear on that


R311.5.4 Landings for stairways. There shall be a floor or landing at the top and bottom of each stairway. Exception: A floor or landing is not required at the top of an interior flight of stairs, provided a door does not swing over the stairs. A flight of stairs shall not have a vertical rise greater than 12 feet (3658 mm) between floor levels or landings. The width of each landing shall not be less than the stair-way served. Every landing shall have a minimumdimension of 36 inches (914 mm) measured in the direction of travel.


To take care of bounce, I'm going to reinforce them with 2x6. If it still has bounce, i will put 2 vertical posts with a horizontal at mid point
 
#22 · (Edited)
This one should get you just what you are looking for. And, using 17 treads, it keeps you within code, except for the fact that you can only go 84" on a span with cut stringers like this, not 170+. You'd be within code, I believe, if you used solid stringers.
This drawing assumes 1-1/2" thick treads. And it puts one tread at the top deck height.
 

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#23 · (Edited)
While I'm thinking about it...............

Since there always seems to be a lot of concern about not leaving enough "meat" in the stringers after cutting out for the risers and treads..... I do hope everyone knows THIS trick....

All you do is shift your cut layout 1" out into the space alongside the 2x12.

This gives you one more (additional) inch of supporting run in the stringer without sacrificing anything.

It is not necessary, at all, to have those "points" on your stair stringers. In fact I know that some of you who have cut many stringers have knocked off a corner every now and then. What did you do? You probably picked it up and tried to glue or tack it back into place...... Right? Do you honestly think that did a bit of good? C'mon, think about it. The points do nothing. You never even nail out there, and the riser boards support the treads anyway..... NOT that flimsy, fragile point of wood.

This drawing shows stringers made for identical rise and run.... one cut with points (thus leaving you with only 5-1/8") and one with a shifted layout (leaving you with 6-1/8")

You sometimes have to learn to think outside the box. But keep in mind that stringers of this type and length would be illegal on a deck.
 

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#24 · (Edited)
While I'm thinking about it...............

Since there always seems to be a lot of concern about not leaving enough "meat" in the stringers after cutting out for the risers and treads..... I do hope everyone knows THIS trick....

All you do is shift your cut layout 1" out into the space alongside the 2x12.

This gives you one more (additional) inch of supporting run in the stringer without sacraficing anything.

It is not necessary, at all, to have those "points" on your stair stringers.

This drawing shows stringers made for identical rise and run.... one cut with points (thus leaving you with only 5-1/8") and one with a shifted layout (leaving you with
You sometimes have to learn to think outside the box.
Unless you're not using risers. And, before you have a pattern, you really need a framing square, which will be tricky for the layman (not you or I) to figure w/o that leading point to measure from.
 
#27 ·
referring to how much meat is left in the stringer after the notches are made is called "effective depth",, a 2x10 stringers is the minimum allowed here, it just works out to have 3 -1/2" of depth left in the stock. i use 2x10 for stairs with up to 7 rises, then i either up it to 2x12 or even 11- 1/4 lvl's for long flights of stairs.. you want a stair with nearly no bounce at all use lvl.. heavy as hell though..
 
#29 ·
The stairs don't seem to have too bad of a bounce. Enough that it would be annoying in a house but mine will rarely be used. Have to actually jump to get movement. The real problem seems to be racking back and forth. Maybe it would go away when the stairs are complete but just with treads on, it moves pretty easy. Im going to sink some 4x4 posts into the ground to double as reinforcment and part of the railing system.
 
#33 ·
If it doesn't, just add an "X" brace to the two 4x4's. (Keep the bottoms of the "X" high enough that you can run a lawnmower past them.)
 
#36 ·
This should clear things up a little; pp.17-need risers, fig. 27 max. stringer span 7'; 5"min, throat, 16'6" max. closed stringer span; pp.2- table 1; fig.31- top stringer hanger required; fig.34- post footing depth to reduce stringer span; ect. etc.
http://www.awc.org/Publications/DCA/DCA6/DCA6-09.pdf

And, always check locally for amendments to codes.

Gary
 
#37 ·
This should clear things up a little; pp.17-need risers, fig. 27 max. stringer span 7'; 5"min, throat, 16'6" max. closed stringer span; pp.2- table 1; fig.31- top stringer hanger required; fig.34- post footing depth to reduce stringer span; ect. etc.
http://www.awc.org/Publications/DCA/DCA6/DCA6-09.pdf

And, always check locally for amendments to codes.

Gary
Thanks, Gary. I'm embarrassed to say I missed this. It is, after all, a deck. :oops:
 
#45 · (Edited)
Level

You might have to shift the landing to the next higher step than I've shown, or make the landing longer. Eight treads on the bottom and eight treads on the top would work out just about right. (I was just too lazy to redo this drawing after I saw that I miscounted.)

Don't forget you can make a 90 degree turn in the stairs at the landing to use up less yard space. Or even a 180 degree switch back if you want.
 

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#47 ·
Out of pure coincedence my supports are 7' on center. 9' measured diagonally along the stringer but 7' going level. Things are working out. And the stairs stiffened right up with the posts
Check to be sure that's legal without a landing. (If I'm reading you right.)
 
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