How Snow Load and Ice Pull Gutters Off the Fascia

The ice that fills a gutter mostly forms on the clear days after a storm. Afternoon sun melts some of the roof snow, the water runs into the trough, and once the sun goes down it freezes before it can reach the downspout.

Run that cycle through a week of February weather and the gutter fills with ice one layer at a time. Once a downspout freezes shut, every round of melt has nowhere to go but the trough, so the ice builds even faster.

Debris speeds the whole thing up, because wet leaves, pine needles, and cottonwood fluff hold water in place. A gutter packed with them ices up far more than a clear one.

Water runs through a gutter and drains away, but ice stays put, and each cycle adds to it along with the snow piled on top and the icicles hanging off the front edge. All of that weight sits on the hangers, and the hangers hold on by the screws driven into the fascia.

Sliding snow adds a different kind of stress. The steep roofs on a lot of newer two-stories around Westminster and Broomfield can let a whole slab go at once, and it catches the front of the gutter on the way down, pushing it outward and down. That's why hangers belong closer together wherever snow slides off the roof.

When one hanger lets go, the ones on either side pick up its share. A single soft spot in the board can turn into a sagging run that way, and a heavy enough load can rip the gutter right off the fascia.

Once a gutter pulls away from the board, even a little, meltwater starts running down behind it and onto the fascia. A hard winter can leave the board softer in spring than it was in the fall.

Every house on the street gets the same storm, but the gutters that pull loose usually had a weak point before the snow arrived. The common ones:

It starts with what the gutter is screwed into. Hangers driven into solid fascia hold under loads that would pull them straight out of soft wood, so a rotted board gets replaced before a gutter goes back up on it.

Spacing and pitch come next. Hidden hangers go in every couple of feet and closer together where snow slides off, and each run is pitched toward its downspout so water keeps moving.

Clearing the troughs before the first freeze matters, too. A gutter that isn't packed with wet leaves freezes far less, and guards can help on houses under big trees or close to the foothills, though no guard prevents ice dams by itself.

Ice dams higher up the roof add to the load, since the ice they build at the eave still ends up hanging on the gutter. Keeping house heat out of the attic takes weight off the hangers too, because less meltwater reaches the eave to freeze.

Most of the warning signs are visible from the yard, so walk around the house after a big storm and again once things thaw. Skip chipping ice out of the trough or setting a ladder on frozen ground, since both are more likely to damage the gutter or hurt you than help.

Icicles along the front edge are a warning sign of their own. A thick row of them means water is spilling over the gutter instead of draining through it, and all of that ice is weight the hangers have to carry.

As the snow melts, put back any downspout extensions that got knocked off or buried, so the melt drains away from the foundation.

A section that moved once has usually found a weak spot in the board, and it will keep working at that spot every storm until the wood is fixed. Look for:

Plan the repair before the next big snow if a storm has pulled your gutters loose or left the board behind them soft. Stoked's fascia repair replaces the soft wood first, so the gutter goes back up on a board that can hold it.