Hardwood flooring over particle board subfloor?

[Dan Friedrichs]

I'm tearing up carpet and putting down 3/4" solid hardwood, but have found that the subfloor is 3/4" particle board (yes, particle board, not OSB) on top of 1/2" plywood. From googling, I've learned this was common in the 70s-80s to bring a carpeted floor up to the same level as other tile flooring.

So, what to do?

I'm know the "right" thing would be to tear the particle board out and put down 1/2 or 3/4 ply. But that's a huge amount of additional work and cost.

I've read that some people will nail the hardwood down to the particle board, so I guess that's the other option. I was planning to use Primatech cleat nails, 2", which are barbed, and should go all the way through the 3/4 particle board, 1/2 ply, and 3/8" into the joists (which I'll try to hit, and will run the flooring perpendicular to).

I will only be in the house another ~4 years, so am not necessarily looking to do this the same way that I'd do this in a "forever" house. Existing wood flooring in the house is already pretty squeaky, so I'm willing to accept that potential bad outcome. I'm not worried about water wrecking the particle board. That said, I don't want to be the jerk who does it wrong and makes a mess for later.

If this was your project, what would you do?

[andy bessette]

...I'm know the "right" thing would be to tear the particl board out and put down 1/2 or 3/4 ply....
I will only be in the house another ~4 years, so am not necessarily looking to do this the same way that I'd do this in a "forever" house...
I'm not worried about water wrecking the particle board...

If this was your project, what would you do?

First thing I'd do would be to fire you.

[Tom M King]

I would take the particle board up. How is it fastened down?

[David E. Hutchins]

I definitely would not put hard wood on particle board.

[Ken Fitzgerald]

Dan,

I think by your statement, you answered your own question but don't want to accept it.

[Bill Dufour]

What is under the wood?

[Dan Friedrichs]

If I were to install the hardwood on top of the particle board, the finished assembly would be 3/4" solid wood, 3/4" particle board, 1/2" ply, and barbed cleats running through the entire sandwich and out the other side into the floor joists. I have a hard time believing it wouldn't be stiff enough. I worry about the pull-out strength of cleats in particle board, but since the cleats go all the way through and through another 1/2 of ply, certainly that has some holding strength?

I don't feel good about it, but I'm trying to understand the problems that may arise so I can make a decision based more on logic and facts than feelings.



First thing I'd do would be to fire you.
Thankfully, I'm both the boss and customer on this one :)

[Pat Barry]

I'd like to understand what the issues are with nailing the hardwood floor on top of the particke board? What can go wrong?

[Ken Platt]

I'm wondering about the depth of penetration of those cleat nails. The ones I used when I put in floors (in my house) went in at an angle, so they don't go 2 inches deep. If my math is correct, and the cleats go in at a 45 degree angle, that gets them 1.4 inches down, which means only about halfway into that 1/2 inch plywood, and well short of the joists. If the hardwood flooring boards are perfectly flat, and don't need much holding, that'd be fine, but I found (only 3 rooms worth of experience, though) that a lot of the boards weren't so perfect. Would cleats mostly in particle board hold unruly boards?

But perhaps my math is off or I'm missing something. Wouldn't be the first time:D

Ken

[Tom M King]

When I started building houses in 1973, for a living, this is the way they were typically done for a couple of decades, so I have some feel for the materials. I'm assuming that the thickness of the floor below the tongue, and the angle of the cleat is accounted for (edited to add: I typed that before Ken had posted his response, which included the math). The cleats have barbed sides. The holding strength that the particle board will offer will approach zero. 1/2" sheathing plywood, which is not really a half inch thick, whether 3-ply, or 4-ply, will not have much better holding strength than the particle board. That leave the 3/8" in the joists, at best. That's the little pointy end of the cleats.

Knowing the stiffness of this flooring system, which has been increased in later decades, even in the cheapest built houses, it's going to flex some between the joists in the process of living on it. Things will loosen, and squeaks will be terrible. They were bad enough with flooring installed on thin subflooring, without the particle board.

I always snapped lines, and put every cleat in a joist, which also added another factor in selecting boards to lay out in each row, so that no two ends met towards the middle of the span between joists.

I just don't see anything good happening for the future of a floor installed on top of 1/2" sheathing, and particle board underlayment. That old particle board underlayment is even sorrier than what particleboard furniture people might be familiar with these days.

This just my opinion after a couple of decades of experience with that type of construction.

Only recently, I've seen the biggest shift in desired flooring ever. There are two million dollar houses built these days, on the lake here, with nothing but luxury vinyl all through the house. This just in the past few years. I almost always used 5" White Oak solid wood for floors in the spec houses I built here for 33 years, but built my last spec house in 2007.

