Flattening, and sealing particle board sub-floor

[TwilightFenrir]

Well, I just bought a mobile home from my aunt, who has had the place since it was new. It's been under rent for the last couple years, and they pretty badly neglected the place, but most of it is cosmetic, the systems are still sound.

The biggest thing right now, are windows, the walls around the windows, and the sub-floor. I know what I'm doing on the first two, but I'd like some advice on the sub-floor.

I tore out all the carpet in the house, and there are these odd spots that apparently got wet at some point, and stick up from the surface rest of the surface of the sub-floor... Almost certainly from decades of keeping Rottweilers, and other dogs.

What I want to do, is put down some 3/4 tongue and groove plywood on top of it, and put some hardwood floors on top of that. So, I was thinking about renting a floor sander, grinding down the high-spots, and putting some sort of sealant on it before putting the new flooring on top of it.

Is this a decent idea? I'd rather not have to cut out all the spots and replace them, there's a lot of them. Can you seal particle board? What kind of sealant could/should I use? Thanks.

[bobfather99]

I would cut out any sections of flooring and replace with plywood. I just wouldnt trust any particle board that got wet at one time.

[Brenda (OH)]

cut out the sections, will be cutting out potential odor sources .....

Brenda (OH)

[TwilightFenrir]

Well... I understand your point... but, that's alot of sub-floor to cut out, in really random places... I shouldn't have to worry about the structural integrity of the floor, since I"m putting 3/4 T&G plywood ontop, that should redistribute the load to the good parts.

As for odor sources, it's so old it doesn't smell at all... besides, once again, I am going to try to seal it, which should stop anything from getting in or out. Also, there will be a layer of plywood, a layer of paper, and a layer of bamboo flooring on top of it, so nothing will get through...

If that's what I have to do, I will, but I would really rather avoid it if at all possible.

[Greg]

Hi & welcome. I understand you hesitation to do a patch job, but if you are going to do the job, do it once and do it right. Over time the subfloor will fall apart and leave you with NO support under the plywood. Add to that the "Door factor" that you will need to trim all of the doors to allow for the new floor height.

The job is not a hard job to do, but it is very time consuming. Greg

[JD]

Were you installing a floating bamboo flooring? There would be a dilemma if this is nailed flooring as the particle board is not a suitable subfloor. If the home is empty and the carpets are gone, I would consider replacing all of the particle board flooring with 3/4" tongue and groove. Maybe just the areas under the bamboo or other premium floorings.

Sometimes doing large areas can go surprisingly easy and quick. Depends on how bad the glue sticks to the joists.

JD

[TwilightFenrir]

Were you installing a floating bamboo flooring? There would be a dilemma if this is nailed flooring as the particle board is not a suitable subfloor. If the home is empty and the carpets are gone, I would consider replacing all of the particle board flooring with 3/4" tongue and groove. Maybe just the areas under the bamboo or other premium floorings.

Sometimes doing large areas can go surprisingly easy and quick. Depends on how bad the glue sticks to the joists.

JD

Which, is why I was planning to put the tongue and groove over the entire sub-floor, beneath the bamboo flooring. Basically, putting a sub-floor on top of the sub-floor.

I don't see how the particle board potentially giving way in these few small areas could possibly compromise the 3/4 T&G on top of it, since there would be far more support for it than on a normal sub-floor. But, since that seems to be the unanimous consent, and I'm new to carpentry, I'll be doing some patching before continuing. Still going to Killz it though!

Thanks for the help.

[joedirt63]

hey i'm in the prosses of doing that same thing with myy kids 88 zimmer, member while back i wrote about floor ? well i just finished a14x30 section of floor with 3/4 marine grade plywood, some guy had a bunch in his basment and i talked him into selling it to me. you can't find this stuff around here, last time i saw it in a lumber yard, yeah a LUMBER YARD , that dates me don't it. was 30 years ago. it wasn't hard to do just boreing, parical board turned too flakes, prob was this 8x6 closet between the kitchen and bedroom that housed the water heater gone evil,3 walls had to come down. anyway i used deck and porch paint to seal the floors,

[Groo]

Marine grade goes for $60+ a sheet when I looked into it

the particle board may hold moisture next to the T&G, but if its dry, I don't see how it would re-wet. As you are putting a stonger floor over a weaker floor, I dont see a problem with even just cutting those spots right out. and leaving a hole, if its not too big.

I've found my particle board and strips add up to the same thickness as finished 2X boards, so for my floor patching, its just zip along a line with the circular saw, drop it in and screw it down.

ps. I'd sugest just buying a 4x24 blet sander vs. renting a floor sander.

[JD]

One of the biggest problems with laminating plywood over a particle board floor is when there is a roof or plumbing leak, water can get trapped between the layers, which can rot plywood. Also the extra height of adding plywood on the top will create a problem with exterior in-swing doors swinging in and possible tripping spot at sliding glass doors. If you do choose to laminate the plywood over the existing floor anyways, I would certainly do a full glue between the layers to reduce floor squeaks.

I do agree with Groo on using a belt sander over a floor sander. With a pack or two of belts, the belt sander does a quick job on the humps and you have a lot more control of the sanding.

JMO
JD