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Vinyl siding on top of exterior mineral wool boards?

Debra_Ann | Posted in Energy Efficiency and Durability on

I’m building in climate zone 4a, and plan to have 6″ walls filled with mineral wool batts. I also plan to use plywood as exterior sheathing, to improve the drying out of the wall and reduce possible mold growth on the interior of the sheathing.

I’m trying to decide how helpful it may be to include exterior insulation in this climate to reduce winter moisture levels on the interior side of the exterior sheathing. I feel very strongly about building walls that can dry easily in both directions, so I’m not very interested in using exterior foam insulation.

But I haven’t been able to find out how feasible it is to install vinyl siding on mineral wool boards. What little I’ve found out says that:

1) Vinyl siding should not be installed on furring strips, but only directly on flat and smooth sheathing.
2) Also, that any exterior insulation should not exceed 1″ thick (which is thinner than most mineral wool boards)
3) And that the nails supporting the vinyl siding should be anchored 3/4″ deep directly in studs (not in 1/2″ sheathing).
4) Also, most brands of vinyl siding require nailing in studs every 16″, which wouldn’t work with 24″ spaced studs. (sigh…)

I don’t want to lose the warranty for vinyl siding by incorrect installation. Has anybody found a way to make this work with mineral wool? At this point, I’m tempted to just drop the idea of using exterior insulation at all. (I’m easily frustrated)

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  1. Jon_Harrod | | #1

    I do not think vinyl over mineral wool board is advisable. Because of the compressibility of the board, it's going to be very difficult to get the siding flat enough to look good.

  2. Expert Member

    I remember a thread on this subject. When Martin gets back from golfing at Mar-a-Lago he will no doubt be able to find it.

  3. GBA Editor
    Martin Holladay | | #3

    At first I was hesitant to cough up the annual $200,000 fee to golf at Mar-a-Lago, but now that I have taken the plunge, all I can say is -- "Wow. It's worth it. Let me tell you, it's the best golf course in the world. Fabulous. Beautiful. The best."

    Here is the link to the earlier Q&A thread: Roxul Comfortboard rainscreen.

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