Subfloor Installation 3 of 3: A Straight Edge for Siding

November 02, 2018

The floor system should not cause a bump in the wall

In the first few videos, we showed how to glue, flip, nudge, and nail sheets of the subfloor. In this episode, David will address the edge of the sheet, where it lines up on the outside wall.

This ensures a flat wall spanning the second floor that won't telegraph humps through the siding. On a first-floor subfloor installation, the rim can be glued as part of an air barrier strategy.

One way to pull the rim out is to drive a screw into it, and use your hammer claws to wedge it out. Sometimes that doesn’t work, and you need to pull out the big guns. He sends Calvin inside to push the rim out with a sledgehammer. But first,

David: We do not nail the end yet because that wall might have to move in a little bit here or there.
We spent all of this time putting our deck down on walls that were straight and plumb. But I just want to recheck that because we may have moved everything around.

So I put a level on there, and I see that I have a nice straight line, I have a good bubble, and my floor is there, back from the edge.

So I can measure off of this point now, like say, a three-inch mark, and I do that at the other corner, then I can snap a line through here and make sure that no point projects past that. So I’ll know that this wall is straight. It’s plumb at this corner, plumb at that corner, and straight all the way through, then we can nail it off.

Now here I can see that although this wall is plumb, this rim joist is not. I need to get that rim joist out that eighth-inch or so, so everything works.
I’ll measure off of my level. Right there is plumb, and it’s on my three-inch line, so I want to move that out.

One way is to partially insert a screw to use for leverage. Sometimes that doesn’t work, so you need to turn to a sledgehammer from below. To gauge movement easily, make a line on top of the rim.