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New siding over two existing layers

Chris Maida | Posted in General Questions on

I’m looking to install new vinyl siding. The house was built in the late 40’s and has currently has two layers of siding on it. The top layer is cedar board and batten. The second layer is clapboard, but I’m not sure of the material type.

I’ve met with three contractors. One wants to remove both layers while the other two were planning to side over both of the existing layers removing only the batten. The last contractor went back and forth before deciding that siding over both layers would be ok.

It seems to be common practice to side over an existing layer over siding. However I can’t seem to find any information about installing a third layer of siding.

Am I asking for trouble by installing a third layer of siding vs. removing one or both layers of the existing siding?

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Replies

  1. GBA Editor
    Martin Holladay | | #1

    Chris,
    I don't think there are any building-science reasons why the existing siding layers have to be removed. The main questions are:

    1. Are the underlying layers of siding sound, without any rot or soft spots? Are they well fastened? If so, you can install more siding over them if you want.

    2. Do you object to the fact that each successive layer of siding thickens your wall, creating trim problems at doors and windows? Eventually, your windows and doors will get a sunken appearance, considered unattractive by most observers.

    If it were my house, I would strip the existing siding down the the sheathing. That would allow the sheathing to be inspected for problems. It would also make it easier to install a water-resistant barrier (WRB) and proper flashing. It might also allow you to install a layer of rigid foam between the sheathing and the new siding.

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