[Edward Dyas]

As long as the particle board is in good condition I don't see anything wrong with putting a hardwood floor over the top. It would probably be best to run the flooring perpendicular to the framing in case the sub-floor ever gets wet. That would be the only issue. If the particleboard gets rotten the flooring could sag between the framing if you run it parallel. I just did a remodel where the pine 1x6 sub-floor was rotten and they took up the hardwood floor and people were stepping through the sub-floor. If they hadn't taken up the hardwood floor nobody would have ever known there was an issue.

[Dan Friedrichs]

When I started building houses in 1973, for a living, this is the way they were typically done for a couple of decades, so I have some feel for the materials.

Thanks, Tom. You perspective and experience are very much appreciated.

[Art Mann]

Where I live, solid hardwood flooring has fallen out of favor. Instead, people are choosing "engineered" hardwood planks, and the "luxury" vinyl that Tom mentioned. I used the engineered hardwood in my new house and have been very pleased. I much prefer it to the solid red oak flooring in my old house. It doesn't squeak and it doesn't expand and contract showing cracks with the change in seasons. If you don't remove the particle board, I would suggest the use of that material, which is glued down rather than nailed.

[Jason Roehl]

Rent a toe-kick saw, cut the particle board around the edges, then dig up all the nails holding down the particle board. BTDT--it's a LOT less effort to dig nails than to try to pry up the particle board. It will just break into small pieces. I would then glue and screw 1/4" OSB (1/2" plywood would be much better) through the subfloor into the joists.

And I second the comment that particle board has zero holding strength. I helped a friend and his FIL lay hardwood in a modular home. Someone messed up a few pieces, and I remember that we were able to just pick up the offending pieces by hand even though they had already been nailed down (with 2" cleats).

[Lee Schierer]

Are you sure there is 1/2" ply under the particle board? There are some houses I've seen where the subfloor is only 3/4" particle board that was glued to the joists.

[Tom M King]

1/2" plywood was the standard subfloor, for decades, after they stopped using diagonally laid 1x boards.

[Robert Engel]

If the issue is just nail security, what if you nailed the floor down with fasteners long enough to purchase the joist? It could mean doing it by hand, but its an option.

After reading Tom's post, have you considered a glue down floor? What about the vinyl with a 1/4" underlayment?

.

[Steve Rozmiarek]

From a contractor perspective - Flooring changes, you are doing it now and someone else will later to. There isn't a realistic reason to assume that this floor will be forever permanent, to be lived with by you or your relatives, and the next owner will probably change it to whatever is popular in 10 years anyhow. To that end, the nails in the particle board will last just fine for that long. I'd nail the subfloor to the joists better if there isn't a nail every 8" or so, then nail the wood down. People forget how much stiffness nail down wood adds to a floor, you'll stiffen it substantially, especially if you go across the joists. What the trade does with squeaks if they show after install, is face nail and touch up. The cleats won't go much deeper than slightly into the subfloor below the particle board, so making sure it's attached to the subfloor is important. I'd add a layer of paper underlayment to, probably just rosin, depending on the wood.

[Dan Friedrichs]

From a contractor perspective - Flooring changes, you are doing it now and someone else will later to. There isn't a realistic reason to assume that this floor will be forever permanent, to be lived with by you or your relatives, and the next owner will probably change it to whatever is popular in 10 years anyhow. To that end, the nails in the particle board will last just fine for that long. .

I really, really hate this, but I am leaning this way. If this were a house I was planning to live in long-term, I'd tear up the particle board. But career plans leave me here for about ~4 years, and it's otherwise a typical 80's house with vinyl siding put over the original T-11, a new layer of shingles put atop an old layer, popcorn ceilings covering bad drywall jobs, etc. I know that tearing the particle board up is the thing I ought to do, and if I were doing a total gut job I'd gladly do it, but if nailing to the particle board will last ~5 years...

[Dan Friedrichs]

I'm wondering about the depth of penetration of those cleat nails. The ones I used when I put in floors (in my house) went in at an angle, so they don't go 2 inches deep. If my math is correct, and the cleats go in at a 45 degree angle, that gets them 1.4 inches down, which means only about halfway into that 1/2 inch plywood, and well short of the joists. If the hardwood flooring boards are perfectly flat, and don't need much holding, that'd be fine, but I found (only 3 rooms worth of experience, though) that a lot of the boards weren't so perfect. Would cleats mostly in particle board hold unruly boards?

But perhaps my math is off or I'm missing something. Wouldn't be the first time:D

Ken

Ah, I hadn't thought about that. You're right - it'll only go half-way into the 1/2" ply.

[Tom M King]

The luxury vinyl doesn't even nail down. It snaps together like laminate does, and lays there. You could even take it with you when you leave. There are even versions with real wood surfacing. I have no experience with any of this stuff, but we are getting ready to take up the carpet in my Mother's 1960's house, and put luxury vinyl down, so I will have some experience shortly.

