Hardwood floor Part 2- one last question

Eric Dellamater

Eric Dellamater

Well-known member
Tore up the carpet in the dining room, the subfloor was 3/4" particle board, not tongue and groove ply or old planks.

1. Is that sufficient to nail to or should I either rip that up and re-lay proper subfloor or do I just go over the top with another layer of ply. I may have to raise it 1/4 to match the kitchen anyhow. What do you guys think?
 
That depends, is the particle board on top of some thing else or just the joists. Check to see how level the floor is. Particle board has a tendency to bow or sag if just by itself. Some houses had boards at a angle and ply or particle board on top to level the floor. In that case the floor should be quite level. You hardwood floor will be just a level as whats under it. Another thing to be aware of is does the floor squeak when you walk on it. Now is the time to correct that if it does. I prefer screws to nails to correct squeaky floors along with wedges and white glue as needed.

I tried to find out the name of the company in White Lake Wi.and their Telephone number. They manufacture top quality hardwood floors. So I could find out what they seal and finish there floors with but no luck. They changed their name.
 
OSB (big chips) = Acceptable

Partical board (like pressed chainsaw dust) = Not acceptable

Back in the 70's it was common for homes around here to be built around here with 1/2' plywood base and a layer of 1/2" to 3/4" of partical board over it. When I was first getting into business for myself, I went over a floor that that the 1/2 - 1/2 combo reasoning the 2" nails would penetrate into good plywood. I was wrong! Within a few weeks, walking across the floor sounded like a bowl of rice krispies. It turned out to be the first and only job I ever ate. Fortunately it was only a small room. Never again!
 
First I assume that the subfloor is OSB (oriented strand board) of which there are numerous brands and qualities. Most are inferior to plywoods, however some in my opinion are superior. Some of the higher quatilty OSB's deflect less than almost all T&G plywoods and there nail holding capabilities are also superior.

These more expensive OSB products are designed for resisting water damage during construction, are much denser and heavier than other OSB products. The span ratings for these sheeting products are designed for larger spans of engineered floors (floor trusses, TJI's).

Take a look at the 8' joints they are almost certainly T&G. If they are not then I would recommend cutting a "whole bunch" of 14 1/2" blocks and blocking under all joints from below if possible.

Otherwise, I would sand any swollen joints (more prevelent on inferior OSB). Screw sheeting down sqeaks or not. Apply tar paper to floor. Install flooring perpendicular to joists.

As fat as 1/4 underlayment I see no significant structural improvement considering the cost though it may help you to flush out with other flooring such as tile on 1/2" cement board.

Hopefully this helps.
 
Further inspection shows Paul is on the money. 1/2 ply tongue/groove with 5/8 PARTICLE board NOT OSB

So, rip up particle? I need to raise the dining room 1/4 to match the kitchen. Suggestions?

I do appreciate the help guys.
 
Eric.
Considering the time and effort you put into sawing. planning and routering that custom wood, you are best off doing it "right". I would pull the underlayment and with any raised floor, verify the condition of the sub floor. Verify from both below and above and check the joists at the same time. I would instill a moisture membrane between the new underlayment and subfloor and install new undrelayment that is appropriate to your area. Installation wise I would go with a bead of glue and nail install. The reason for a bit of glue would be to prevent the squeaks and add an extra level of permanence (I overbuild).
Good luck, let us know how it turns out.
 
The particle board HAS to go. Once you get it torn up, go ahead and address any squeaks in the 1/2" plywood before putting new plywood over it. You will be tempted to think that by screwing through both the new plywood and the existing plywood that it will firm everything up and eliminate any squeaks you may have. Don't count on it.

Get good fir plywood to replace the particle board. You will most likely have to go to a lumber yard to get it. I've found that the stuff Home Depot, Menards, Lowes sells sucks for this application. The stuff I get is 5 ply and much more rigid than the three ply stuff. It costs a bit more, but it worth it to not have to fight a piece of cheap plywood that doesn't want to lay flat.

Once you tear up the particle board, you may find the plywood to be sagging in places or squishy. Pay particular attention to the areas where two boards meet. You may need to put some braces in between the joists in some areas.

When you put the new plywood down, be sure not to have the joints line up with the existing plywood, and to run it long ways across the joists. This is the strongest direction of the plywood. It should be that way now I'm guessing.

I like to use PL400 deck and subfloor adhesive between the layers. For what it costs compared to the rest of you materials and the time you'll have invested, don't skimp. Put down twice as much as you think you'll need. Cant have too much. I also use this adhesive to glue down any hardwood plank that will be facenailed as well as stairnoses, reducers, etc.

For raising the dining room. Is it the area that you have to remove the particle board? If it is, just get 3/4 vs 1/2. If not, just build it up 1/4. If it is a solid and sturdy floor already, OSB is fine. You dont really need the additional strength.

Keep us posted,

Paul
 
Terminogy aside, is your existing structure stable? Ripping out your sub floor structure to bare joists is a pretty radical thing to do.

Don't you have any friends who are pros, in the trades? One of them could look at it.

If your house was built to "code", has never been flooded (how else could the sub floor be squishy, sagging & the materials expanding at the joints. This happens with roof sheathing but mostly when ventiliation inadequate & the whole roof structure gets "cooked") hard to see a reason to rip everything out.
 
My dining room right now is particle board, solid, no squeeks, no significant deflections (although at 6'4" 280 I make most floors deflect some). Plan to rip it out, leaving the 1/2" ply underneath. Put in 3/4 t/g 5 ply along the stringers with glue down and screws. Will start after Easter.

Paul, good point on the face nailed boards, thanks. I hear you on the particle and stable 1/2 layer. I will screw it tight before the next layer. I hope I don't need many if any braces since access is limited in the basement.

Gary, no friends in that trade, that is why I am asking here on this board. The house, floor is stable NO water damage ever. Ripping out the particle board does make sense to me though given the holding strength of particle board to staples or nails. I have seen way to many fastners just pull out a chunk of the particles so I don't want that underneath my floor.

Derek has mentioned commercial underlayment several times. I went and check them out last night, they are way thicker than I thought. What is the advantage of having that thick of underlayment? cushion? I guess then I would ask what is different than vinyl flooring (which I will be pulling out, no fear, just asking though)?

I have the dining room handled, now the bigger question for my wife and I is do we want to hit the kitchen too or hold off. That room will be significantly harder to tackle.

Thanks again for everyones replies and interest.

Happy Easter to all.
 
Eric- I originally thought your house was a raised foundation over grade - didnt realize it was over a basement. Since it is, you wouldnt need to worry on the moisture barrier of a commercial membrane. You could go with a thin foam lining, similar to what they put under lam floors and call it ok.
 
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