How to install hardwood floor over particle board

What you’ll learn

Last year, we installed solid oak hardwood floor in our main bedroom and family room. To our dismay, when we ripped up the old carpet, we found that the whole subfloor was covered with particle board. Using a standard nail gun to install the floor was out of the question–particle board isn’t structurally sound enough to “bite” nails.

Removing the particle board was impossible–it was completely glued down to the plywood. We ended up using screws instead of nails, making it bomb-proof at 3x the labor. Here’s a step-by-step how.

The particle board after ripping up carpet

The problem: nail length

Hardwood floor nowadays is manufactured as tongue-and-groove and quickly installed with a nail gun and standard 1.75″ length nails.

Hardwood floor is 0.75″ thick. If you’re nailing at a 45-degree angle, this would be a total of ~1″ before you get to the plywood (0.75″ x sqrt(2)). Since the nails are 1.75″ long, that’s about 0.75″ of nail to dig into the plywood subfloor, which is great.

If you have both 0.75″ hardwood and 0.5″ particle board before you hit plywood, you have nothing left of the nail to dig into the plywood.

You’re pretty much left up shit’s creek with no good options. You could (a) replace the whole subfloor, (b) have a hard time finding a contractor to take your job, then pay them an exhorbitant amount–we were quoted $15k for labor alone, or (c) suck it up and drill each and every hole instead of using a nail gun.

Materials

Hardwood

Somerset Floors

Engineered to be tongue-and-groove. FMD Distributors in San Jose, CA has great options and you can buy at contractors’ prices. It was <$6/sqft

Trimhead Screws

Amazon

They have a star head to prevent stripping.

Moisture Barrier

Amazon

Put this between your subfloor and the hardwood floor. It’ll prevent any moisture from leaking through.

Step 1. Rip out old carpet

Step 2. Lay down moisture barrier

Lay down Aquabar. It’s incredibly well marked for where to overlap. Only do a couple sections at a time.

Step 3. Lay out a row

With 2 people, it worked out really well to have one person as the layout-runner and one person as the driller. The layout-runner chooses boards for an entire row, tapping them into place, and cutting the last board to length.

Starting to lay out a row from a pile behind me.

No two board ends in adjacent rows should be within 6″ of each other. Staggering makes the fit much stronger.

Whack the groove of the new row into the tongue of the previous row. A scrap 2×4 works well. The screwheads make the tongue harder to fit in the groove, unlike nailheads.

Find a board a tad longer than you need for the final in a row.

Chop-saw to length. Note there’s tongue-and-groove on the short ends, too. Make sure you’re cutting off the wall end.

It seems like a perfect length to the wall. Note: the cut piece is actually off the wall end–the tongue is still intact where it’ll set into the previous board.

Use a crowbar to push the last board squarely into the previous of the row. If you cut the length perfectly to the wall before, the amount you’ve pushed in will leave a perfect 0.25″ gap for wood expansion in humidity.

Step 4. Drill pilot holes and drill screws

Unfortunate person #2 gets to drill holes every 6-8″. We found we needed to drill pilot holes, or the screws would crack the tongue.

Side view of screw heads into the tongue.

Step 5. Starting and ending a room

Starting a room is pretty easy–just put some door shims so you have ~0.25″ before the wall to allow for expansion. Ending is a bit more difficult.

Whacking with a 2×4 won’t work for the final rows. We made a jig that I could whack with a mallet.

You’ll have to use a table saw to cut the last row to width, then top drill. The last tongue is still intact, and required just a little bit of jiggering to set in place. Fill holes with Plastic Wood.

Plastic Wood

Amazon

Fills in top-down screw holes. Get the color to match your floor.

Step 6. Finish!

We found that we could handle only about 4hrs a day working on the floor–it’s a lot of being on your knees and drilling. The plus side of all that work is it’s bomb-proof. Good luck to the next person who wants to replace the floor!

There’s no squeaks whatsoever, and we don’t expect there to ever be. Whatever minor creaks were there initially are gone. We think any pressure on the floor actually helps screw them in tighter.

eidolem