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Community and Q&A

What to do about ice dams after open-cell foam has been installed?

Adrienne Raymond | Posted in Energy Efficiency and Durability on

Our school recently had a full roofing insulation project done with open-cell foam, in part to solve air leaks that have resulted in ice dams and leaks into the school proper.

We have seen a reduction in the amount of ice forming, but yesterday we had a full-scale leak in a room on the east side of our multipurpose room (gym). Now the foam appears soaked — we haven’t determined how much yet — and we are wondering what we have gotten ourselves into.

We expected the foam to solve the air leaks and prevent the ice dams and this was one of our worst leaks ever. What now?

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  1. GBA Editor
    Martin Holladay | | #1

    We need much more information to help you.

    1. What is your climate?

    2. What is the slope of your roof? Is the ice accumulating in a valley?

    3. What type of roofing do you have?

    4. Have you been on the roof? How thick is the ice? How deep is the snow? Has anyone tried to shovel the roof?

    5. Where was the spray foam installed: under sloping roof sheathing or on an attic floor?

    6. How thick is the spray foam?

    7. Is there a ventilation channel between the spray foam and the roof sheathing?

    8. Did your spray foam contractor make any promises concerning the performance of the foam in relation to your ice dam problem?

    9. Did your contractor come back to look at your roof and make recommendations?

  2. Adrienne Raymond | | #2

    1, central VT
    2. relatively shallow sloped roof- you can walk up easily, but if you slip you would roll off
    3. asphalt shingles
    4. snow is about 14 inches with maybe 2 inches of ice buildup over the eaves
    5. installed on sloping roof sheathing
    6. spec. for project was to achieve R-44 with 2" closed cell and 8" open cell- not sure what is there as this has been the icing on the cake for a project "with problems".
    7. no
    8. It was reference as one of the main reasons we were doing the project, but no.
    9. hopefully this morning- there have been problems with odors, too. This may be just another thing to add to the list......

  3. Adrienne Raymond | | #3

    I made a mistake....
    6. Spec. was "We will spray open cell foam at a thickness to install R-38 at the roof level. The gable ends will be insulated to an R-15. All foam will be sprayed with a fire retardant coating. The gym attic kneewalls will be treated with same system as above.

  4. Skylar Swinford | | #4

    Any photos?

  5. GBA Editor
    Martin Holladay | | #5

    It's impossible to assess what's going on without a site inspection, but here are some thoughts:

    1. In order to assess the effectiveness of the new insulation, the existing ice at the eaves of your building will have to be removed.

    2. To achieve R-38 with open-cell foam requires at least 10 inches of foam. The thickness of the installed foam should be verified.

    3. The residential code calls for roofs to be insulated to a minimum R-value of R-49 in climate zone 6 (Vermont). I'm not sure which code applies to schools, but someone should check to see if R-38 meets minimum code requirements.

    4. Open-cell foam is not a vapor barrier, so you should ask your contractor if he or she remembered to install a vapor retarder on the interior surface of the cured foam.

    5. Ask your contractor for a copy of the ICC-ES report to verify that the brand of open-cell foam that was installed can be installed to a thickness of 10 inches or more. Many foams have thickness limitations, so 10 inches might exceed the manufacturer's recommendations.

    6. You should verify with the fire marshall or Vermont Dept. of Labor and Industry that the "fire retardant coating" meets code requirements. Many building officials insist that exposed foam should be covered with a more substantial thermal barrier like drywall.

  6. Adrienne Raymond | | #6

    1 Are you referring to the interior or exterior ice buildup- the wet insulation has ice on it.
    2 I will check with the installer- he is coming up tomorrow morning.
    3 There are no local codes, but I will check to see if the State has any requirements- I don't believe so- I am the Zoning Admin. in our Town.
    4 He put on 2 coats of a Bayer product for vapor and fire retardantcy.
    5 I will ask
    6 I hate to check with the Marshall, but I'll do it in the morning.

    to poster 5- I'll try to get pictures in the morning. Thanks to you both. Adrienne

  7. GBA Editor
    Martin Holladay | | #7

    1. I was referring to the ice build up on the exterior, at the eaves of your roof. If that ice (presumably ice which built up before the new insulation was installed) isn't removed, it could contribute to a new leak which isn't entirely the fault of your new insulation.

