Particleboard underlayment and hardwood flooring

[areevesnc]

I’m planning to install solid hardwood floors in several rooms in my house. I checked a couple of the smaller rooms before starting, and found plywood subfloor under the old carpet, which I was happy with.

Much to my consternation, I’ve now discovered that the largest room has 1/2” particleboard (not OSB) underlayment on top of original solid wood floor material (I suspect that this layer is at least 80 years old). To make matters worse, the particleboard is very thoroughly glued down, which would render removal nearly impossible.

I know that installing hardwood over particleboard is… less than ideal. I’m wondering, though, what everyone thinks (or has experienced) with holding power of floor cleats through the relatively thin underlayment layer and into the more solid substrate below.

Another option might be to install a new layer of plywood or OSB over the particleboard to give cleats something else to bite into. This would make for a couple of odd thresholds/transitions between a couple of other rooms, but could probably be made to work.

Any comments or suggestions would be welcome!

Thanks!
Aaron

 

[Oka]

Remove the particle board, extra work & extra cost but I have learned to only use either a min 7-ply underlayment or MDO (a waterproof MDF).

My 2-cents

 

[tvrgeek]

PB glued over solid subfloor. Sounds OK to me IF it does not have any water damage or is a room where it is likely. Adding another layer would not seem to be any advantage and make transitions that much harder. Removing it would mean removing the original floor. So it is not perfect. Prefect would be 1 inch ply T&G screwed and glued to the framing. But do you live in "Perfect", or the real world? Just make sure your nails are long enough. That may be the hardest part. I guess you could mop it with a shellac or something to make it water resistant. I would not.

 

[Martin Roper]

I would be tempted to demo the whole floor, wooden boards and all, and start over. Run a circular saw between the joists and pry up the pieces. It would be a lot of work, but the floor would be level.

 

[Alan in Little Washington]

My floors are standard 2 1/4" X 3/4" T&G oak flooring nailed with cleats to a 3/4" sub-floor of high-density, water proof Advantech which is much tougher than standard particle board. The cleats hold well enough, since there really isn't much to cause movement. I don't remember how much sound came from the same style oak over 1" X 6" solid wood subfloor layed on the bias in my last house, but I have some creaks in this one. Creaks could be caused by non-acclimatized planks or the installer's habit of only nailing every few rows of oak flooring rather than every plank?

Are you sure the underlayment is 1/2 MDF? It seems to me you would have a difference in floor elevation between the larger room and smaller ones? Is the larger room a later add-on? What is under the wood layer- ceiling of finished room? open joist bays above unfinished basement? Do you know the condition of the original sub-floor? Could it have been damaged?

 

[areevesnc]

Thanks for the replies. It is definitely 1/2” particle board over solid wood subfloor. The house has been added to and modified numerous times over 80-100 years, so it has a few idiosyncrasies, to say the least. The existing subfloor — from what I can tell from the underside, in a 90% finished basement — looks to be in good shape. I suspect, given its history, that it might not have been as smooth as desired on the top side, leading to the installation of the particleboard under carpet.

The particleboard is very well glued down. Based on a little initial testing, removal would be very slow and mostly in the form of dust. Given the history of the house, I’m hesitant to tear out everything down to the joists. The existing subfloor material is solid and stable, and I don’t want to find further surprises that might make the job even worse.

Ultimately, my objective will be to replace almost all existing surface floor material with solid hardwood: I don’t like carpet at all. Having thought about this and taken some measurements elsewhere, I’m less concerned about a couple of transitions between floor heights, as these won’t be permanent: in the long run, I can build up everything to the same height.

Having considered everyone’s suggestions and continued my own research, my current thinking is that adding a high-quality layer of material with better nail holding power than particleboard is the way to go. I’m still interested, though, in other thoughts/reactions.

Thanks!

 

[Alan in Little Washington]

It would still be a lot of work, but you might be able to remove most of the 1/2 particle board by making (a lot of) controlled-depth (1/2") cuts across the entire surface with a circular saw. If not all, it might remove enough of the particle board so you could attach ply without any additional removal. You might get lucky and find some areas that are not glued down or not glued down well. You could test this method over a small area. Did they use screws or ring shank nails along with glue to attach the particle? If so, to save the blade you would need to avoid the screws/nails.

 

[Oka]

Here are some thoughts for you

Most my projects are med size projects as a Sr.Pm/Proj/Ex. in the 20-50million world. In these projects when they go over existing wood, they usually demo out to the subfloor, use a cementitous type of leveling compound on the subfloor after removing/fixing defects, then apply either a Baltic birch type ply, or one of the composite style approved subfloor sheeting. These can be epoxy treated OSB to MDO (water proof MDF), just depends on the design team. One thing to remember, most creaking is usually due to wood moving across a loose fastener. So, after demo carefully check the fasteners and re-nail or screw suspect areas.

