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Redwood siding corrodes building paper?

2eHPEwE64w | Posted in GBA Pro Help on

I recently moved into a redwood-sided house built ca. 1992 in climate area 5A (midwest). I have have problems with leaking roofs – i thought – until the roofer took off some of the siding below an area where two parts of the house come together – to find that the building paper was corroded, the sheathing completely rotten, and studs and sill plate partially rotten too. Joseph Lstiburek wrote an article in Fine Homebuilding (2001) about “surfactants” present in the tannin of cedar and redwood, which i found when desperately searching the web for solutions to the problem of my house rotting from the inside out (I have since noticed that a lot of cracking is occurring in several places, that could point to massive rot). It really seems like the rain just comes right in, and that whatever type of building paper (what would it have been in 1992?) is there, is now completely ineffectual.
What type of building wrap can be used with redwood, assuming i now have to have all the siding taken off?

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  1. GBA Editor
    Martin Holladay | | #1

    While it's true that surfactants in redwood can cause the deterioration of plastic housewrap or (in some cases) asphalt felt, the sheathing rot at your house is unusual and indicates that something else is going on.

    The first step is to discover the source of the moisture that cause the sheathing rot. Possible sources include:
    1. A roof leak that runs down your wall.
    2. Large amounts of water hitting your siding due to an unusual situation (a valley that dumps water on a wall, no overhangs, etc.)
    3. Very high indoor humidity.

    We can't diagnose this over the internet. You'll need to do some detective work, or hire someone who can help you do that detective work.

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