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Community and Q&A

Ice and Water Shield on Walls?

Stephen Edge | Posted in General Questions on

I live in northen NH. My home has a stepped foundation which puts some of it within 2-4 inches from the ground on the eve side. It has a steel roof and no gutters so rain splash soaks the walls. My builder put I&W on the first three feet of the walls to combat the soaking that can happen from snow build up and splashing against the vinyl siding. If I make sure I allow drying to the inside of the walk in basement, and keep humidity in check, will I be ok? Or am I asking for rot from dew point? I can’t see how it could rot with not much air between the I&W and the outside sheathing… Foamboad on the outside is not an option which is too bad.. I do have 2in on the gables.

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Replies

  1. GBA Editor
    Martin Holladay | | #1

    Stephen,
    The best solution to your problem is to lower the grade, if possible. Ideally, the grade should be at least 8 inches (12 inches is better) below the lowest wood components of the house.

    Whether or not the Ice & Water Shield will cause problems depends entirely on the wall construction details of your house. If your house has lots of exterior rigid foam insulation, the Ice & Water Shield will do no harm. It doesn't sound like that's the case with your house, however.

    If you have conventional 2x4 or 2x6 wall framing, and OSB sheathing, and fluffy stuff insulating the stud bays ... well, let's just say that installing Ice & Water Shield on the outside of your wall is a very bad idea. Once your OSB gets wet -- something that typically happens every winter -- it will dry slowly, if at all. In the long run, you may end up with mold or rot.

  2. Daniel McCauley | | #2

    A builder friend once put I&W under a stucco job. 2x6 walls, standard fiberglass fill. It had mold growing before the place was even finished, drywall was up and taped but no paint yet. This in the mid-Atlantic and not even into winter yet. Granted he did cover the entire surface, but it was enough to scare me away from that technique for good.

  3. John Brooks | | #4

    Interesting point Stephen.....
    I think that Martin's warning is wise ..
    and the detail in the 10 year old Taunton article is not-so-good

  4. Glen M | | #5

    Stephen,

    Martin's points are valid, however the situation you have seems to be fairly common. I re-modeled by parents home (Albany NY area), and on the north side of the house, the sheathing had moisture damage (not terrible, but needed some replacement) from snow build-up over the years and it was about 8-12" above grade. As you know, you may get 12"+ up against the house for an extend period. The original installer, put (2) layers of felt, which at the time (30 years ago) was probably the standard practice. We put ice/water shield back at this location only, but it was at a ventilated crawl space with no insulation, so the possibility of dew point/moisture issues is small since the wall temperatures are likely to be very similar.

    Do you know if the builder put in a vapor retarder/barrier behind the drywall? If so, that is definitely a problem since the wall cannot breath in either direction.

    As Martin noted, the insulation is probably the biggest issue with the assembly. If you used closed-cell foam you likely eliminated the potential problem and you no longer have to worry about humidity, temperature, etc. If batts, blown-in, etc were used, replacing it may not be a realistic option at this point.

    I do wonder if you keep the basement fairly dry (dryer than outside, which is tough in winter) you may not have a problem since the majority of the wall does not have the i/w so wouldn't it dry out to the other areas? It may be a slower pace., but the entire wall is not sealed. The peel and stick is commonly used, but don't see major concerns with it, although a 6-inch wide strip only around openings is not the same as a 36" wide roll. You may also have to run the dehumidifier more to keep this atmosphere condition.

    I would like to hear solutions to this since even at 12", you will get snow against the house so what is the solution to protect the sheathing? You used vinyl which doesn't absorb any moisture, but fiber cement does, which would then wet the sheathing and potentially the insulation.

  5. Stephen Edge | | #6

    Glen, Lucky for my north wall, I have 2inches of external foam. My east wall "had" the ice and water I mentioned in my origional post until today. I cut most of it off my pressure treated plywood today but left a foot along the bottom for the constant splash and snow melt from my steel roof. I can not do external foam on this east wall so I replaced the I&W with felt and will now try to figure out what to insulate the interior wall with. 2in of foam board over 2x6 filled with wool or cellulose batts are where I'm leaning.. thoughts anyone? Thanks!

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