Basement Stairwell Framing

First Floor Subfloor

The subfloor is nearly done. I just have to put down a thin, 4″ strip along the North wall. However, before I can finish that up I needed to fix the stair opening to the basement along the outside wall. When Matt B and I framed it last year, we cut back the joist ends along the outside wall. Now, as with all of the other joists, they need to be at the right level. I took a look at it and decided it would be easier to pull out the joist ends and redo them.

Stair opening
Stair opening (also pictured: giant rack of old floor boards in basement)

I first tried cutting the joist ends down to the right size, but they were not in great shape, and a couple of them broke in half. I tried cutting some new pieces but nominal 2x10s are too loose in the rough sawn notches and I couldn’t position them as accurately as I wanted. In addition, I decided I wanted some sort of bracing down the length. A full 2×10 would close up the cavity and prevent it from being spray-foamed. Notching a 2×4 into the ends would work, but would be a real pain.

Instead I decided to just put new 2x4s (planed a few times) on top of the rim on the other side of the wall studs, screw a 2×4 onto the face, and then for good measure, shore it up with some support blocking glued and screwed underneath.

New framing, start of subfloor
New framing, start of subfloor

With the new structure built, I started working on covering it in subfloor. I wanted the OSB to span the opening, which required some fancy carpentry. The narrow section along the wall needed a groove because the rest of the subfloor is tongue and groove. I’ve been cutting my own grooves out of my leftovers on the table saw instead of wasting full panels. The problem here is that the piece is shaped like an ‘L’, so cutting the groove on the inside edge was complicated by the fact that I couldn’t slide it all the way across the table saw.

I started by cutting the groove as far as I could on the table saw, which left about a foot or so. Then I used my circular saw to get closer, leaving about 4″. Finally I used my oscillating tool to cut the sides of the groove and a wood chisel to finish it up. The piece slid in and fit like a glove, tying this section in with the rest of the subfloor. Once I finish this edge, I just need to plane and glue some seams and this project will finally be done!

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