In my neighborhood a guy is renovating his house and adding a floor to his bungalow. To my surprise this week all his walls are covered in some white sheets of something that seems to be insulation

Is this possible ? To add layers of insulation on top of something like brick? (these are old houses, built into the 60s with a layer of brick outside, an air gap inside and then plywood and drywall (at least this I can remember, also there is probably some sheet that would prevent vapor or humidity circulation)

  • is there anything printed on the white sheets?
    – jsotola
    Commented Apr 10, 2018 at 4:47
  • I don't remember seeing anything but I will look again today
    – MiniMe
    Commented Apr 10, 2018 at 13:54
  • Ok I checked today there is nothing printed on those white sheets..they look more like drywall from distance...can it be drywall?
    – MiniMe
    Commented Apr 11, 2018 at 3:18

2 Answers 2


Problem #1: When installing insulation, you should think “envelop”. That is to say, just applying slabs of insulation to exterior walls does not “help” the energy conservation of the building, if there are gaps between the slabs, around the edges, etc. there will be NO insulation qualities.

Problem #2: Moisture Barrier. I’m sure there is an existing moisture barrier. (Note: moisture barrier is different than vapor barrier. Let’s discuss moisture barrier first.) Moisture barriers are installed to keep OUTSIDE moisture from penetrating the exterior walls and causing dryrot, mold, etc. When you add another exterior layer, like insulation, it requires another moisture barrier. If moisture gets past this new moisture barrier it can get trapped and create dryrot, mold, etc.

Problem #3: Vapor barrier and Dew Point. Vapor barriers keep vapor from exiting the living spaces and getting into the insulation. Once in the insulation it can change into moisture through a process called “Reaching it’s Dew Point.” The placement of vapor barriers is important because vapor can change into moisture at the Dew Point and create dryrot, mold, etc. in the walls and ceilings. When there are two moisture barriers, this will often occur between them, depending on the amount of existing insulation in the wall.

Dryvit is a manufacturing company that has a system of installing insulation on the exterior of walls and then troweling on a coat of waterproof plaster. If you google it, you’ll see about a hundred lawsuits for these identical problems.

Be careful adding new “systems “ over existing systems.

  • Thank you Lee, could you please point me to a picture that shows what that plaster looks like and the before and after insulation ?
    – MiniMe
    Commented May 21, 2018 at 2:42

Years ago commercial buildings could be insulated with white styrofoam boards referred to as bead board. In my area the common term I heard used was "dryvit". The board was installed on the outside of a brick or stone building which was then covered with a "chicken wire " mesh and coated with a cement type covering. I "GOOGLED" the term and found out that it is still being used.

  • Thanks @d.george but my focus is not on the product but on the posibility to do it (pros cos and construction code requirements )
    – MiniMe
    Commented Apr 10, 2018 at 13:56
  • Can not help with the application of the product since I never used the product myself. I saw contractors installing the product on schools that were trying to be more energy efficient. The only draw back at that time was that the finished product could not resist being destroyed by kids with bricks, bats and balls and the like. As for code requirements, you will have to contact the "code enforcement officer" in your area.
    – d.george
    Commented Apr 10, 2018 at 18:09

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