My Mother is 103, and going into assisted living, so we are going to start renting out her house. For that, the luxury vinyl seems hard to beat. Our bank even has it in their newest building now, for over a year, and it still looks like it was just installed. Our dog room is due for a new floor, so that's what we're going with in there too.

[Dan Friedrichs]

Update:

I can see the layers (the particle board and ply) through a floor vent register that I removed, but my eyeball thickness measurements were off. The particle board is actually 5/8" thick, and there's 3/4" ply under it.

Does that change any opinions?

[Rob Charles]

On Dan's original question on the particle board. A couple questions come to mind.
1. What is the spacing of the floor joists? What is their depth & span? How do the compare with current code for the area load rating?
2. How much deflection (bounce) are you currently getting in the floor?
3. What is the condition of the particle board? Pristine? Water damaged? Swollen areas?
4. What location/climate is the house in? Arid? Wet/damp south east? What is under the floor? Conditioned space? What I a getting at is the moisture transfer. What is the probability that the particle board will pick up moisture once your new floor is on top of it?

Pulling up the particle board is a pain in the rear. But, with a good breaker bar, crow bar & shovel, it is not too bad. Unfortunately, I have pulled up a couple in the system you have described.

Personally, I usually don't mind doing something once. I hate having to redo a project because I cut corners or didn't do it right.

From the outside looking in, if the floor system joists & sub-floor, the 3/4" ply, is in good condition & stable, especially if the space is 16" oc, I think I would be inclined to pull up the particle board an just overlay it with the hardwood per the normal practice in your local.


On LVT, that is great stuff, especially the high end & commercial grade stuff for many applications. I have it in several rental applications & it is holding up wonderfully. But, for my own house, I will stick with real wood floors. But, if & when I go into a condo, or the like, I will go with LVT over WTW carpet any day. I have pulled up too much carpet in my time and am always disgusted at how much dirt it holds.

[Lloyd McKinlay]

The National Wood Flooring Association subfloor guidelines can be found in chapter 4 https://fermaflooring.com/wp-content/uploads/2016/05/NWFA-Installation-Guidelines.pdf

I assume you will use the hardwood floors as a feature when you sell, seems like it should be done properly.

[Steve Rozmiarek]

The luxury vinyl doesn't even nail down. It snaps together like laminate does, and lays there. You could even take it with you when you leave. There are even versions with real wood surfacing. I have no experience with any of this stuff, but we are getting ready to take up the carpet in my Mother's 1960's house, and put luxury vinyl down, so I will have some experience shortly.

My Mother is 103, and going into assisted living, so we are going to start renting out her house. For that, the luxury vinyl seems hard to beat. Our bank even has it in their newest building now, for over a year, and it still looks like it was just installed. Our dog room is due for a new floor, so that's what we're going with in there too.

Tom, I've used the thinner stuff a lot, around 3/16th thick, but I just got three pallets in for a customer (8500 pounds!!) that has the pad attached. Closer to 3/8". It's heavy stuff, looks like it will last a long time. Not looking forward to lugging it around though.

[Robert Engel]

The luxury vinyl doesn't even nail down. It snaps together like laminate does, and lays there. You could even take it with you when you leave. There are even versions with real wood surfacing. I have no experience with any of this stuff, but we are getting ready to take up the carpet in my Mother's 1960's house, and put luxury vinyl down, so I will have some experience shortly.

Dan,

Why not just go with a floating floor? We did this in a room about 10 years ago as a "temporary" & it still looks good.

[Jim Andrew]

Helped my son remodel a house they bought a few years ago, has 1/2" particle board over 1/2" ply, and had the same in the master bath. We tore out and expanded the master bath, and replaced that particle board with ply. They did not want hardwood flooring, and bought laminate flooring, which looks like walnut. We had to tear out the flooring in the entryway, including the plywood, which was 5/8" to make the floor level so the same flooring could go throughout the house. Most of the particleboard in the house stayed.

[Frederick Skelly]

First thing I'd do would be to fire you.

What a nice (and useful) reply Andy!

[Mike Cutler]

I'm tearing up carpet and putting down 3/4" solid hardwood, but have found that the subfloor is 3/4" particle board (yes, particle board, not OSB) on top of 1/2" plywood.

If this was your project, what would you do?

Dan
I truly feel for you, and have been going through the same kind of stuff with my house for the past year or so. Every project I do, or repair I make turns into a giant pain in the behind because of what was done in 1978. ( The house was built in 1919, and a major overhaul was done in 1978.)
There are just things that should have been done then, with the house empty, that are very difficult now. It's very frustrating, expensive, and time consuming. I've ripped up the flooring to the joists in some cases. It just had to be done. ( In that particular case, 1/4" luan and linoleum, had been installed on top of a diesel fuel soaked T&G subfloor. You couldn't smell it, until I ripped up the luan. Man, it reeked really bad!!! The kicker, there hasn't been an oil fired furnace in our house since 1978.
My advice; Rip up the floors and do it right. It will make everything else you want, or need ,to do later easier.

