Ice Dams in Minnesota: What Gutters Can and Cannot Do

It is a familiar winter call: there is a ridge of ice along the edge of the roof, water is showing up on an inside wall, and the gutters look like the obvious suspect. Ice dams in Minnesota are a real problem, but they are an attic problem first, and the gutters are the part of the story most often blamed for something they did not do.

Here is what causes an ice dam, what gutters can and cannot do about it, and what a gutter system is actually for.

What an ice dam is

The mechanism is heat. Warm air escapes from the living space into the attic and warms the underside of the roof deck. Snow on the upper roof melts, the meltwater runs down to the eave, and the eave is cold, because it sits outside the heated part of the house. The water refreezes there.

Do that for a few days and the refrozen water builds into a ridge of ice along the edge of the roof. Meltwater coming down behind it has nowhere to go, so it backs up under the shingles, and from there it finds its way into the wall or the ceiling below.

What gutters can and cannot do

Gutters do not cause that, and removing them will not stop it. An ice dam forms on the roof, above the gutter, and it forms because the roof deck is warm in the wrong place. A gutter full of ice is a symptom of the same heat loss, not the source of it.

The fix is in the attic: air sealing to stop warm air reaching it, insulation to keep the heat in the living space, and a clear soffit-to-ridge ventilation path so the roof deck stays cold. We will tell you that even when the attic is not what you called about, because replacing gutters to solve ice dams is money spent on the wrong problem.

The same logic applies to anything that blocks that ventilation path. An addition that closes off a soffit run or dead-ends a ridge vent can show up as ice damming on the roof above it — a ventilation problem that looks like a roofing one. It is one reason the roof on a home addition is designed first rather than last.

What gutters are actually for

Gutters are the cheapest part of the building envelope and one of the most expensive to neglect. Everything they do is about keeping water away from the foundation, and many wet basements in the metro start at the roofline.

Seamless gutter is roll-formed on site to the exact length of each run, so the only joints are at the corners and outlets. Sectional gutter is joined every few feet, and each of those joints is kept watertight only by sealant, which has a service life. That is the whole argument for seamless: fewer places for a leak to start.

Size follows the roof. 5-inch K-style aluminum suits most Twin Cities roofs. Larger roof areas and steeper pitches shed more water faster and can justify 6-inch with larger downspouts — a calculation from the area draining to each run, not a preference. Downspout placement and quantity matter as much as the gutter itself: a long run with a single outlet can overshoot in heavy rain however well it is hung.

How a gutter is hung

Gutters are hung on hidden hangers screwed through the back of the trough into the rafter tails behind the fascia. The older method, spikes driven through the front of the gutter into a ferrule, can work loose as the wood cycles through wet and dry, which is one reason older gutters sag in the middle of a run.

A run needs a slight fall toward its outlet — enough to move water, not so much that it reads as crooked from the street. Too little and it holds standing water and debris. Getting that right on a long run is a matter of stringing a line rather than judging it by eye.

All of it depends on sound fascia. There is no point hanging new gutter on a board that will not hold a screw, which is why the fascia is checked before quoting rather than discovered on installation day. Rotten fascia is worth catching while the gutters are down, because doing both at once is one mobilization rather than two.

Where the water goes after the downspout

A downspout that discharges at the foundation has moved the problem four feet and no further. Extensions, splash blocks or a buried line to daylight carry the water far enough out that it does not come back through the basement wall.

It is the cheapest improvement available to many houses, and sometimes it is the whole answer to a damp lower level. If water is still getting in after that, the next place to look is the grade around the house, and finishing a basement should wait until the cause is settled.

Leaf guards

Leaf guards reduce how often a gutter needs clearing. They do not eliminate it: fine debris and shingle grit still accumulate, and a guard that clogs is harder to clear than an open gutter. Under mature trees they are usually worth it, particularly on a two-story where clearing means a ladder.

What we build

Stonevale installs seamless gutters, downspouts and leaf guards, and replaces the fascia, soffit, siding and trim they depend on. Where siding comes off, that is the moment to look at the water-resistive barrier and the flashing behind it. Our gutters and exteriors page covers the full scope and what moves the price.

Common questions

Will new gutters stop my ice dams?

No. Ice dams are caused by heat escaping into the attic, which melts snow on the upper roof; the meltwater runs to the cold eave and refreezes. The fix is air sealing and insulation in the attic, and keeping the ventilation path clear.

Should I take the gutters off to prevent ice dams?

It will not prevent them. The ice forms on the roof above the gutter, because the roof deck is warm. Without gutters, the water the roof does shed lands at the foundation instead.

Why does seamless gutter matter?

Sectional gutter is joined every few feet, and each joint is kept watertight only by sealant, which has a service life. Seamless gutter is formed on site to the length of each run, so the only joints are at the corners and outlets.

What size gutter do I need?

5-inch K-style aluminum suits most Twin Cities roofs. Larger roof areas and steeper pitches can justify 6-inch with larger downspouts. That is a calculation from the area draining to each run, not a preference.

Are leaf guards worth it?

Under mature trees, usually. They reduce how often a gutter needs clearing, but fine debris and shingle grit still accumulate. No guard removes the need to clear a gutter entirely.

Can you replace the fascia at the same time?

Yes, and it is worth catching while the gutters are down. The fascia is the board the gutter hangs from, so doing both at once is one mobilization rather than two.