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Ending ice dams and resultant water damage

Jake Swenson | Posted in Energy Efficiency and Durability on

Looking for recommended actions to address significant ice dams and water infiltration we experienced in our house this winter. I do not want to go through what we experienced this winter in terms of water damage again. Thanks in advance for your suggestions.

BACKGROUND: We live in a 2-story 1964-built colonial in eastern MA. We purchased the house in 2005. It is baseboard hot water oil heated, no A/C with backyard facing almost due south. We keep house at 66 in winter, 60 at night and during the day when we are away (5 days a week work hours). We have a walk up attic with fairly high ceilings on one end accessible from one of bedrooms upstairs.

We air-sealed and insulated attic in fall 2005 via Mass Save program incentives and Conservation Services Group. They air-sealed throughout and blew in cellulose insulation over existing fiberglass batting. However, we only have roof vent and a gable end vent in the attic, no soffit venting at all, which I was told at inspection should be done but we haven’t had that done yet.

We also have 10 recessed lights in second floor that were there when we bought house and have merely been wrapped in fiberglass when attic was insulated, which seems totally useless. We have gutters on main roof areas with leaf relief gutter covers on them that were installed 2 years ago.

Last winter we had icicles and ice dams and icicles coming out of our siding on south facing side of house as well as some water dripping through a newly renovated kitchen window wall as well as icicles and ice dams on north-facing side of house. Due to a tree destroying part of our house in Feb 2010, we installed a new roof in summer 2010. This winter despite new roof and hiring roof raking service to remove snow we were slammed. Major ceiling water damage in upstairs bedroom on north facing part of house, and downstairs in kitchen, dining room, family room, all south facing. Significant ice dams on both south and north sides of house. The ice and water shield that was used for new roof clearly did nothing. The G/C who did our roofing is claiming not his issue and it may not be, I have no idea.

QUESTIONS: It sounds from other research I’ve done online that we need to do the following. Appreciate feedback/suggestions:

1. Install continuous soffit venting – seems like a no-brainer, just do it.

2. Revisit all insulation in attic and find expert to do more advanced work on completely insulating and eliminating air infiltration to keep warm air out of attic and support a good “cold roof” system. I called an insulation specialist company in 2009 to review work done and they didn’t really suggest additional work in attic of any significance but they were highly rated by others. Can I trust an insulation specialist or should I be talking to someone who specializes in building envelopes and establishes strategy for insulation companies to execute on?

3. Related to #2 above, remove recessed lights or upgrade to completely insulatable version – maybe low heat emitting like LED? I’m willing to remove or replace recessed lights with fully insulated options if that works but hate to have to deal with the costs of all ceiling work.

4. Have someone inspect the roof and ensure that no gaps / issues in original installation and that ice and water shield is properly installed along edge of roof. Could a home inspector do this (we liked our original inspector a lot) or should I call another roofing contractor or some other specialist?

5. Consider removing gutters on some part or all of roof? I’ve heard gutters aren’t the issue with dams but have to wonder. Will this help at all, and what are the downsides of doing this as long as we landscape appropriately?

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  1. David Meiland | | #1

    It sounds like you have a decent grasp of this already. The attic is probably too warm due to insulation and air leakage issues. Blowing cellulose over fiberglass is apparently pretty common, but I don't know how the air sealing work can really be done without completely removing the fiberglass as the first step. I have had a few homeowners show me the door when I told them I would be tossing all the old insulation out so that I could completely clear the attic and get at every single air leak. Unfortunately, that's what you might need to do. The can lights are not helping either, and the IC/AT versions won't be much better. What's the access (stairs? hatch?) and what was done to seal that?

    As far as who to hire... my suggestion is to read up exhaustively on the issues, make yourself an expert, and then hire the person who immediately starts talking about the right solution. It might be an insulator, it might be a GC, it might be an energy auditor who has connections to contractors who know how to do the work.

  2. GBA Editor
    Martin Holladay | | #2

    It sounds like you are on the right track. A few thoughts:

    1. If your ceiling has 10 recessed can lights that "have merely been wrapped in fiberglass when attic was insulated," then it's not possible to say that the Conservation Services Group has air-sealed your attic. They didn't.

