Moisture problem along the sill plate


  #1  
Old 04-30-09, 01:40 PM
K
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Moisture problem along the sill plate

Hello,

I've just opened up some drywall in my first floor living room for repair. I am surprised to find the sill plate is quite damp when it rains. There is no basement or crawl space in my house. There is no floor framing in the first floor. The sill plate sits just behind the baseboard on top of the concrete slab. That explains why the color of the carpet is always a little darker along the baseboard of the exterior wall. The sill is pressure treated. It's still in good condition. I don't see any sealer between the sill and the concrete. May be that's why the room is drafty in the winter. I have vinyl siding outside and it's in good shape. However, the siding stops when it meets the foundation. Is this right? I thought the siding should cover the first inch or so of the foundation. Also, the sill isn't positioned flush to the outside edge of the foundation. In some area, the sill plate overhangs from the foundation. Although it is covered by the siding on the side, I can feel the bottom of the wood with my hand from beneath. How can I cover it up? Also, how can I seal the gap between the sill and the foundation to stop the air infiltration?

Thanks,

Keith
 
  #2  
Old 04-30-09, 10:13 PM
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The siding should be proud of the sill by 1-1/2". Seal gap with backer rod (In weatherstripping asile), then caulking. Add window sticky wrap for a really good job. Remove the siding , 1st double or triple course with a zip tool. Google it. Be safe, G
 
  #3  
Old 05-01-09, 04:14 AM
B
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Hi Keith, GBR's explaination isn't exactly clear for me, so if you need more detail, just ask, he's one of the good guys.

If proud means to overlap the sill plate, how do you add that to this existing house?

Also, do you have gutters and how high is your siding off of the ground? You need to be certain where the water is coming from, splashing off the ground or shrubs, or leaking around windows/doors.

Bud
 
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Old 05-01-09, 02:40 PM
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First of all, thank you for helping me out...

I have already removed all the fiberglass insulation on the exterior wall and the wood frame is exposed to the inside of the house. Based on the water mark, I'm sure the moisture is coming somewhere from the bottom of the sill. I think the window is good. The end of the siding is a good 6 inches off the ground and the ground is clear. There is no gutter nearby. I think when the rain is sliding down the siding, the surface tension forces the water to sweep underneath at the end and wet the bottom of the sill that is overhanged from the foundation.

With the siding level with the sill plate, how can I stick a backer rod on the bottom of the overhanging sill? There is no gap there. The siding is flush with the bottom of the sill. If I need to overlap the siding to the sill for additional 1-1/2", how can I add that to the existing siding?

Thanks,

Keith
 
  #5  
Old 05-01-09, 03:44 PM
B
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Hi again, I'm not terribly experienced with vinyl siding, but the jobs I have done started with a starter strip that allows the first course of siding to snap on. That strip might allow uou to slide a piece of flashing in behind the starter and extend down below the siding. You could use the trim that is uded on houses as it comes in colors that might match your siding and look reasonable. If you find a trim guy, they could bend up some for you to kick it out away from the foundation. A bead of caulking behind it and your are all set. You could pick up some regular flashing and try an area before you do the whole house.

Bud
 
  #6  
Old 05-01-09, 03:51 PM
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Ok. " Also, how can I seal the gap between the sill and the foundation to stop the air infiltration?" Caulk between foundation and plate. Bigger gaps (1/4+) install backer rod, then caulking.

Does the bottom horizontal siding piece have a formed bead 1/2" up on the bottom back edge? Either use another sililar or contrasting color piece of new siding, attach it to the bottom piece. (May have to rip it)

OR use a trim vinyl piece horizontally there, to create a belly band effect.

Anything to keep the water from wicking up or pressure forced up into house.

Another option is to install 10' ovelapping pieces of z- flashing, upside down, under the siding bottom. Install the flashing under and behind the siding bottom,against the sill and sheathing, Pull the flashing down so the z- part touches the siding, with the flat part covering the sill. Install with stainless steel screws, caulk the heads.

Be safe, G
 
  #7  
Old 05-01-09, 03:58 PM
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They say great minds........... LOL! Ok, Bud, I'm thinking of a number between......

Be safe, G
 
  #8  
Old 05-01-09, 04:33 PM
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Seven but I have to use 25 words.

Bud
 
  #9  
Old 05-02-09, 11:13 AM
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Thanks again Bud & GBR. I will stop by the big box store to see what kind of siding trim and flashing is available. -- Keith
 
 

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