How do I level an uneven wood subfloor?

Question

My parents recently bought an 80 year old house with a small garage apartment we want to remodel. We ripped up the carpet as well as a layer of hardwood floor that had been laid over the original subfloor. The apartment had termite damage at one time and it shows in the subfloors as they are uneven due to the termites.

We want to put down a new plywood subfloor over the existing damaged subfloor and then lay down a laminate wood floor. This will bring it level with the other floors in the apartment.

What is the best way to level the damaged subfloor so that we'll have a flat surface to work with after installing the plywood floor on top of it? Should we use leveling compoud or some kind of padding? Thank you very much.

Answer 1

ardex

Answer 2

Rip out the old sub floor....you're going to install new, anyways.  Check to see how much the floor needs to be leveled, working off of the floor joists.  Rip some strips as thick as what the highest point needs to be, out of 2 by 4,6,8....what ever you have, and nail them to the lowest floor joist.  Rip what ever thickness strips you need to get the remainder of the other floor joists to be level.  You may need to check for level in a couple of locations.  If you don't have a table saw, have a friend with one rip the strips for you. Then install your new sub floor.  I leveled the floor in the bathroom and kitchen of my old house with this method....it turned out great.

Answer 3

If the original flooring has termite damage, I would rip it out and and replace it, especially if you only have a 12' by 12' space to replace. Leveling compound would require more work than removing the original flooring.

Use shims under the subfloor to bring it to level. If you have access to the joints, you can insert the shims between the joists and the original subfloor.

Answer 4

You need to do this leveling by cutting wood shim sleepers to fill in the low areas. Get a really straight 2" x 4" x 12' long. Cut it so it fits wall to wall perpendicular to the low spots. Leave your self about a 1" gap from the walls.

Now start against 1 wall and move it in a straight line ( one person at each end) across the floor to find the lowest dip in the floor. Let's say the lowest dip is 1/2" and most of the other dips are 1/4".

Go to the home center and buy a sheet of 1/2" plywood, and also a sheet of 1/4" underlayment (luan).

Rip some strips of each about 2" wide x 8' long. Also buy 3-4 tubes of liquid nails (heavy duty construction) adhesive in the small caulking tubes, get the caulking gun also if you don't have one. Buy a small box 5lb. of 1-1/4" ring shank flooring nails.

Now start your level 2" x 4" against the wall again and as you move it straight across the floor slide your plywood strips under the 2" x 4" until they are close or touching the bottom of the 2" x 4". Now slide them out, glue them, and slide back under 2" x 4" and drive a nail through the shim into the floor. If the dips gradually come out just cut off plywood strip where it starts to get too high. Move straight across the floor until you reach the other wall.

Now when you are done, measure where your new subfloor sheets will be laying, make sure you the butt joints of your 4' x 8' sheets will fall on a full pc. of plywood shim, or the floor. If not cut a plywood strip and place it at the butt joint so both sheets will land on the strip. You don't need to do this on the long sides of the new subfloor-just the butt joints or where the 4' ends meet.Mark your new subfloor and s***w it down only where you have shim strips or the floor is at the correct level, do not s***w it down where you have a void under the s***w.

The trouble with floor leveling compound is that is dries out, and if there is any movement in the floor,subfloor at all - it will crack and disentigrate. s***w down with a 2" deck s***w-use same liquid nails to s***w subfloor down as you used to glue shim strips.Stagger your joints in your new subfloor so no butt joints line up, usually stagger them 4' or half the sheet.You will need 5 sheets of subfloor - I would use 3/4" tongue and groove o.s.b. You will have no problems with it.

Answer 5

1 Take the subfloor out

2 Replace or repair damaged beam or beams

3 Put the floor down

you only have to repair the section not the hole floor