Gotta go work on a rental house. Been vacant for a couple months during which time a pipe in BA #1 leaked. In the leak path, the MDF sheathing is Shredded Wheat . I’ve run into these before. This repair is straight forward, just a matter of how much floor gets replaced.
My question arises from BA#2. In this case we didn’t have a water leak. An opossum (freaking oversized RAT) had managed to infiltrate the house and crawled in between the shower and toilet to die. Would have been SO much easier if it had crawled into the shower and died…
But anyway, with unwanted guest removed, owner describes BA#2 damage as when he cut away the carpet in the BA (who the He11 puts carpet in a BA?!), there was a nasty, black (large opossum sized) stain on the MDF sheething. He says there’s no structural problem with the MDF, just a nasty stain.
My initial reaction is to put some kinda sealer on the MDF (to contain the stain), then put 1/4″ ply over the mdf and vinyl on top. Toilet will probably have to come up, but I’m hoping a horned-wax ring will seal to the higher floor.
Any recomendations on what to seal the ‘black spot’ with?
And opinions on the process… am I taking the long way round the barn by putting ply down? I don’t generally like to adhesive vinyl down to MDF, but maybe some kind of skimcoat would be better than ply? What are your thoughts?
Replies
JT, MDF?
Remodeling Contractor just outside the Glass City.
Quittin' Time
JT, MDF?
Pressed sawdust looking stuff. Typically if it gets damp, it warps real bad. If it gets wet for any period of time it turns into something with the strength of Shredded Wheat... just crumbles. And you SURE don't wanna step on it after its been wet!
On repairs, I've seen where people have put vinyl directly on MDF. At some point the MDF got damp and the vinyl lifted off. When you pull it up and look at it, there's MDF crud still on the back of the vinyl.
If you want a better idea of what it looks like, take a piece of 2" tape and dip it into a pile of sawdust. When you remove it, all the sticky part of the tape is covered in sawdust. That's kinda what the back of the lifted-off vinyl looks like, just not quite so evenly coated.
jt8
John,What you have there is particle board, probably the cheap underlayment grade. MDF is a different animal, and is seldom used in floors. Particle board has no business being in the floor sandwich of a bathroom, because of the swelling and the "shredded wheat" strength issues. Since this is a rental, I suppose the HO isn't prepared to pay for correcting the problem the right way. Maybe if you scare them about the black mold, they'll let you tear it all out down to the subfloor, which is wood or plywood, or the less-desirable OSB.Question for others: Would Advantek work well as an underlayment for vinyl, assuming the thickness worked out?Bill
Hey Bill. Technically, I think you might be correct. Technically the stuff probably is particleboard, but I tend to think of pb as small chips, not sawdust, so I will usually refer to pressed/glued sawdust as MDF. Crap by any other name still stinks. ;)
jt8
You can call it whatever you want, but to communicate with the rest of the industry, it works better to use the same words the rest of us do. That picture is particle board. Your description of it ( like wheat straw) is for particle borad. The installation location is for particle board. PB is or was often used in cheap housing for floor underlayment. ( I haven't seen it for ten or fifteen years myself) MDF was never used for flooring material, unless someplace by an unknowing hack or HO DIY.Anyway, If it were me, I would only take on the job if the owner were willing to pay for totaly removing the PB from the floor and replacing it. The fact that it was only cartpet over it in a bathroom tells me that it has suffered enough from moisture already, not even considering the non-vegetable critter staining, that it is on the way out.
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You can call it whatever you want, but to communicate with the rest of the industry, it works better to use the same words the rest of us do. That picture is particle board. Your description of it ( like wheat straw) is for particle borad. The installation location is for particle board.
That picture was MDF. I pulled if from a ply website, it wasn't a worksite picture. But you were correct and I agree with the remainder of your post.
I use ply for floor sheating, but in the future hope to give advantech a try.
Pic from (dial-up'per gonna love this one):
http://www.boulterplywood.com/ProductGallery_41.htm
jt8
Edited 11/21/2004 2:17 am ET by JohnT8
The page is still loaading. Looks like a good site that I will bookmark.But they could still have made a mistake in posting that photo. It does not look like any MDF I have ever seen. MDF always has a smooth hard surface, even the untempered is mare solid than that photo shows.
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Just finished loading.I apologize. That photo is indeed MDF. The full sized photo shows that the way it was cut on the edges left a texture that looked like particle board in the smaller photo.here it is
http://www.boulterplywood.com/photogallery/photo25568/mdf.jpgNow, which did you say was used on that floor?
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Now, which did you say was used on that floor?
I go work on it at the end of this week. I'll bring ya back a couple closeups. But it will turn out to be pb. Bit of sawdust and glue. Not suitable for bathrooms... and IMO not good for much of anything.
jt8
shellac the dickens outta the whole floor, 1/4" ply underlayment..vinyl away.
Spheramid Enterprises Architectural Woodworks
Repairs, Remodeling, Restorations.
Yeah, what Sphere said. Shellac is the most amazing sealant. And do the whole room, not just the spot.Unless you're the lead dog, the view just never changes.
shellac the dickens outta the whole floor, 1/4" ply underlayment..vinyl away.
shellac? There I am thinking someone is going to suggest some state-of-the-art new sealing substance... and what do I get ? Shellac. Shoot, shellac was old when Jesus was putting it on his tables.
jt8
Zinser makes two shellac based primers, one of which is white pgimented. Seals ANYTHING. We just covered crayons, water stains, deep colors, cleaning stains with it. Great stuff.And if you don't have ventilation or a respirator, you can get high from it...
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Question: Why shellac in a wet area? Isnt shallac prone to flake when water hits it vs poly or moisture cure?The secret of Zen in two words is, "Not always so"!
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Hymie, the shellac ought NOT ever see any water...it's just to seal in the possum leakage of bodily fluids. The new underlayment and vinyl and caulked baseboards is the real deal for the floor.
Spheramid Enterprises Architectural Woodworks
Repairs, Remodeling, Restorations.
Sure didn't look like MDF (Medium Density Fiberboard) MDF is smooth and heeeaaavvvvyyy. Either way I can't imagine them on a floor right over the joists! Seen plenty of 1/2" ply as a subfloor and then particle board to bring the level up to adjacent 3/4" hardwood flooring. If the particle board is screwed down about every 3" on the edges and 6" to 8" in the field, filler/leveler used on seams and recessed screw heads, it lasts surprisingly long. That would be with sheet vinyl. One piece or I've seen some seam sealer that literally welds the vinyl together. Subfloors seem to be all 3/4" T&G any more. Sometime two layers. Tyr