With help, that gutter might still be on the house

Inspector's Eye

Don't let snow and ice do so much damage

March 09, 2003

Ice and snow pulled the rain gutter off one side of our roof after the heavy snow we had recently.

What can be done to prevent a recurrence?

Quite a few houses lost gutters to the recent ice and snow. A slate-roofer friend tells me he is swamped with gutter repair calls.

Most fallen gutters are brought down by the weight of ice that accumulates in them and above them. Extended periods of freezing temperatures while roofs are snow covered is a formula for heavy ice build-up - snow melts off relatively warm roof surfaces, then refreezes when it reaches the gutters and eaves.

Gutter damage also occurs when heavy snow falls from steeply sloped roofs, taking the gutters with them. Slate and metal roofs are quite vulnerable to this because of their smooth surfaces. Snow sliding can be prevented by installing snow guards - devices mounted on the roof surface to hold snow in place. Snow guards can be retrofitted and come in various styles.

The best solution to reducing ice build up is improving attic ventilation.

One way to do this is to provide adequate air circulation from the attic down into the eaves. At the lower edges of the attic, where the roof extends over the outside wall of the house, insulation often blocks air flow under the roof surface. The blockage prevents attic warmth from reaching the part of the roof that extends over and beyond the outside wall -- that's the part above the eaves.

Colder temperatures over the eaves creates a condition where snow melting off the warmer part of the roof can refreeze at the eaves, piling ice onto the roof and gutter. This also can cause water to back up under the shingles, often resulting in roof leakage.

The solution to poor ventilation over the eaves involves creating an air space between the underside of the roof and the top of the attic insulation, either by pulling some insulation out of that area or by installing vent channels above the insulation. Vent channels are cardboard or plastic foam baffles that are placed under the roof surface to hold the insulation away from the roof, creating a continuous air space from the attic to the eaves.

All new homes employ vent channels, but homes older than 5 years often lack them. The channels cost $1 to $2 a piece and one is needed for the space between each pair of rafters. Vent channels can be retrofitted. However, access to areas that require them is restricted by the lack of overhead clearance, so it's a good job to hire an insulation contractor.

Also, keeping the attic cool can reduce the amount of snow melting off the roof while outdoor temperatures are below freezing. Adequate venting between the attic and the outdoors is important to cool the attic and will prevent potentially damaging moisture buildup as well. A convenient time to install additional attic venting is when the roof is reshingled. Additional insulation in the attic will prevent heat loss - just be sure to use vent channels at the eaves.

A time-honored approach to preventing ice damage on roofs in the Northeastern United States is the use of heating strips or heat tape on the lower edges of the roof. But it involves the use of electricity in a wet environment so it should be employed with great caution, if at all.

Finally, gutters can be reinforced to withstand winter's onslaught. Most gutters are only minimally attached to houses, especially seamless aluminum (K-type) gutters. Installing additional gutter brackets or spikes will help them stay in place through all types of weather. They also will be appreciated by anyone who has ever leaned a ladder against a flimsy gutter to get on the roof.

A type of stainless-steel gutter bracket that can easily be retrofitted into seamless aluminum gutters is available at home centers. These are quite strong and seem to perform well.

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