Good luck

 

[Wilsoncb]

I can understand not wanting to remove the old floor. Have you tested how well the PB holds the nails you plan to use? Seems like you could nail all the way through the PB to the hardwood below it? Also, is it an option to use an engineered type flooring that could be glued? Perhaps a combination of glue and nails?

 

[Rwe2156]

Some experience, but not an huge amount. I’ve nailed flooring, glued flooring and snapped flooring together. I’ve sanded it, finished it, refinished it.

So FWIW I agree with the previous poster. What are these cleats you’re talking about? Something new?

Normally you would just use a staple or nail long enough to penetrate to the subfloor.

Nowadays I can’t see any reason not to use engineered flooring that requires no nails.

And I know one thing — I’ll never install another raw wood, nailed floor.

And I will NEVER again glue any flooring down.

 

[areevesnc]

Thanks again for the comments and replies. I’ve done a little more testing, and I’m not entirely happy with the way the particleboard holds flooring cleats. It may be perfectly fine, but I’m nervous about the long-term prospects for a new floor (which will be the last that I intend to install in my lifetime). I’ve tried a few other approaches to removing the particleboard, but it is glued down quite thoroughly.

The good news is that it is smooth, and should provide a good substrate for an additional layer of subfloor material (glued and screwed to the existing surface) which will hold floor nails better. The height difference will be quirky for a few years until I can re-do all of the floors, but I can live with it until then. I think that’s going to be my best option. I suppose I’ll find out!

I appreciate the ideas and suggestions, as always.

 

[Rwe2156]

Thanks again for the comments and replies. I’ve done a little more testing, and I’m not entirely happy with the way the particleboard holds flooring cleats. It may be perfectly fine, but I’m nervous about the long-term prospects for a new floor (which will be the last that I intend to install in my lifetime). I’ve tried a few other approaches to removing the particleboard, but it is glued down quite thoroughly.

The good news is that it is smooth, and should provide a good substrate for an additional layer of subfloor material (glued and screwed to the existing surface) which will hold floor nails better. The height difference will be quirky for a few years until I can re-do all of the floors, but I can live with it until then. I think that’s going to be my best option. I suppose I’ll find out!

I appreciate the ideas and suggestions, as always.

Please explain what these "cleats" are. Thank you.

 

[areevesnc]

Please explain what these "cleats" are. Thank you.

These are the typical L-shaped cleat nails used for hardwood flooring as an alternative to staples. I’m sure you’ve seen them, but may know them by another name:

Cleat Nails vs. Staples: An Overview - Hardwood Floors Magazine

What type of fastener should you use to secure hardwood flooring? Two common options are cleat nails and staples.

hardwoodfloorsmag.com

 

[Ricksmi]

I have changed, modified, replaced, and updated flooring in every house I have lived in and FWIW I have always called flooring nails "cleat nails" since that's what they technically are and never seen any other names for them. I do prefer cleat's to staples. And I agree 100% with another post about not gluing hardwood did that once and never again.

 

[Rwe2156]

These are the typical L-shaped cleat nails used for hardwood flooring as an alternative to staples. I’m sure you’ve seen them, but may know them by another name:

Cleat Nails vs. Staples: An Overview - Hardwood Floors Magazine

What type of fastener should you use to secure hardwood flooring? Two common options are cleat nails and staples.

hardwoodfloorsmag.com

Forgot that. OK so a 2” nail wouldn’t work?

I was surprised to find the heart pine floors in our house are nailed with 1 1/2 concrete cut nails. Even mor surprised there were no loose board and no noise. Roofing felt underneath.

 

[areevesnc]

If I’ve done my figuring correctly, a 2” cleat nail, driven into the tongue of 3/4” wood flooring and then through 1/2” particleboard underlayment at a 45-degree angle would catch just over a 1/2” of the solid subfloor beneath. I’m a little worried that that’s not enough to provide long-term stability, given the weakness of the particleboard layer and possible movement of the floor.

It’s entirely possible that I’m overly concerned, but I have encountered a few stories of floors that have buckled quite soon after installation.

 

[Ricksmi]

Forgot that. OK so a 2” nail wouldn’t work?

I was surprised to find the heart pine floors in our house are nailed with 1 1/2 concrete cut nails. Even mor surprised there were no loose board and no noise. Roofing felt underneath.

I have remodeled several houses over the years (OK decades) and found houses over 50-60 years old have had interesting quirks, pine flooring held down with standard finishing nails, oak flooring in my house in Richmond (built 1965) where it seemed they used on the flooring what ever nail was available. If it was not for needing to replace some boards from damage I would have never know.

 

[bphaynes]

I had this problem 2 years ago when I had someone install hardwoods in our house. We had carpet in the living room with 5/8 particle board under it. I ripped it up, which was not fun, but it was the right call. If you do I would suggest making sure it will transition with other rooms since my GC put down 1/2in osb in place of the 5/8 particle board and now there is a noticeable transition.