Traditional Ice Dam Solutions

Ice dams aren't new to this region. How did New England homeowners traditionally solve the problem? With copper snow belts, copper gutters and copper gutter liners. This metal's superb ability to conduct heat uses the very warmth that is creating the problem to eliminate the ice dam altogether.

Typically ice dams are fed by two sources of snow melt. Warm air, rising between the inner and outer wall ends up in the soffit*, the boxlike structure just behind & below the gutter. This can be addressed by ventilation in most cases. But the other source is sunlight, slowly melting the snow pack even on the coldest sunny days. Water trickles down the roof till it gets to the gutter. Then it freezes up overnight. There is no practical way to prevent this melt. As the dam builds up from the gutter, snow melt rises behind it just like a reservoir. As the lower portion of the roof is submerged, pressurized water literally runs uphill. Overlapping slates or shingles are designed for water to run downhill. When it rains on top of a heavy snow pack with ice dams at the eaves** you get a bathtub effect. If there's a quick freeze before the ice dam melts and/or slides off the process starts all over again.

If the only damage you see from the record snowfalls of this winter is a tiny stain here or there, count yourself lucky and forget about it. But be sure to check the exterior for damage, too. Ice dams can ruin a paint job, force the mortar out from between your bricks or cause the stucco to bulge and crack. Spotting damage to paint is obvious. For masonry, look for icicles sheeting down the outside wall. With stucco exteriors, dark, wet stains are the telltale sign. ALL the damage is covered by your home-owner's policy. Some policies cover removing the ice dams to mitigate further damage.

Copper snow belts running at least 3'-4' up the roof, properly soldered to a copper gutter or gutter liner is the only surefire solution to ice dams on a slate or tile roof. This allows the lower portion of the roof to be completely submerged without leaking. But unlike well ventilated asphalt roofs, snow tends to slump to the bottom of slate or tile roofs. When the snow pack reaches the warmer smooth copper snow belt it slides right off, taking down what ice has formed overnight. Because the copper gutters and liners conduct heat so well ice is rarely frozen solid to the bottom of the gutter so it slides out too, often leaving half round lengths of ice in the snow below.

Modern solutions like heating cables are usually problematic in general. For slate & tile roofs, they are worse than that. Wherever you end your cables there's a problem. You've generated more melt to freeze up. If you stop at the bottom of your downspout a huge block of ice can form and the water can back all the way up the downspout. On a slate roof, the slumping snow pack tends to yank the cables loose after a couple of heavy winters. Then you've got dangling electric cables, possibly damaged, on top of wet snow and ice. Not a good combination.

Properly applied, a 6' belt of ice & water shield can work in many instances, especially if the dams are not severe. But ice and water shield won't adhere well to old dusty roof boards and the most vulnerable spot is often just below, where the fascia board meets the roof boards right above the gutter. Ice & water shield sticks best to smooth clean metal. Sealed to the apron*** of a copper gutter or liner, this can often be an effective solution. If copper is out of the budget, we recommend an aluminum flashing covering the fascia board (behind the gutter) with a 6" apron going up the roof with 6' of ice & water shield on top.

Letting large amounts of snow sliding off slate roofs over ssidewalks, driveways, entries and landscaping is impractical or downright dangerous. Heavy duty snow rails, secured to the rafters at least 3" above the roof edge, ideally above a snow belt, holds the snow-pack back from avalanche. Then it can slowly melt away. If the gutters and downspouts are frozen, icicles will still form but not ice dams.


*The vertical board behind the gutter is the fascia board, the horizontal board just below the gutter is the soffit board. If you have exposed rafters or an open soffit, consider yourself fortunate.

** The part of the roof overhanging the outer wall.

***The part that rests flat on the roof.

Year 2015