Deck stair stringers, landing, and footers help please
WorkerBee630
| Posted in Construction Techniques on
I am building new stairs for my deck that will be 84″ wide. The treads will be 16″ deep. We are using the Simpson strong tie tread brackets for the outermost stringers, but will need to obviously use cut stringers for the remaining support stringers in between.
First question: Will a 2×20 be significant enough for a 16″ tread cut?
Second question: for an 84″ wide landing, can I get away with the free floating slab and have my handrail posts attached via standoff brackets, or do I need footers to the frostline and THEN the slab over that? And if I need to use these sonotube footers under the slab, how many for an 84″ width?
Replies
Why are your treads at 16”? The only time you really see treads that deep are on commercial projects when you have only a few risers. The only time I use a tread that deep in residential is when there is only one step up to the deck as it creates a more comfortable step. Having multiple 16” is going to make the walk up and down stairs feel really weird. The ideal ratio for steps is 7” riser with 11” tread. General rule is you try to get as close to this ratio as possible.
My wife likes the oversized stairs for the simple fact it's our only entry into the house, and when I got hurt and had to use a Walker, those 11" treads weren't easily accessible. Friends of ours had these size stairs leading down from their driveway. 16"/4" and I had no trouble there, nor did anyone else walking normally have an awkward time at those measurements. There will be 5 stairs.
I’m assuming you and/or your wife have limited mobility issues? May want to consider a ramp vs stairs if you are using a walker, much safer and easier to manage.
If you are keen on stairs. The 2x20 will be fine for stringers. I would pour frostline footers for all the stringers, but a floating slab will be fine for the landing if stairs are not resting on it. If you are concerned about frost lifting slab pour frostline for that. It’s a little overkill in my opinion. I doubt the slab will move that much, unless your grading creates a water trap for ice buildup at landing.
We actually have large natural rock laid out like a puzzle in cement now that is our landing, and our stairs end just shy of that. I'd honestly rather keep that and just do the footers for the stringers. I will have to chisel up some of them to move them back to make room for the new stringer footers, but other than that. We don't have mobility issues yet, I just had an accident and the walking boot paired with the weakness from the healing fractured femur made a cane too wobbly, so the Walker was handy. But, seeing as though we are aging, why not make it a little easier now while we can. If God forbid one day I need a ramp, I'll pay someone else to out that in! But the stairs, I enjoy being able to do this for her.
Agreed. Good luck!
Thanks, but I am finding I'm running into some trouble. No lumber suppliers near me have or can acquire 20" wide lumber. Without them I can't make the center stringers. Nor can I even make the outermost stringers. I've looked at possibly doing box stairs instead but it's such added labor! I am at a loss for ideas now.
There was a tip in fine home building a while back about stacking lumber horizontal. A 2x10 and a 2x8 ripped down to 6 and 3\4 should work.
I was wondering where you were going to find 2x20. You can use steel for stringers with angles welded on for tread attachment. A steel fabricator can help with this. Or you can build steps as individual boxes. Or build walls on side of steps to act as support for treads and risers. Lots of options, but all depends on the look you are going for.
Well I've been looking for that article on stacking, but since the outside stringers aren't going to be notched I was hoping for some sort of fix. I think what I'm most worried about is, if I do the built up box style or walls, etc, is that a giant slab of 36" deep frostline cement pad for all that to lay on? There's no real footers when I'm covering that much ground.
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Check out this link. http://www.builderbill-diy-help.com/stair-tread-material.html
The first pic of stairs may work well for you. I have a pic of a set I did years ago, but I can’t download for some reason.
That rise/run wouldn't meet code in my area, but assuming its OK where you're located, I think 2x12 should suffice for your stringers as a 4" rise and 16" run is a very shallow notch.
The app BuildCalc has a great stair function that renders a drawing and specifies material width and length. It's not necessary to buy it just for that reason, but having a construction calculator can be handy for many tasks.
And a low-tech way would be to use a framing square on a sheet of plywood or posterboard, set the square on 4" and 16" (or whatever your rise and run are) and draw the step. Then register the short edge of the square on the edge of the plywood or paper, and with the long edge of the framing square aligned with the vertex you just drew, scribe a line outside of the area that would be notched for the step (perpendicular to face of plywood). In my area, you need a minimum of 3-1/2" of "effective depth" or "throat" -- the wood left intact after notching at this thinnest point, when measured perpendicular to the edge of the bottom of the stringer. So I would measure over 3-1/2", make a mark, and measure from the face of the plywood to this point, then round up to the next available material width.
Framing square usage can be hard to describe, but it should be quick and easy -- just be sure you look up the effective depth requirement for your area.
You don't need 2" X 20" lumber at all. Large treads like that are never built with conventional stringers. Typically you would use a 2" X 8" and add the rough tread framing off of that.
Her's one very simple way to accomplish your tread depth.
https://www.youtube.com/watch?v=DAjEzZ6nO6U