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New Roof and Ice Dam Prevention - One Family's Story

[Update: the winter of 2004 was another ice dam year. I received several inquiries so I added an update section. In 2019 I came across a fairly definitive 1977 U of Minnesota Extension booklet on ice dams. Very little has changed since then!]

In the winter of 1997 we experienced severe ice dams and considerable interior water damage. We had three things going against us: a severe freeze thaw cycle, a finished attic with inadequate knee-wall insulation, and no ice-water shielding on the roof.

In the spring of 1997 we attempted to eliminate the problems we could control. We thought we chose contractors carefully. We did not take the low bid, in fact the bid we accepted was moderately high. Despite that, we had a number of problems. This snippet describes lessons learned and what we would do differently in the future. It first describes the steps we took to reduce future ice dams. After reviewing what's done for ice dams I don't think there's much real data to support most measures. I think a metal roof (as in French Canada) or a Scandinavian dual-roof system are probably the only things that really work. In fact, as of Feb1998, we again had ice dams. Fortunately the weather was less severe, and the ice and water shields (see below) were in place.

Parenthetically, I think there's a vast fortune to be made by an entrepreneur who establishes a national high quality, high tech, roofing solution including installation.

Ice Dams - Looking back to 1997 from 2004

• In 1997 expert opinion was that stopping warm air flow to roof areas and insulating would solve ice dam problems. In 2004 the experts are more realistic. Some roofs and houses are so prone to ice dams that, under the "right" conditions, ice dams will form no matter the interventions. Old houses with complex roofs and an attic turned into a living space are ice dam magnets.
• If you have a problem house you need to watch for early ice dam formation, or heavy snow accumulation, and hire someone to shovel your roof. This will cost you from $0 to $1000 a winter depending on your roof, weather, etc; I expect it will reduce our roof's life expectancy by 3-8 years. You can try a roof rake, but if your roof gets ice dams chances are it will be hard to clear by roof rake. Don't try to shovel your own roof unless your life is worth less than $1000. Try to phone before the shovelers are swamped with calls. If the newspapers start talking about ice dams it's too late to find anyone. Ideally you should ask for proof of insurance -- shoving roofs is hard and dangerous work. Expect to pay real money.
• I see so little use of warming systems and wires that I suspect they don't work -- or that it would be almost impossible to find anyone to properly install and maintain them.
• With the preventive steps we took in 1997 (below) we end up needing to hire roof shovelers once every 2-3 years. The real cost is the injury to our shingles. We may tear off the top half of our home and put in a true second story with well designed ridge vent and soffet structures. We need the space and that will resolve the problem. Other than tearing off a finished attic the alternatives is probably a metal roof. Metal roofs are getting much more popular, in the past their main weakness has been noise, hail damage popping seams and rivets, difficulty finding trustworth and experienced installers, and cost.

Ice Dam Prevention Steps

• Professional insulators opened up the knee wall floor boards and blew in insulation, then covered the floor boards with further insulation. They also installed vents in each knee wall compartment (they entered some of the knee walls through the roof!). I'd wanted to install a ridge vent, and have passive air flow from a lower compartment vent up through the ridge vent. The way the attic was finished did not allow this. (poor design). We also considered forced air electrical vents, but no-one here was comfortable putting those in.
• Ice and water shields 9 feet up. (Weatherwatch)
• I wanted to install a WaterFall Gutter Guard system. I'd read that it can keep snow out of the gutters in heavy falls, preserving a drainage area during freeze-thaw cycles. Unfortunately our gutter installers put the gutters so close to the shingles there was no way to install this. (May have been limited by apron use, see below.)
• I installed new steel gutters with an apron that went under the ice shield and shingles atop the apron. The goal was to reduce ice flow moving up from the gutter and under the shingles. Not sure if this will help.
• I noted ice moved up underneath our valley liner overlaps last year. I tried to get those sealed. I don't think this was done properly. The roofers we dealt with didn't know how to do this.
• I wanted heating tape for the valleys and gutters. The roofers had so much trouble with the basics I gave up on this.

Lessons Learned and What I Wish I'd Done Differently

• We called a local well-known "roofer of the rich" for an estimate. That company employs its roofers. They sent their estimating company, which recommended another related company for which they did the estimate. That company shares ownership with the high end roofer, but it turned out it had few employees. It is basically a shell company. The "supervisor" gathered roofers and put them to work. Before signing a contract, I should have understood the relationship of the people doing the work to the people who ran the company.
• The supervisor had too many jobs, and was rarely available. He was an adequate supervisor when he was available, but the crew needed more supervsion. They had many questions no-one could answer. Ask Who will be the on-site supervisor? How many hours a day will he be on site? Get it in the contract!
• Ask who will do the actual work? It may not be the experienced people you speak with, but rather people who've never been on a roof before. You will speak with the helpful salesperson only at the time of sale.
• Find out how problems and issues will be handled.
• Make sure everyone has in writing what contractors will do what. Try to establish a sequence: roof, then insulation, then indoor repairs.. Our insulation people thankfully took over vent placement from the roofers.
• Get timelines, but be clear on what happens if they run over. Consider a penalty clause for late completion in the contract. Beware artificial timeline (2-3 days for "small job")
• The roofers ended up cutting our shakes to put in flashing, and left instead an ugly insert. Be clear in the contract how shakes and flashings will be handled.
• Read several small roofing books. (Of course we did this too ... sigh.)
• Don't be deceived by quality of the estimator and salespersons. May have no bearing on work quality. I'm not even sure there's a relationship between price and quality.
• Communication can be a big problem between contractors, workers, etc. Messages often lost or misplaced. Try to get things written out as much as possible.
• Get full names of all salespersons, contractor, supervisor, local supervisor. Who owns the roofing company?
• Call the National Roofing Contractors Association. Ask for a copy of their pamphlet and a list of local members. 847-299-9070, fax 847-299-1183. This can take a while to arrive! See about an express shipment or fax the list of local members to you.
• Lastly, there's not much science that I can see behind what contractors usually do. There is experience, but there aren't the randomized controlled trials that are needed to settle opposing views that are well argued and based on equal experience. Opinion and experience only goes so far; this field needs a bit of science!

Good Luck.

Descriptors
Confidence (1 to 3): 2. Date Created: 6/19/97. Last Revised: 2/1/98. Expires: . Language: english. Domain: .us. ID: 13. Topic: world. Subtopic: . Keywords: roof; house; home; ice dam; contractor; problems; gutter.