We just bought a piece of lake property for summer use, and it has a 1986 mobile home on it. The previous owners didn't winterize it, and a pipe burst flooding the living room area. In a lame attempt to get the floor (MDF) in sellable condition, they did the following:

• patched the worst areas with small chunks of plywood
• used lauan to "fill" in the sagging areas
• used patchwork lauan to try to even the surface
• nailed said lauan with hundreds of flooring nails
• conveniently hid the mildew with all this

I am in the process of replacing all the living room subfloor, which appears to be 3/4" MDF that runs from wall to wall width-wise and is in 6 foot wide strips. It is glued and stapled to the floor joists. It is *extremely* labor intensive. Ugh.

The question I have is how to do the edges where my new flooring interfaces with the wall. The solution I've come up with is to saw the floor as close as possible along the walls that are parallel with the floor joists. Then I built out a supporting joist to accommodate the existing edge of the MDF and my new subfloor. I did this with one panel and it seems to be ok, but want to check with the pros for advice before I go too far. I am using long deck screws to secure the plywood.

The overall goal is to put carpeting over this new subfloor in the living room. The hallway, which I will also replace, will have vinyl sheet, so I plan on stapling lauan over the subfloor and filling the gaps for an even surface.

This is just for weekend use and possibly rental, so I'm not terribly concerned about getting it perfect. But I would like it to be done right so it lasts at least 15 years, so any advice would be appreciated. Thank you.

 

Most MHs come from the factory with 5/8" partical board. It might appear to be thicker as it swells when it gets wet. Assuming you have already started to install 3/4" - that's ok but it might not be the same thickness as the original sub floor when you meet up with it. You are using plywood for the floor this time, right?

While it's best to dig out the rotten floor under the exterior walls, that is a lot more work most will run the saw along the wall and just install new up to the wall. The only drawback to this method is the wall doesn't have all the support it ought to.

Adding floor joists where needed is the way to go

 

Yes, using plywood screwed to the joists. My approach for the joists under the walls is to support them with perpendicular joists to avoid roll. Regarding thickness, I may install lauan to bring the new floor up to the level of the old floor, but this is a weekend place, so I'm not overly concerned about getting it perfect...I just want it to be done well enough to last and be safe.

Thanks for taking the time to respond.