BTW. Lots of folks thought they would only be in their current house another 3-5 years. Sometimes that doesn't work out. ;)

[Bradley Gray]

+1 on what Mike said. plus, it is bad ju-ju to do bad work. Do the best you can.

[Tom M King]

When pulling up particleboard underlayment, it's easier to take it up intact. Here's my method. I walk around on knee pads, with a cat's paw nail puller, I drive it under the head of a nail with one blow of the hammer, a helper pushes the puller with his foot, leaving the nail head above the floor. When I get tired of being on my knees, using long wrecking bars, so we don't have to bend over, we go around, and pull the nails all the way out, dropping them on the floor. Once all the nails are out, a magnetic sweeper picks them all up, and drops them in a tossable container (junk cardboard box).

With all of the nails out, a flat bar to start the first edge up, and then it all comes right up, to be carried out in the minimum number of pieces. It really goes along fairly quickly.

The nail puller is pushed by a foot because it gets to be a tiring, odd motion for an arm with many repetition. Limit footsteps, and limit bending over.

edited to add: My Pulling toolbox weighs about 65 pounds, and it doesn't hold the stuff that's longer than 28". For particleboard, the blue, sharp, pointy ended Vaughn pullers would be my first choice. You can find them in a number of sizes in Lowes. You want the smallest end, that will go down in the particleboard the easiest, and still have a big enough slot to hold the nail, under the head. The big, wide headed ones will be much harder to drive down into the particleboard.
https://www.amazon.com/Vaughan-Bushnell-BC10-2-Inch-Puller/dp/B00004Z2WK

[mreza Salav]

I think the chance of your cleats getting to joists is nearly zero (not enough depth). Removing the 3/4" PB which might be glued down will be a big pain, plus smoothing/cleaning it up afterwards.
It was mentioned earlier but the "trend" is mostly towards engineered, which are installed with nail and glue (they call it glue-assisted). If your PB floor is secure (glued down and screwed) then going with engineered flooring and using glue as well might be a less risky option.

[Gregory King]

C'mon Dan, you're a Creeker. Roll up the sleeves and tear up that trash. Pop the base boards off and cut the edges with the dremel saw if the particle board runs under the interior walls. Now this a good chance to rescrew the inital ply flooring for squeaks. Lay down the second layer of ply c/w construction adhesive. Don't spare the screws. Nothing like a little sweat equity. Wish I was there to give a hand.

[Dan Rude]

If you have particle board and a water leak.....you just have soggier sawdust. I only use it in speakers and counter tops that are sealed. Dan

[Dan Friedrichs]

Thanks for all the feedback, everyone - it is genuinely appreciated (especially the critical feedback!).

I had decided to bite the bullet and remove the particle board, but then found the door frames are cut such that they'll be too short once the particle board is removed. So I'd either have to replace the door frames or buy ply to lay on top of the subfloor to make up for the height lost.

Thinking back to maybe leaving the particle board, I did some experiments - nailing flooring scraps to plywood or the particle board, and attempting to pry them up. There is less nail holding strength in the particle board, but it still was far from easy to pry the pieces up...

Going with engineered or floating isn't an option because I'm matching/continuing a solid nail-down flooring that the previous owners installed ~10 years ago.

Looking closer at that already-installed flooring, I found that they installed it over particle board. It's ~10 years old, and doesn't have noticeable squeaking or problems.

So, I don't like it, but given that I'm not deviating from the existing standard-of-workmanship, I'm going to add some screws to the particle board to tighten it up and nail to it.

I don't mind working on old houses, but I hate how difficult it is to limit the scope of a project. I'd have gladly pulled the particle board up if the door frames weren't cut short, but if I replace the door frames, then I should upgrade them to nicer quality, and, you know, the trim has some dings, so might as well replace that while it's off, then the window trim should get changed to match, but while I have that off....etc...

[Frank Pratt]

Given the scope of work & the 'proof of concept' 10 YO installation, I'd leave the particle board too.

[Travis Provin]

Dan, what did you end up doing? I am in the exact same scenario as you.

[Dan Friedrichs]

Dan, what did you end up doing? I am in the exact same scenario as you.

I put the hardwood directly on the particleboard, and now 4 years later, it's still solid and squeak-free. I do not regret not pulling up the subfloor. Note that I did find that the particleboard was only 5/8" and there was 3/4" ply underneath - this discovery definitely made me feel better about it.

I did add screws to the particleboard at joints or anywhere there was flex, and used high-quality 2" barbed cleats liberally.