Framing Basement Walls: Stud Length, Plates and Anchoring

Framing a basement wall starts with measuring, and one rule from this basement project is simple: take the shortest wall height and subtract 3 in. to get the stud length. For a 90 in. gap between the floor slab and the joists above, studs are cut to 87 in. to allow for the plates.

Plates, studs and spacing

A basement wall has a top plate, a bottom plate and studs placed 16 in. on center. The bottom plate touches the concrete slab, so it must be pressure treated; the top plate can be standard kiln-dried lumber. Rigid foam insulation was installed in the previous episode, since that is typically done before framing.

Measuring and building

The wall height is the distance between the slab and the joists above. Measuring in a few locations and using the shortest value lets the wall be lifted into place, though shimming may be needed before the top plate is anchored to the joists.

The creator recommends marking 16 in. on center along the top and bottom plates, crowning every stud so each board faces crown up, and using 3 1/2 in. nails with a framing nailer. He uses two nails per connection.

Anchoring

The wall location is marked on the slab with a chalk line. Once the wall is in place, a carbide-tipped bit drills through the bottom plate into the concrete and Tapcon screws secure it. A level checks that the wall is plumb before it is anchored to the joists above. A powder-actuated tool, which uses gunpowder to drive a nail through the plate into the slab, is mentioned as a faster option he did not have.

Stick framing and its cost in time

He chose stick framing: lifting the plates and cutting each stud individually afterward, toe nailing them with two nails per connection. He calls it inefficient and says that if he did it again he would frame the entire wall on the floor, mark the plate spacing beforehand, and probably use 16 ft plates. Because the walls carry no load, the window framing only needs to support drywall and omits jack studs.

Where a bump-out occurred, he fastened a furring strip with Tapcon screws and set the wall flush with it so the drywall would line up. A small closet around the sump pump was framed as three smaller walls, with the door framing to be added later.

Corners and doors

Inside corners use California corners: a typical corner stud plus a second stud turned sideways on the inside face of the first. This allows better insulation and gives backing for drywall. The bottom plate must be cut out wherever a door will go.