Home>Discussions>DOORS & WINDOWS>Moisture Ants Rotten Joist Header, Sill and Threashold
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Moisture Ants Rotten Joist Header, Sill and Threashold

About 6 years ago we had a moisture ant problem near our back door, they are since gone but our problem keeps getting worse. Our back deck may not have a correct flashing near our back door. We are in Northwest Washington and get tons of rain and this caused wet wood and the friendly and hungry moisture ants made our old house their home. Our back door has an aluminum threashold and under it all the wood is rotten, including the sill and the tops of the floor joist headers, the lower area of the door jam is also rotten. It is so bad that an walking out the door is nearly unsafe, the floor near the door on the inside of the house has so much spring and flex when standing, it nearly feels as if one day I will fall into the crawl space below. Our house is only about 15 years old, and this problem desperatly needs repair. I am not by any means a contractor, but really would like to tackle the problem my self. Can anyone provide instruction (with photos or drawings) of how to fix this problem. My main concerns are when I start to remove the threashold how do I fix the sill under the door and walls to the left and right of the door and the joist headers (will I have to jack up the house?) and the floor where it is rotten, and we have vinyl linoleum, will all this need replaced? Also would the door jam need replaced entirely or just the bottom where it is rotten replaced? I can provide photos if I can figure out how to post them. Thanks to all ahead of time.

Re: Moisture Ants Rotten Joist Header, Sill and Threshold

Its not really the easiest of do it yourself projects especially if you don't have a lot of experience. I'm not a contractor but have a good deal of experience with rehabbing a house. (I jacked up my entire house, replaced the entire first floor structure. Then cut the second floor off and jacked it up to give more head room. Will post pics when the whole thing is done).

But back to your dilemma. First I would remove the door and jamb. Its likely that if your door jamb is rotted the studs next to it are most likely rotted too. You have to really see how far the damage goes as carpenter ants can really do some major damage. You will also need to jack up part of the house to replace the sill and rim joist that is rotted. You will need to build a beam in the basement that spans well past where the roted area is and use jacks to jack up the floor (which should in turn jack up the walls and roof. DO NOT rely on the jacks to hold things up while working. Now you can remove the sill and rim joist back to a point where they are not rotted and replace. Use PT for the sill.

You shouldn't have to replace the joists just clean them up and I would recommend sistering on a new joist that spans the full length. (Some might say that you can just sister on a small section if there isn't to much rot but it won't add as much strength as a full joist. once you have the floor structure fixed you can let the house down.

Now you need to see if the studs and sill plates are rotted. If they are you will need to cut away drywall and jack up the roof and or second floor using the same method for the first floor. (note you just want to jack it up enough to take the weight off. If you go to much you will damage more drywall or plaster and possibly do other damage say to windows that are above). Replace anything that is rotted including the sub-floor.

As far as fixing the door jamb it is possible but it may not be worth the time and effort. You can get a better more energy efficient door most likely. You will also likely need to replace at least some of the vinyl flooring.

This is the way I would do it and as you can see it is not easy and is somewhat dangerous (don't put your fingers anywhere near where they could be crushed (and no that didn't happen to me but I can picture it in my mind)) and a lot of work is involved. Perhaps someone else has a different take on the situation and has an easier solution. At least if you decide to hire someone you know what might be involved. Hope this helps you out.


Re: Moisture Ants Rotten Joist Header, Sill and Threashold

There is also the idea to look for the source of the water infiltration which sounds like it may be coming in from the top of the door.

Re: Moisture Ants Rotten Joist Header, Sill and Threashold

Mike, Sure sounds much more intense that I had imagined. Thanks for the great input.

I think I will try and investigate just how rotten things are before I get too carried away. For starters, here are some photos of the threashold.

As you can see our deck is right at the door, the threashold sits right on the deck board butted up against the house, there is no flashing and here is where I think our big problem with water lies. The wind and rain beats against this outside of the door and soaks the wood under the threashold. The photos show were I removed the threashold board and underneath the subfloor particle board is toast, so much that I can shove a fork into it, I can push the fork all the way through to the crawl space below, it is as if there is no sill under it. I did get in the crawl space and could not tell without removing all the insulation in the area, so that will be my next task to get a better view of what is happening to the joists and sill. Standing about 18 inches away from the door, it the interior floor seems pretty firm. However when standing 6-8 inches away from the door the floor is really weak and bouncy, my wife thinks I will end up in the crawl space soon. So it doesn't sound like a very simple a fix, much bigger than by the sounds of it!

Re: Moisture Ants Rotten Joist Header, Sill and Threashold

Mahogan it appears you are correct that the deck was installed without proper flashing. The work necessary may be just at the door but I'm afraid it could require the removal of the deck and a more extensive repair. The rim joist and sill may be damaged the full length of the deck. Although this is a project a competent DIYer may be able to take on, you may want to consider having it inspected by a pro.

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