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-   -   Fastening stair stringers (http://www.diychatroom.com/f14/fastening-stair-stringers-24846/)

bacdef 08-06-2008 10:07 PM

Fastening stair stringers
 
Hello all !

I am building a set of stairs out of PT lumber for the garage stairwell.
I have all the math figured out, all three stringers have been cut and test-fitted, all steps are cut to length, in short I'm ready to assemble.

I have found abundant info on the planning and making of stringers and steps but very little is said about securing the project to the receiving wall(s) and/or floor.

The stairs are to be installed in a rectangular concrete stairwell.

The far short wall (while facing the way one would while going down the stairs) houses the basement door.
The right-hand wall and the wall opposite to the door ( the one that shall receive the stairs ) are finished with drywall over insulation.
The left-hand wall is bare concrete.

I need tips on how to attach the stringers SECURELY as this is the garage-to-the-basement heavy-duty path for heavy and cumbersome traffic.

Thank you for reading !

Termite 08-07-2008 07:53 AM

At the top of the stairs, I'd secure a ledger to the existing wall for the stair stringers to sit on or be hung to with joist hangers.

I'd also suggest using screws to secure the side stringers to the side walls. Concrete screws (tapcons or similar) on the concrete side, and wood screws on the framed side. Nails will often squeak at these locations so I'd opt for screws.

bacdef 08-07-2008 11:49 AM

Roger that kctermite

Ledger + joist hangers sounds like a good idea.

The finished "wall" is pretty much blue foam insulation bolted into the concrete with 1x3 furring strips and drywall on top so I wont trust it to hold much more than its own weight. I'm not trusting it to hold the stairs.

So right now I'm thinking I need to cut into the finished wall, install a ledger with expansion anchors and fasten the stringers to that using joist hangers of the appropriate size.

Joist hangers expect the joist to be level and my stringers are angled. Do I cut a notch in the stringers ? Full triangle shape like the runs and rises or just a saw trace ? Should I rather look for "adjustable" joist hangers ?

Since I will be removing the blue foam insulation to install a sturdy ledger is some sort of membrane or other protection between the ledger and the concrete in order ?

Again these stairs are to be installed in the garage so they are not outside per se but it will get rather cold and damp in the winter time.

Thanks for reading !

Termite 08-07-2008 12:57 PM

No membrane necessary at the ledger.

A small notch at the hanger seat is ok in my opinion. Keep the notch as minimal as possible. Or, you could use framing angles (sold in the same section as joist hangers...They're essentially a 90* angle for situations like this one) and 10dx1-1/2" joist hanger nails.

dhag 08-07-2008 01:41 PM

Joist hangers are the way to go, just notch enough to fit into the hanger. I did this for my basement stairs and they are STURDY!

bacdef 08-07-2008 02:54 PM

Quote:

Originally Posted by thekctermite (Post 146734)
Or, you could use framing angles (sold in the same section as joist hangers...They're essentially a 90* angle for situations like this one) and 10dx1-1/2" joist hanger nails.

Good idea there, I'm learning :).


Could I use scraps from the stringers themselves to form the proper angled padding ?

I'm curious as to what would be the more robust solution between notched stringers and un-notched stringers with added angles made from stringer scraps.

The arguments I can think up are :
#1 Any cut made to the stringers weakens them

#2 The added angle padding will be screwed in so part of the load will be beared by these screws (shear loading ).

Both situations seem undesirable and my instinct would have me lean towards the simpler solution of notching.

We're headed into nitpicking territory here, but this is good since it means I have all of the show stopping issues sorted.

BuiltByMAC 08-07-2008 09:31 PM

1 Attachment(s)
In addition to a positive connection at the top, think about this for the bottom of your staircase:

notch out 1 1/2" tall by 5 1/2" deep on the leading bottom edge of your stringers -
cut a 2x6 PT the width of your staircase (stringers only) -
attach the 2x6 to the concrete floor w/ concrete screws (Tapcons or similar) -
fit your notched stringers over that 2x6 screwed to the floor.
Now your stringers will have no possibility of sliding away from the wall.

Mac


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