Basement Stair Opening

We’re probably not going to have a finished basement for a long time. When we do finish the basement we’re going to lower the basement floor in order to gain some additional headroom. That will be after we finish the first floor, the second floor, and the outside. In short, we probably won’t have stairs going down into the basement for years. However, we do need to frame out the opening for the eventual stairs in order to finish the first floor. This is just one small piece of the massive 3D jigsaw puzzle we’re working on. Framing the opening for the stairs comes before we put down new subfloor comes before we build a stair landing comes before we build new stairs to the second floor.

Original opening

My friend Matt B offered to spend a couple days of his week off down from Milwaukee to work on our house, so I wanted to tackle a two-person project and with the beam mostly done it seemed as good a time as any to start framing the first floor. I finished the stair planning so I knew where we were putting things and I picked up the necessary lumber and some joist hangers. The floor is framed with 2x10s that span the width of the house. Four had been cut at some point to make an access door down to the basement that had then been covered over with hardwood floor. The hole wasn’t properly reinforced and the joists were patched with 2x4s to provide a nailing edge for drywall in the basement.

Floorboards removed

We removed the 2x4s and cut back the floorboards where we’d be working. Since the new stairs are further back in the house, the cut joists only partially coincided with the joists that needed to be cut for the new opening. To conserve lumber we did a swap, cutting the joists back to the beam and replacing the cut joists with full pieces and vice-versa. We used mending straps to join together the cut joists at the beam.

Mending straps

At the ends of the opening we doubled up the joists, gluing together the 2x10s and putting in two rows of screws every 12″. We had to remove the top courses of brick to expose the 6×8 wood sill on top of the foundation. The joists were notched into the sill, so we had to enlarge the notches to fit the doubled joists. Once the ends were in place we attached joist hangers and dropped in the doubled up joist along the length of the opening. This was glued and screwed the same way as the ends.

Notched rim board

At this point we ran into trouble with the joist hangers. The existing 2×10 floor joists are rough-sawn, meaning they are much thicker than the “nominal” 2x10s they make today. Joist hangers are designed to accommodate the 1½” modern 2x10s. It turns out they make joist hangers for rough-sawn 2x10s, but I didn’t know that when I first exchanged the hangers for LVL hangers only to discover they were now too tall, then exchanged them back for the original hangers and bent them into shape with a hammer. Oh well, they’re installed and not going anywhere. The new structure is very solid, though I still need to repair the brick between the joists.

Hangers installed

In order to get everything straight I used a jack post in the basement to push the joists into position before installing the hangers. I’ll still have a lot of shimming to get the subfloor level thanks to the wonky nature of the joists, but everything here is straight. Thanks to Matt B for all his assistance!