Several square feet of plywood sheathing, which sits underneath my home's aluminum siding, shows signs of rot. It's visible from inside my attic, and therefore "accessible" in a sense, except that the wall studs are in the way, every 16 inches. The sheathing is not terribly rotted, ie not crumbling out entirely, and no visible problems from the outside of house. What can I do to replace the sheathing without removing a lot of siding? Or should I consider using a chemical or epoxy wood filler type product? I don't see any active leak in this area when it rains, but it must have leaked in the past, I imagine.

 

Since you can see it in the attic it is probably on the gable end. You would not have to remove a large amount of siding to repair it. I would not know how to tell you to replace it from inside and would not do it that way.

 

The only way to replace it is from the outside. Take off whatever siding you need to in order to do it right.

 

Thanks, guys, it is indeed on the gable end. Not sure but some of it may be hidden behind a brick chimney! In that case i imagine so "interior attack" is necessary but I haven't a clue as to how to do it!

 

If it is behind, or adjacent to a chimney or chase, it probably isn't coming in from the siding, but from the joint where the siding meets either the chase or the brick on the chimney. A possible cause of this is improper flashing between the chimney and the siding. Still an outside attack. Is the area still wet, or is it just showing signs of previous moisture damage. If it is dry, keep an eye on it and check it after a rain storm to see if you can detect current leakage before you go tearing into it. Keep us posted.

 

And if the chimney goes through the roof, there could be leakage where the shingles meet the chimney- the step flashing and/or counterflashing.

 

Chimney doesn't penetrate roof; it lies against gable end of house. My wife had a contractor look at it a couple of weeks ago; unfortunately I couldn't attend. Here's what he wrote:

"Sister in new 2 x 6 roof rafter to support rotted one. Remove 4 studs so we can remove the rotted 1/2" sheathing. Replace studs w/ new 2 x 4 and dispose of debris. Price: $1,200."

That's got to be an "interior attack", else why would he be removing studwork? But if that approach is used, how can the rotted sheathing be removed w/o removing the alum siding? I assume there's some type of clips or nailing to hold the siding to the sheathing??

The area is dry now, but when I pulled out some rot I could see a little daylight, obviously that needs adressing. I'll pop up during the next rainstorm and check it. Thanks again.

 

If the damage is behind the chimney, there is no siding and could very well be attacked from inside the attic.

 

Thank you. That's what I'm doing and the cost will be a lot less than $1,200!!