French door with bad threshold, moisture in sheetrock

Hello All,
We just bought a townhouse and found out about an issue I need help with.

There is a french door on the middle level, leading out to the deck. It is about 17 years old, and the threshold is rotten/wobbly on one side. In the finished basement directly below this door, the sheetrock registers 40% moisture when checked with a moisture tool. The 40% moisture area is directly below the wobbly threshold area.

There are some problems with the flashing/siding at the bottom of the door. From what I have read, the problem could be the threshold/door itself, the flashing at the top of the door, or the bottom.

We had this exact same problem in my last townhouse. We had to install a new french door, perform subfloor repair, etc. What a disaster!

Is there any way to tell what the root cause is? I'd really like to know if it is the flashing/siding, or just that the threshold is shot from age and leaking water down through the wall.

Thanks so much, I hate this issue and have already lived through it once.

Drew

I'll make a few guesses. The deck was built right up under the threshold, there is no sill pan under the door to prevent water from getting in, there is little or no support directly under the outside of the threshold.
That's the reason at least three times a year I get paid about $1000.00 to come out and fix french and slidding doors.
All of this could have been prevented for about $20.00 for a sill pan and building the deck at least 4" below the threshold.
If you key word search Jam Sill you can see what I'm talking about. Any real lumber yard will sell them. For some odd reason Home Depot and Lowes will not have a clue what your talking about and do not stock them.
If the jams are rotted now then the door is trash and needs to be replaced. But this time add the sill pan.

Thanks for the reply. I was planning to take pictures tonight but it got too dark.

I would assume you are right about all the construction mistakes.

Edit--I think the threshold is about 4" above the deck.

The thing that gives me heartburn is finding a contractor who actually KNOWS how to do it right.

I had an HVAC guy come out last week and tell me he couldn't order a safety switch for my furnace. I found one online for $30. He just wanted to sell me a new furnace.

If I end up having to buy a new french door set, and pay for installation, I just want to use someone who KNOWS how to set up the flashing properly (sill pan, etc.). Finding that contractor is really tough.

Thanks,
Drew

Go to your local lumber yard not (HD or Lowes) and ask the owner who he would use.
There also should have been 6" wide rubber window seal around the nailing flanges on that door.
I'm also in VA but today I'm in Keysville VA helping out a lady trying to fix up a house to sell because she also could not find anyone local she could trust.
I live in Hallieford 23068 and had to drive for 2 hours to get here.

Here are some pictures. Time to begin the quote process I guess :hide:

Here's what I see, the siding was installed wrong, I would have used a piece of vinyl lumber under that door the full width so it would have fully supported the threshold and would not have stuck out past the doors threshold.
As far as the door goes it's one of those cheap contrator grade wooden doors with wooden brick molding and a very cheap thin threshold .
Her's what needs to be done and what your facing.
The door needs to come completly out, all siding below and on the sides of the door needs to come out, flooring will need to be removed so the sub flooring can be looked at, what you then will find is the sub flooring is shot at least a foot behind that door, the sheathing will be rotted below the door and need to be replaced, if your lucky that's it but as poor as that was done I would not be surprized to also see the floor joist rotted and it may be even the bottom plate.
The way they installed that siding all they did was form a funnel for water to get in.
Once all the woods replaced I'd use a piece of Storm and Ice shield and run it so it folded over the threshold area and down the outside wall to cover the sheathing to the top of the deck. I'd then install a sill pan for the door to set on.
I'd replace the door with one made by Attrum (Home Depot sells them, but it's going to be a special order so order the door and recieve it before doing any repair work) with vinyl jams and vinyl brick moulding. Then I'd install a piece of vinyl lumber under that threshold that's wide enough to sit on the deck and come up tight to the bottom of the threshold, making sure it does not stick out past the threshold.
It will stop the threshold from twisting and cracking the caulking in the corners where the jams meet it.
The nailing fin on the door will need to have window tape on all sides.
Then you can reinstall the siding.
In most cases all this can be done in one day by someone that knows what there doing.
It will take two people because of the heavy door.

WOW! Thanks for all of the information.

So I should look for a door with Vinyl brick molding, that's a good thought.

I would do back flips if I could find a contractor who knows half of what you have posted on this thread. Everybody knows how to install a door, but I need someone who can do the whole job end-to-end.

Thanks again,

Drew

Here's something else I'd guess your deck and door opening is missing.
Video: Protecting Your Deck
One thing I did notice in this video there using alumiunum coil stock in direct contact with a pressure treated deck. It should have been vinyl or copper because of electrolisis. It even says so right on the coil stock box. This is what was suppost to be under that door to protect the subflooring and stop the water from taking out the wall below it.
http://www.jamsill.com/
For some strange reason Lowes and Home Depot do not even sell this product. It could save home owners thousands of dollar every year in home repair if it was code to install one everywhere.