# Wood Under Door Sill is Rotted



## rgmetro (Apr 9, 2007)

So we have the exterminator come to treat for carpenter ants...

i had just installed a thermatru pre hung door about a year and a half ago...while cleaning up some dead ants, i notice my wood moulding on the bottom of the door was loose...pulled it off and discovered the entire bottom wood was wet/moist/eaten. i just pulled it all out with a large screw driver (it crumbled) and i'm going to let it air dry for a bit as its suppose to be nice out for the next 4 or 5 days here.

as there's no support from beneath right now, i shimmed a piece of wood underneath for support til i figure out what to do.

i'd rather not remove the entire door as it looks like the problem is confined to underneath the door. the house is on a slab. 

so i guess my questions are:

can i insert cut 6" wide pieces of PT wood underneath with space between them and shimmy them tight underneath. Can i use that plastic composite wood instead?

and my next problem is figuring out where the water came from. the only place i can think of is the aluminum sill has an extender on it. there's a joining seam that i would guess water would penetrate into and down into the wood. if i place a bead of silicon there i would think that would do the trick.

any help or advice would be appreciated


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## Ron6519 (Mar 28, 2007)

It sounds like the door wasn't installed correctly. There should be a membrane flashing under the door and on top of the wood base and up the R.O. frame sides. The aluminum sill should have been silicone caulked to prevent water infiltration from getting under the door.
Take the door out and install it correctly would be my advice. You can do it correctly or you can do it again, and again, and...
Ron


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## rgmetro (Apr 9, 2007)

talked to the people at thermatru...

i won't need to take the door out. the sill extender needs to be removed....and i'm going to need to run a bead of caulk along the intitial sill...reinsert the extender and bead that as well.

i installed the door myself...and put a rubber membrane along the top...overlapping those on the sides. i never put one on the bottom cause their sill was suppose to do that...

anyway, i'm going to replace the wood underneath in intervals and check up on it in a few months to see if there's any moisture.

i guess i'm just lucky my house is on a slab.


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## WNYcarpenter (Jun 19, 2007)

Carpenter ants thrive in damp wood environments. If I understand the situation, your rim joist, and subfloor are gone. That doesn't happen normally in 1 1/2 years. If you don't remove the door and address the situation you're headed for more trouble. You can chissel out rotten material and scab in PT but that's a bandaid curing cancer.

Either existing damage was overlooked when the original installation took place, or the door was installed without proper flashing. Therma-tru puts out a good product, the problem lies in the water preventative details not the engineering of the door.


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## rgmetro (Apr 9, 2007)

subfloor is concrete...so its fine.

the door itself is fine...the wood underneath the sill is fine...just the wood that the door sat on is gone...it was damp, infested and crumbled...so i removed it all and placed temporary support there until i put some PT wood or composite wood there with cedar shims.

like i mentioned, i called thermatru and they asked if the sill was caulked where the sill extender connects to the main sill...it wasn't. water seeped in from there and entered the front of the wood there...this is where it was the wettest when i pulled it out...so it makes sense...

my problem now is removing the aluminum sill extension...its 1" wide and is sitting underneath the side jambs so i can't just flip it up and off. i'm going to need to cut it i think

would a dremel be able to handle this? i'm trying to do as little damage to the existing components of the door.


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## rgmetro (Apr 9, 2007)

btw..i'd love to email someone a pic of the sill that i took to see they're take.

if you can pm me and i will...thanks...


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## rgmetro (Apr 9, 2007)




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## rgmetro (Apr 9, 2007)

the pic is above...it seems the water seeps through that seam..and make it way below to the wood below....

i have to pull out the narrow sill in front...caulk underneath the main sill, put the narrow sill back...caulk again where its already caulked now.


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## Ron6519 (Mar 28, 2007)

There's no way to remove it in place without ruining the ball/socket connection. It slides in from the side so the two sills connect and then the sills are screwed in from the side, through the frame. If you take out the door you can disassemble the sill and put down the membrane as a back up to the caulk.
Ron


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## rgmetro (Apr 9, 2007)

the people at thermatru told me i could pivot it up...and then pull it out.

but the problem is it extends underneath the sides (jambs).

if i just place a bead on top of the seam, would that work?


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## WNYcarpenter (Jun 19, 2007)

rgmetro said:


> the pic is above...it seems the water seeps through that seam..and make it way below to the wood below....
> 
> i have to pull out the narrow sill in front...caulk underneath the main sill, put the narrow sill back...caulk again where its already caulked now.


 Your picture explains a lot, not at all what I envisioned!


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## rgmetro (Apr 9, 2007)

if anyone is curious/interested....i figured out the problem.

the sill is bowed just a little (have no idea why) in the center...so water is running towards the sides...where i never caulked on the inside...behind the door edge. water would slowly run down there and ruin the wood below.

i saw this when i was staring at the door while loading the kids to go to the beach..(the bow)....

i put a nice bead of silicone on the edges (inside) and that should solve the problem. the connection between the 2 sills is not a problem. i spoke to a guy at the lumberyard (who sells thermatru) and he said, while its possible, the connection is designed to prevent this.

thanks for everyones input. and once again, caulk is a handyman's best friend.:laughing:


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## NJoytheRide (Nov 10, 2010)

*I have almost the same problem*

I need some help and advice on the same thing, but I am a new DIY guy. I have a rotted wood "riser" underneath of an aluminum threshold/sillplate that is moist and soft. 

Background: I found this because inside my back door was a slightly below grade sheetrock wall with visible mildew and spongeyness to the touch. Within the past six months of new home ownership, the wall has leaked water only twice with a trail of water coming from out of the moulding at the floor. I pulled out the sheetrock and found 4 layers of half inch sheetrock, all mildew ridden, and above that an old decorative wood panel that was wet and has been eaten by some insect. I pulled out this panel and realized it extends right next to this door "riser", so the water is probably coming in from this piece of wood. 

The Riser is still wet, 2-3 days after it rained, and it almost comes all the way out with a crowbar, but won't. It seems to be attached to the aluminum sill plate.

My questions: How do I get the aluminum sill plate out to get a better look at the "riser"? Do I need to remove the aluminum-covered wood casing around the door?(the riser seems to be attached to it somehow)

I have tried looking all over the web for videos or text instructions for both how to remove this type of threshold, AND how to install one, (thinking I could just reverse the steps to remove it) with NO LUCK.

Please help. Winter is fast approaching and I need to get this done before the snow and slush come.

When I get home tonight, I will take and post some photos, because that seemed to help readers of the original post here.


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## NJoytheRide (Nov 10, 2010)

Inside of house, the small wall on lower right was moldy, and leaking water from baseboard moulding.









Outside of door with rotted wood "riser" under aluminum threshold/sill plate.









Above is a picture of the wood "riser" being pulled out about 2 inches from the house by a crowbar. as you can see, there is a aluminum casing cover above the crowbar. Do I need to remove that first?

ok, again, how do I get the


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## fixit4u (Nov 14, 2010)

rgmetro said:


> So we have the exterminator come to treat for carpenter ants...
> 
> i had just installed a thermatru pre hung door about a year and a half ago...while cleaning up some dead ants, i notice my wood moulding on the bottom of the door was loose...pulled it off and discovered the entire bottom wood was wet/moist/eaten. i just pulled it all out with a large screw driver (it crumbled) and i'm going to let it air dry for a bit as its suppose to be nice out for the next 4 or 5 days here.
> 
> ...


There are some easy ways to fix rotted wood explained here that may save you a lot of work
how to repair rotted wood


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