2

Carpet has been removed and subfloor exposed and cleaned. The floor has been leveled to <3/16" out of flat over 6', primed to cover some pee spots, and is ready for the underlayment. The new flooring is solid 3 1/2" x 3/4" oak.

crude drawing of my house My initial plan was to use the south wall in the east and west bedrooms to lay a chalkline (red) between them for the starter row, some discrete number of 3 1/2" planks' distance from the south hallway wall, plus an expansion gap (thinking 1/2" at most, since my floorboards are less than 3/4" thick and I don't want to buy a ton of quarter-round).

The question: since subfloor sheets are screwed into the joists, and come from the factory square (assuming they weren't cut prior to installation), is it feasible to use the adjacent side of the subfloor sheets to square up the first line of flooring to the house? Would this be more accurate than using the walls, since I'm effectively squaring the first row to the floor joists rather than the wall?

I couldn't find record of anyone online doing it this way, but it seems logically sound. Eager to know others' thoughts. I suppose I could always do the wall way first and see if it's parallel to the sheets to check my work.

Thanks!

Improve this question
3
  • 3
    I think maybe too many assumptions, without careful measurement first. Most houses/homes will not be perfectly square/perfect 90 degree angles. You probably want a few chalk lines laid out in perfect squares, than picking one straight line.
    – crip659
    Commented Dec 17, 2023 at 19:29
  • No matter what, I'll be using a single straight chalkline squared up to some part of the house. I'm just wondering if it's better to square up to a common intersection of floor joists or two different walls on opposite ends of the house.
    – J.D. Mallen
    Commented Dec 17, 2023 at 19:54
  • 1
    I don't see the advantage. You have to chalk it anyway once you figure out your floor edge widths and lay any paper down, so you won't be able to see the sheeting lines. To check square, I'd use a laser with lines at 90 degrees. They are pretty cheap these days.
    – RG Hughes
    Commented Dec 17, 2023 at 20:58

1 Answer 1

Reset to default
5

Don't use subfloor seams for layout. Human perception seizes on out-of-parallel lines, especially if the lines are close to each other. This means that you want to minimize the flooring's deviation from parallel with the walls, especially if you've got a sliver running beside a wall.

Snap multiple lines, one for each wall that runs parallel to the floor seams, and label each line. Each line should run the full house length so you can compare lines for parallel. If there's no out-of-parallel deviation between these lines, then you lucked out. Your main problem now is avoiding slivers running beside walls. If there is out-of-parallel deviation between these lines, then the best you can do is maximize the distance between the closest floor seam and its corresponding out-of-parallel wall.

Don't forget that hallways tend to be free of furniture that would otherwise obstruct the perception of out-of-parallel. Bedroom and living room walls tend to be broken up by furniture. Parallelness with hallway walls (and other unobstructed walls) should therefore rank as more critical than parallelness with other walls.

Once you have it figured out, snap your main control line, label it, and clear coat it.

Improve this answer
2
  • Wonderful answer, thank you.
    – J.D. Mallen
    Commented Dec 19, 2023 at 1:33
  • @J.D., no problem. I read a book something like 20 years ago that turned this kind of stuff into common sense for me. There it is. Visual Intelligence by some guy named Hoffman. The "sliver" language comes from the tilers.
    – popham
    Commented Dec 19, 2023 at 1:53

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service and acknowledge you have read our privacy policy.

Not the answer you're looking for? Browse other questions tagged or ask your own question.