Attaching wooden staircase to concrete walls and slab

[Wayne Whitney]

Hello,

I need to build a rough half-staircase to exit from my basement to grade. It will be in a corner of the basement, so one side will be up against a concrete retaining wall. I understand how to build the stringers and that anything with a face in contact with the concrete should be rot resistant. But I'm wondering how to make the various attachments:

Side wall stringer: directly to the concrete retaining wall? 3 3/4" tapcons OK? How many?

At the top of the stringers: a ledger board on the concrete wall? Joist hangers to attach each stringer to the ledge board?

Bottom of the stringers: directly to the concrete slab, or to a furring strip on the floor? If directly, does this mean each stringer needs to be rot resistant? How does one fasten the stringer here, in either case? Toenailing into the furring strip?

Thanks, Wayne

P.S. I imagine wanting to finish the stairway in the future if I every finish the basement. Anything I need to plan now?

[RicodJour]

stringer

The stair does not need to bolted to the side wall. Stairs are self-supporting, and are structurally equivalent to an inclined beam. As long as you have adequate connections at top and bottom, it's not going anywhere.

A ledger board at top is pretty standard. Joist hangers to the ledger board is another possibility but affect the finished look. Another way is to bolt 3/4" plywood to the vetical faces of the stringers and use that to hang the top of the stair.

The bottom of the stair stringers are usually notched to fit around a perpendicular 2x4 cleat bolted to the concrete floor.

Here's a link that may be helpful:

shows LVL stringers, but is applicable in your situation.

You are correct that you want to keep the end of the stringers from sitting on the concrete floor. They will tend to wick up any moisture in the slab. If your basement is dry, and you don't anticipate any problems, you can epoxy coat the cut ends of the stringers where they touch the concrete. That's simple and a 95% solution at least.

R

[m Ransley]

Into the concrete, Lag bolts and lead anchors have alot more strength. Exterior stairs are better treated especialy in shade

[ameijers]

I'd build the thing pretty much as a stand-alone self-supporting unit (think mobile home steps), and maybe anchor to the wall with a couple of lag bolts set in anchors. Hell, even a stack of appropriately sized 2x8 and 1/2" plywood boxes, construction adhesived and toenailed together, would work. Yes, any wood touching slab needs to be rot-resistant, and if these steps face an outside weather door, you probably want the whole thing to be treated wood. Deck department at big box may have a precut stair kit, if your door is at a common deck height above interior slab. At the price of good wood these days, especially if this thing is 'temporary', I'd also check with the local mobile home and fire escape dealers and precast concrete stores, and see if they have a scratch'n'dent or used prebuilt item that would fit your needs, assuming you have a way to get it into the basement. Don't forget that if there is a door at the top, especially one that opens in, you want a landing. Inspectors frown on doors that open into space, these days- dunno why.

aem sends...

[Wayne Whitney]

OK, I like the idea of a ledger board. What's the best way to attach the stringers to it, joist hangers, angle brackets, or toe nail? And to attach the ledger board to the wall? This link says wedge anchors:

This obviously puts the bottom of the stringer against the concrete. What about using a sleeper with the bottom of the stringer resting on top of it the full width? Then again joist hangers, angle brackets or toe nails. Wedge anchors to hold down the sleeper?

Thanks again, Wayne

[Robert Allison]

You could do that, or you could set the stringers on a waterproof membrane such as that used under sole plates.

The wedge anchors or expansion anchors are all good to hold down your sleeper. If you screw the sleeper to the bottom of the stringers, then set the stair stringers in place, there is no need for angle or joist hangers. You want to set the stair stringers first, then bolt down the sleeper.