Advice on leveling / sistering old joists
Greetings,
I’m at the point in my attic renovation where I have the old sub-floor removed and everything cleaned up. (pics attached) I’m asking for advice on the best way to level and strengthen the joists for new plywood. I’ve pulled string lines using the highest corner as reference baseline.
The joists are old school 2×8 (actual) and they are notched over the top plate and ribbon. Let me say that these beams are looking pretty old and brittle and very saggy. The house was built in 1901-ish.
My original plan was to sister all of these joists to the string lines using 2×10 which are 9 and 1/4 actual, notching them back down to the level of the string lines at each and, and shimming if I’ve got any real outliers.
Questions:
1. Am I doing this right?
2. What about plywood as a material? I’m seeing this being used in some cases.
3. To glue or not to glue? To screw or to nail?
Thanks in advance. Taunton rules.
Matt
Replies
You are on the right path. I would use lumber vs plywood. Also, remove the cross bridging and reinstall new cross bridging (or blocking) after, so you can have the new lumber span the full length. Also, make sure to crown the new lumber up. For ease I would use a nail gun with proper nails and nail schedule. Might want to use the occasional screw to pull boards together for tight connection.
“[Deleted]”
a big job. take it slow if you can
Do you have access to a laser level to see how much difference you have between the high and low spots around the entire room? I'm questioning whether the sistering is worth it and instead would consider a double-layer of 3/4 floor sheathing.