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I have a home built in the late 1960s in Massachusetts. The prior owner covered the house with vinyl, which was not done with care. Water gets behind the vinyl. The cedar wood clapboard and trim is rotted in some places. Also, behind the cedar is missing and or torn tar paper. There is a heavy mildew smell outside in places. Inside there is a dry musty smell as well sometimes mostly on hot days. To fix these problems, we are considering removing the vinyl and replacing the siding with new cedar wood along with putting in a rainscreen. However, my main concern is that everyone wants to wrap the house airtight. I am concerned that wrapping the house airtight will prevent the house from breathing and trap dry musty and mildew smells inside the house more so than it already does. If I put in a rainscreen, however, it seems that I should wrap the house with something. My house does not have central air, which makes an air exchange less practical as an alternative solution.

What do you recommend for my house?

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The house wraps are vapor barriers that breathe. They are much better than the old tarpaper for keeping moisture out.

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It may be that rot extends all the way to and into the sheathing. This is a set of planks (1/2" or 3/4" thick) nailed directly to the studs. Horizontal lapped courses of black felt (tar paper) were nailed over the sheathing and the siding clapboards nailed over that. (In later construction plywood was used for sheathing and in still later OSB.)

It sounds like the vinyl siding was placed on top of and nailed into the old clapboards. You will probably have to remove all layers down to the sheathing and examine the sheathing for rot. If you have to replace some of the sheathing, then someone here can tell you how to handle that.

Once you repair/replace sheathing, you nail Tyvek house wrap to the sheathing, then nail clapboards or sheet siding into the sheathing. My preference is for stainless steel ring shank siding nails, hand nailed.

If you want a rainscreen wall, you will nail vertical battens to the sheathing (housewrap between sheathing and battens) and nail siding through the battens and into the sheathing and even into the studs. You would probably want to use pressure treated battens to resist rot. There are some plastic batten systems specifically for rainscreen walls. IIRC at one time Tyvek made a thickly furrowed housewrap that was designed to allow water to drain down behind the siding.

A rainscreen wall has a gap of 3/8" or 1/2" between the back side of the siding and the sheathing/housewrap. At the bottom and the top of the siding there must be screening to keep insects from harboring in this space while allowing water to drain unimpeded and air to flow through.

It seems to me that a rainscreen wall requires much more attention to detail in design and construction than just nailing siding to sheathing and studs. Unless you really need it, it might not be worth the trouble and expense.

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  • Thank you! The entire house has vinyl siding, but the back wall of the house is the area with the rot. From your experience, would it be difficult to take the vinyl off the back wall, fix the rot with new cedar (and rainscreen), and leave the wood exposed, but also leave the rest of the vinyl on the rest of the house? This would make the project more manageable & less expensive, but I would not want to do anything that would cause more problems down the road. I think this could be properly flashed, but I am not sure what problems I might have at the corners where the vinyl & wood siding meet.
    – ML123
    Sep 8 '20 at 16:43
  • What are the dimensions of that end of the house? Are there windows in it? A rainscreen wall is perhaps not ideal as a first project for a new DIYer. But if you read up on installing siding, it is possible. Is hiring a competent carpenter a budget buster? An incompetent or dishonest contractor is a nightmare possibly leaving you with a "mechanic's lien" on the property. I can understand your attraction for cedar siding. Are you planning to paint it or stain it? Sep 9 '20 at 0:09

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