Recently the wood transition strip at the door from my garage to the backyard came loose. When I pulled the transition strip it appears the underlying wood is rotted, how would I go about repairing this?

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transition strip

Edit: I'll say what what I know might be underneath. This is the ground floor. I don't believe out basement extends under any part of the garage. My garage has a tile floor installed by the previous owner (she ran a kennel out of house before we bought it so all the rooms, not just the garage, had this crazy tile!). I presume the tile is on top of concrete based on what I can see at other parts of the garage where the tile ends) The red brick is the outside of the house, and the pavers were installed directly on the dirt by the landscaper.

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    – HoneyDo
    May 13, 2020 at 15:33
  • 1
    What is under the wood? (Nobody can answer your question without knowing this so kind of nonsense that there are two answers without this knowledge)
    – DMoore
    May 13, 2020 at 17:12
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    That's not a transition strip. It's an adjustable threshold. This type is integrated with the door frame, which likely also has decay, as might the floor joists below. It's time for a new door and improved water handling, at a minimum.
    – isherwood
    May 13, 2020 at 18:07

2 Answers 2


To do it properly you're going to have to pull up that aluminum door sill to see what's going on underneath. It appears that water has been seeping under the door sill from the outside and has rotted part or all of the underlying door frame. It's also possible that the water is coming in along the perimeter jambs and seeping down to the sill. To remove the aluminum sill you're probably going to have to remove the door stop trim on either side of your door. If you do it carefully you can probably re-use it.
The sill may be glued or screwed on. This will expose the wood sill frame underneath. The wood sill will be attached to the jamb on both sides. It may all be rotted or just part.
To replace it you'll have to cut it out at the jamb on both sides or if it's only rotted along one length you might be able to remove the compromised part with a chisel. Let the area dry out removing any rotted portions. You can then replace/repair the wood sill with new wood by attaching it directly to the framing underneath as a support for the aluminum sill.
You can then reinstall the aluminum sill and the adjustable threshold that came up - you probably will want to replace it with a new one. it's critical that you weatherproof around the aluminum sill with exterior silicone caulk. You also should caulk the entire exterior perimeter of the door and it's trim and make sure the weatherstripping around the door, especially at the bottom isn't leaking. Until you weatherproof it the problem will only recur and get progressively worse.

  • What is exterior silicone caulk? Are you saying silicone is different if interior rated? Also how do you answer this question without knowing what is under the rotted wood? It is a garage. It could be dirt, concrete, or in between.
    – DMoore
    May 13, 2020 at 17:15
  • Wow! You're right. Using the word 'exterior' was unnecessary - it's silicone caulk. However, I clearly stated that the rotted wood needs to be removed. Only then will you know what's under it and deal with it. The pictures show that you step up from the pavers onto the brick threshold. It appears that the concrete extends up to the door sill . Odds are it's framed under the sill - maybe concrete - doubt it's dirt.
    – HoneyDo
    May 13, 2020 at 18:32
  • If a tube says exterior silicone on it - it could - this just implies that it is not supposed to be painted. There is no difference in effectiveness. Now there are other types of caulk that might have a different formulation to help with UV rays and outdoor exposure.
    – DMoore
    May 13, 2020 at 18:35
  • Understood! There is also paintable silicone caulk but that's another discussion.
    – HoneyDo
    May 13, 2020 at 22:17
  • thanks I'm going to go try to pull the aluminum sill and let you know what I find wish me luck thanks!
    – user117192
    May 14, 2020 at 16:50

oof; this could be a 5 min job, or a 5 hour job, or maybe a 5 day job, depending on how you want it fixed.

The quick fix is to scrape out the rot, fill with something like wood putty, and re-screw, maybe with longer screws, which should hold it for a while.

Better would be to replace the rot with a new board cut to size, then replace the transition.

Best would be to first fix the leak that caused the rot, then fix the symptom. I'm guessing there's no weather stripping along the door's bottom edge, call it a hunch. If that's not it, you might have a major problem with water rotting the walls and floors, and this is the tip of the iceberg...

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