Royal Dane Roofing · Salt Lake City, UT · From the roof

Snow Sitting Still Is the Load Nobody Plans For

Most of the winter roof damage I look at was not caused by a storm. It was caused by snow that landed, stayed, got heavier, and then went through the same thaw and refreeze twenty times before spring. Nothing dramatic happened. The roof just got quietly worked on for four months, and the parts that failed were the parts where the snow had no reason to leave.

That is a different problem from wind or hail, which arrive on a date you can name. This one is about geometry. On a steep, simple slope, snow slides and blows off and the load never really accumulates. On the low-pitch sections that are all over the mid-century housing here, snow lands and stays, and it keeps getting denser every time it melts a little and refreezes.

South Salt Lake sits on the flat valley floor, running to postwar ramblers, small brick bungalows, and a growing run of new townhomes. Ramblers tend to carry long shallow runs, porch and carport roofs, and additions at pitches well below the main house. Those are the sections I look at in February.

Why Old Snow Weighs So Much More Than New Snow

Fresh powder is mostly air. It lands light and a roof barely notices it. What people miss is that the same snowfall, three weeks later, can weigh several times what it did, without a single additional flake landing.

That happens because of the melt and refreeze cycle that defines a Wasatch Front winter. A sunny afternoon in the low forties melts the top layer. The water percolates down into the snowpack. That night it drops back below freezing and the water refreezes, but now it is occupying spaces that used to be air. Repeat that a dozen times and you have converted a fluffy blanket into a dense slab.

The roof feels that as increasing weight in exactly the places the snow did not slide off. That is why the load question is never really about how much it snowed. It is about how long the snow stayed and how many cycles it went through while it was up there.

On a steep roof this barely matters, because most of it leaves. The moment you introduce a shallow section, you have built a container.

What a Shallow Pitch Actually Changes

Two things change on a low slope, and both matter more than the load.

First, water moves slowly. Asphalt shingles are lapped like fish scales and work by shedding water downhill fast enough that it never sits at a lap. Slow water sits, and at a shallow angle it can work sideways and upward under a course, particularly with any wind pushing it. That is why shingles have a minimum pitch at all, and why plenty of low-slope sections on older houses were shingled anyway because it was what the crew had on the truck.

Second, snow does not clear itself. A shallow section holds its snowpack through the whole cold stretch, which means the surface underneath stays wet and cold for months rather than drying between storms. Anything that is going to leak under sustained wet conditions will leak, and anything marginal about the installation gets found.

Add those together and you get the specific failure I see most: not a hole, but a slow persistent seep at a low-slope section that only happens in winter, dries up in April, and comes back the following January. Homeowners often assume it was a one-off. It was not. It is a geometry problem that recurs every year the snow sits.

Where the Snow Piles Up Instead of Spreading Out

Load is almost never even, and the uneven part is what causes trouble. Wind does most of it. Snow scours off exposed areas and deposits in sheltered ones, so a roof can end up with bare patches in one place and a deep drift in another after the same storm.

The predictable drift spots are all changes of plane. Where a lower roof meets a taller wall, snow sliding or blowing off the upper section lands on the lower one and stacks against the wall. Behind a chimney. On the downwind side of a dormer. In a valley, which is already collecting from two directions.

On the housing stock here, additions where two rooflines meet at an improvised valley are the ones I watch. A valley that was worked out on the fly rather than designed is already moving more water than it should, and in winter it is also collecting more snow than the slopes on either side of it. That combination is why the same few square feet of a roof account for a disproportionate share of the leaks.

Carport and porch roofs deserve a mention too. They are usually the lowest pitch on the property and the least inspected, because nobody goes up there and nothing under them gets damaged in a way you notice quickly.

What to Look for When It Melts Off

The honest answer about winter roof damage is that you usually find it afterward. So the useful habit is a spring look, when the snow is gone and before the summer cloudbursts arrive.

From the ground with binoculars, look at the low-pitch sections specifically. Lifted or curled edges where a lap has been pried open. Shingles that look displaced or out of line, which often means ice worked underneath and moved them. Any section that looks visibly flatter or dished than it did, which can mean the decking underneath has taken on water and sagged.

Then go inside and look at ceilings under those sections, and in the attic above them if there is access. A dried tea-colored stain on a rafter under a low-slope addition is the classic winter signature. It is dry in May because the snow is gone, and it will be wet again in January.

Check the gutter line while you are at it. Ice that formed and sat in a gutter all winter puts real weight on the fascia, and gutters that have pulled loose or changed pitch will not drain when the summer cloudbursts start. Small lots make that worse, because overflow has nowhere to go except the foundation.

If something looks off, get somebody on it. A lifted lap or a displaced course caught in spring is a contained repair. The same spot left through another winter is decking. Jeremy gets on the roof, photographs each slope separately, and tells you plainly which it is. Send us a note and we will come look, and there is more on how we work locally on the South Salt Lake page.

Quick Answers

Should I be raking snow off my roof?

On most steep roofs, no, and getting up a ladder in January to do it causes more injuries than it prevents leaks. Where it can help is pulling snow off the lower few feet of a low-pitch section from the ground with a roof rake, which reduces what sits there. Never chip at ice, which puts holes through shingles.

My low-slope porch roof leaks every winter but is fine all summer. Why?

Because it is a geometry problem rather than a hole. Snow sits on a shallow section for months, so water moves slowly and has time to work sideways under a lap. In summer, rain runs off fast enough that the same lap sheds it fine. That seasonal pattern usually points at pitch and the material chosen for it.

How much snow is too much for a roof?

There is no single number I would give you, because it depends on the structure, the pitch, and how dense the pack has become. What I watch for instead are the warning signs: doors that suddenly stick, new cracks in ceiling drywall, or visible sag in a ceiling line. Any of those in deep winter is worth a call the same day.

Does drifting really matter or is that overthinking it?

It matters, and it is the reason two houses on the same block can have completely different winters. Wind strips snow from exposed slopes and dumps it against walls, behind chimneys and into valleys, so the load concentrates in a few spots. Those concentrations are where I find the damage, not out in the open field.

Is spring or fall the better time to have the roof looked at?

Spring, if you are choosing one. Winter is what does the damage here, so a look after melt-off finds what the cold stretch actually did while there is still a whole dry season to fix it in. Fall is a reasonable second choice, mostly for clearing gutters and catching anything obvious before the snow arrives.