    2. The Conservation Services Group has a good reputation, so you should get on the phone and explain your situation, in hopes that someone there will take your call seriously and suggest some remedies.

    3. My guess is that the main flaw in your ceiling is air leakage. After you find a contractor to address you ceiling's air leaks, the next question is the R-value of your attic insulation. How deep is your insulation?

    4. Once you've had the air sealing done and verified that you have at least R-49 of attic insulation -- more is better -- you can consider installing soffit vents, although soffit vents are not a certain remedy, and their lack is not the cause of your problem.

    5. It's possible that the pattern of ice-build up on your roof gives you clues about where the heat is leaking into your attic.

    6. Is there enough clearance at the perimeter of the attic (near the eaves) for the required full depth of insulation? If the height is insufficient to allow R-49 insulation plus a vent channel above, you may need spray foam at your attic perimeter.

    7. In case you missed it, here's a blog I wrote on ice dams: Prevent Ice Dams With Air Sealing and Insulation.

  3. David Fay | | #3

    Rather than just air sealing and crossing your fingers, you could find someone skilled with a blower door who can test how much air actually leaks into your attic. Not everyone with a blower door knows how to do this, but some do. Air sealing can be done while repeating this measurement so you would know for sure how tight you got it.

    Energy Metrics

  4. Jake Swenson | | #4

    Thanks all for the helpful suggestions. As a follow up to some additional questions from responders, CSG ran the program and did building envelope analysis but pretty sure they sub most analysis and installation work out. They spent .5 days air sealing but pretty sure they didn't take up boards in narrow walkway that runs across center of attic to insulate under or air seal there and not sure how much sealing they did around the cans or under existing fiberglass. Door entry to attic is covered with 2" polysocyanurate and air sealed and has a seal at bottom opening. They air sealed and added insulation up entire stairs to attic. We had 8" of additional cellulose blown in across entire attic. I don't believe they put any channels or barriers at perimeter, they just blew it everywhere. I found the original report from CSG from back in 2005 and they did a blower door test as part of initial work. Pre-air sealing it read 4091, post it was 3220. No idea if that is good or bad. I don't see many hot spot areas on roof and we had good amounts of snow remaining on roof late into winter, but we still just get significant ice dam formation. Roof slope is pretty steep too in problem areas. I recounted and we actually have 12 recessed lights total. I'd agree we likely need additional air sealing to help insulation do its job.

  5. Robert Hronek | | #5

    I think many times calling out trades people to craft a solution is the wrong approach. Their job is to use their company's products and services to do the job. In many cases this is not the optimal solution. For one many/most of them will not use advanced diagnostic tools to get at the root of the problem.

    Personally I think you want to find an energy auditor to come out with a blower door and a camera. A blower door can be operated to pressurize a home or depressurize. When the door is pressurizing a home it is blowing air into the house and out the leaks. In doing so the leaks can be found from the attic side.

    Now going off of what you said is that there are not soffit vents. I think it is totally ridiculous that other work was done prior to putting in proper soffit vents and vent chutes. There is an order to do things. Going back in to disturb insulation to install soffit venting is wrong. This goes back to tradesman selling their good/services.

    I also think it was ridiculous to not address the can lights are part of the original work.

    The 3rd thing is the attic access should have something greater than an r12-13.

    I think in many cases we need to promote the use and benefits of advanced diagnostics. There needs to be more testing- going in and coming out. A proper audit would have identified your deficiencies and give an ordered course of action. The course of action would have been 1) soffit vents and chutes 2) address can lights 3) complete air sealing even if it meant removing existing insulation 4) Insulation.

    The roofer should have mentioned the lack of soffit vents. IF he did not then I would be suspect of his work.

  6. David Meiland | | #6

    I agree with David Fay's suggestion to re-test the house and measure house wrt attic is a good one. The result will probably be that the attic is well connected to the house. The failure to completely move the fiberglass out of the way was fatal. Robert's suggestion of IR is also good. It is really easy to see heat leaks coming into attics that way. Here are an image of a can light (not on) and typical FG in an attic.

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