My wife and I are in contract to purchase a home (not a new home). The inspection revealed a few things and the seller has agreed to fix all but one thing we requested. The one thing they are not going to fix/address is a small area of wood rot in the OSB sub-floor directly under the front door. According to them, they can't seem to find someone to do the work. The small area of wood rot (about a 6 inch by 6 inch area) is visible from the basement. The basement is not finished and there are no signs that large amounts of water have entered the home from this area. I do know that the sub-floor has two layers of OSB/plywood and there is luxury vinyl plank on top of that. I remember the inspector showing us this and we went to the exterior of the front door and noticed small cracks between the bottom door sill and the stone/concrete underneath it but the inspector couldn't/wouldn't say if that was the source of the water entry.

Anyone experienced this before and have an idea how big of a deal this is? I'm not thinking it's something to let the deal fall apart over. I'm pretty handy so I feel I could easily replace a small section of the sub-floor myself and the LVP will make it even easier IMO. However I know things aren't always as easy as they seem. Any wisdom would be appreciated :) Thanks!

  • 1
    This could run like an old sock... what happens if the layer of osb that you cannot see is wet?
    – Solar Mike
    Commented May 15, 2019 at 13:01
  • Is it rot or swollen? Many times when people see OSB that has gotten wet they say rot when it’s not truly rotted , if just swollen it still is week and needs repaired but other materials are probably fine. If truly rotted expect other wood in the area to be rotted the glue mixture that holds OSB together makes it a little bit rot resistant so if truly rotted it could be a much bigger job a photo would be helpful.
    – Ed Beal
    Commented May 24, 2019 at 13:47

1 Answer 1


As you noted, it's possible the water came from the front porch, ran under the door sill, across the rim joist, and seeped across the subfloor, possibly between the layers, before showing up in the basement. Because any and all of these may have been wet long enough for the subfloor to rot, they should all be checked.

I'd start by probing all of the areas around the rot with an ice pick to find the extent of the soft, decayed area. If you can unscrew the sill or lift part of the vinyl planking you can come from the top. You can also probe from the basement up, starting in the obvious rotted area. Since you don't own the home yet, I doubt they'll let you drill exploratory holes or do other destructive tests, but some careful poking may tell you more about how much repair is needed. After repairing the wood, consider how toy would keep water from getting to this area again... pouring a new porch, adding an awning, grading the front yard, etc. Consider those costs when deciding whether you want to ask for concessions or accept the risk there may be more that you haven't seen yet.

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