    2. I'm suggesting that you don't take your installer's word for it -- I'm suggesting that a school employee or an employee from the superintendent's office (or perhaps a school board member) should verify the thickness of the insulation that was installed.

    3. The Vermont Department of Labor and Industry should be able to explain which codes apply to school construction in Vermont.

    4. As long as the fire retardant is also a vapor retarder, you should be OK on that point.

    5. Hopefully your contractor will have no problem submitting the ICC-ES report showing maximum thickness restrictions.

    6. My advice to school boards is always, "Don't be afraid to contact code officials -- you want your school to be in full compliance with all codes." You certainly don't want any code violation that (heaven forbid) results in a tragic death in the future.

  8. Michael Chandler | | #8

    I see a red flag on "We will spray open cell foam at a thickness to install R-38 at the roof level. The gable ends will be insulated to an R-15."

    I'd get a broom handle with a wire landscape flag taped to the end of it sticking out 10 1/2" which is what it would take to achieve R-38 with open cell foam at R-3.6 / inch. if the flag hits the roof before the end of the broom stick hits the foam you don't have the thickness your contract called for. Many of these guys use, and believe in, "virtual R-value" and would consider 5 or 6 inches to be "R-38 equivalent" take some measurements ans see if you really have what you paid for.

    If you are losing heat so quickly that you have ice dams and the resulting leaks are freezing on the warm side of the foam it would seem likely that you don't have 10 1/2" up there. I agree with Martin that the foam should be separated from the living space with painted drywall rather than intumescent paint.

  9. GBA Editor
    Martin Holladay | | #9

    Michael's advice is good, although I would probably use a straightened coat hanger rather than a broom handle.

  10. Adrienne Raymond | | #10

    I will measure the foam as suggested. The ice build up is all in the last few weeks the insulation was installed the beginning of Dec. Our other issue is an ongoing odor, but that will be another post. All in all this has not been a positive experience so far.

  11. Expert Member
    Michael Maines | | #11

    Adrienne, an ongoing odor is significant, as it might indicate improperly mixed foam.

    Open cell foam that is saturated will not insulate, so it does not seem surprising that you would have interior ice after the recent cold spell.

  12. Adrienne Raymond | | #12

    The wet foam is being removed and the air leak are being looked for. The question about the foam odor is our biggest issue. Once foam has been improperly mixed or what ever has kept it from a proper cure, does the odor ever leave? Or is the only option tearing out the bad foam?

  13. Michael Chandler | | #13

    Martin the broom handle is intended to hold the landscape wire flag and could just as easily hold a straightened coat hanger but the wire flag is thinner and stiffer because the steel is harder.

    The idea is that you extend the wire beyond the end of the coat hanger by the depth specified in the contract and if the end of the wire penetrates to the roof sheathing before the end of the broom handle touches the fact of the foam then the foam is too thin.

    Did you think I was advising that she probe the foam with a broom handle?

    If the odor is "fishy" then it may be the amine catalyst (too much humidity on day of spraying?) I don't know of a good way to use up the balance of the catalyst, perhaps the supplier will have a solution.

  14. Paul Eldrenkamp | | #14

    This problem sounds like it has the potential to grow completely out of control; it does not seem like the sort of situation that can be dealt with on an on-line forum. I think Adrienne needs to bring in someone qualified to do some fairly sophisticated diagnostics. Adrienne: Is funding available to hire (for instance) Building Science Corp?

  15. GBA Editor
    Martin Holladay | | #15

    I get it now -- your explanation makes sense.
    (Duh.) I thought you were advising inserting the broom handle into the foam.

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