A metal roof suits a Palouse winter because its smooth surface lets snow slide off rather than build up. The same shedding can drop a slab of snow onto a doorway, a walkway or a parked vehicle. Snow retention exists to hold that snow in place wherever people and property sit below the eave.
Key takeaways
- Metal roofs are common on the Palouse because the surface sheds snow rather than holding it for long.
- US patent filings describe the trade-off: the low friction of raised-seam metal lets snow slide in ways that can be hazardous.
- The hazard follows the fall line, so the doorways, walkways and parked vehicles under the eave decide where snow retention goes.
- Snow guards hold snow in the roof plane and are laid out entry by entry rather than counted by the roof's square footage.
- Valleys, parapets and roof offsets concentrate snow, and Moscow's amended building code requires designers to consider that buildup.
- A roof's remaining life is judged by its condition, including the decking and framing, rather than by the age of its covering.
Why do metal roofs shed snow in the first place?
A smooth metal surface, especially a raised-seam panel, offers little friction, so snow tends to slide rather than stay put. Designing for snow shedding is one reason metal is chosen in snowy regions.
US patent filings describing snow-retention devices note that in some regions metal roofs are designed to shed snow, which limits the buildup that could damage or collapse a structure. The same filings describe the trade-off. Friction between the roof and the snow is low on a metal roof, including raised-seam roofs, and that low friction is the condition in which sliding snow becomes a hazard to people, property and the surrounding ground.
For a homeowner, that is the central idea. A metal roof is not chosen because it stops snow. It is chosen because it does not hold snow for long, and the snow it releases has to go somewhere. Whether that suits a given house depends on what sits below each eave and how much snow the roof collects, which is a question about the roof's shape and its walkways as much as the material.
Where does the snow go when it slides?
Sliding snow and ice can fall onto people, property and the surrounding landscape. The fall line matters most, because it decides which doorway, path or vehicle sits beneath it.
The patent literature warns that sliding snow and ice from metal roofs can be hazardous to people, the surrounding landscape, property and building components. The hazard is sudden. A slab that lets go during the night gives no warning to anyone walking under the eave, and a parked car does not move out of the way.
On a Palouse house the risk concentrates at the places people use: the front door, a side entry, the path from the driveway and any spot where a car is parked close to the eave. Walk the fall line before deciding on the roof. Stand under each eave in winter and ask where a slab would land, then mark those spots on a sketch of the house so the installer can plan around them.
What is snow retention, and where does it go?
Snow retention is a set of devices fixed to the roof so that snow stays on the surface rather than sliding in one mass. They are placed over the spots where people and property sit below.
Snow guards, also called snow retention, hold snow on the roof plane so that it cannot release all at once. Their job is to break up a slide before it starts. A guard set over a doorway is doing a different job from a row across the whole roof, and that is why the layout matters more than a count of devices.
Snow retention is a placement decision. The guidance in the sourced record is about where sliding snow lands, and the spacing and layout should come from the installer after the fall line has been walked. Snow guards and snow retention are the service that handles that layout, and it should be planned together with the covering rather than added after the panels are down.
Does a metal roof handle a Palouse winter better than asphalt shingles?
Metal and asphalt shingles carry snow differently, and the honest comparison depends on the roof, its pitch and the snow pattern. Neither covering prevents a sliding hazard by itself.
Asphalt shingles are the usual covering on Palouse houses, and they hold snow differently from a smooth metal panel. That difference explains why the two behave differently in a heavy storm. Metal sheds, and that shedding is both its advantage and the thing that has to be managed. The covering is only one part of the answer, and it cannot substitute for the fall-line check.
This guide does not give a lifespan for either material, because the record does not support one from a government or university source. Judge a roof by its condition instead: how the existing covering looks, how the decking performs when it is opened, and whether the framing can carry the snow the roof collects. Those observations decide whether a roof is ready for a new covering, whatever the material.
Does metal change the snow load a roof must carry?
Metal does not change the design snow load a roof must carry. That figure comes from the building code and is confirmed by the local building official, and Moscow and Pullman publish different criteria.
A roof is designed for a snow load, and that load belongs to the building code and the local official rather than to the covering. Moscow and Pullman publish their own criteria, and they are not the same. A figure taken from one city should not be used for the other, and a roof in either place should be checked against its own jurisdiction's rules.
Drifting and sliding concentrate snow where two roof planes meet. Valleys, parapets and roof offsets are where buildup gathers, and that is where additions and dormers tend to sit. The City of Moscow's amended building code says designers must consider snow buildup at valleys, parapets and roof offsets. Raise that point with any installer who works on a roof that has a valley or an addition.
Where does metal fit on a Palouse house?
Metal suits a simple roof plane with a clear path below the eave. It needs more planning where the house has entries, decks or parked cars under the eaves.
A simple roof plane with a clear path below the eave is the easiest case. Each entry, deck and parked vehicle under an eave adds a decision: guard that spot, reroute the path or accept the slide. Those decisions belong in the plan before any panel is ordered, because they change how the eave is detailed.
The surrounding country adds a wind question. Latah County is described as comprising much of the eastern Palouse, famous for its rolling hills, and that rolling terrain means exposure varies from one street to the next. A metal panel's fastening and its edge details matter most on the most exposed roofs. Ask the installer how the panels are fastened and how the edges are finished before choosing the profile.
What should a homeowner ask before choosing metal?
Ask where the snow will land, whether guards are planned over each entry, and how the valleys and offsets are detailed. Those three questions settle more than the panel's color or profile.
Start with the fall line. Walk the eave, find each door, path, deck and parked vehicle, and mark them. Then ask the installer which spots will get retention and what the layout looks like at each one. A complete plan answers where the snow goes, which is the question the material alone cannot answer.
Next, check the design snow load and the valley detail with the building official rather than a web page. Ask what the roof is designed to carry, and whether the valleys and offsets are detailed for buildup. Finally, ask about winter access. A roof that is hard to reach in January is hard to inspect and hard to repair in January, and that cost belongs in the decision.
When is a metal roof the wrong choice?
Metal is a poor fit when the eave sits over a busy entry with no room to guard it, or when the roof is hard to reach in winter. A roof with many valleys and dormers needs close detailing whatever covering goes on it.
A house with a front door directly under a long run of eave is the case where a metal roof needs the most work. If the snow cannot be guarded or moved to a safe spot, the homeowner should weigh the covering against that exposure before the panels go on. The answer may be a different covering, a different roof plane or a different entry, and the decision is best made before the work is booked.
A roof with many valleys, dormers or offsets needs careful detailing in any material, because drifting and sliding concentrate snow where planes meet. That is the sourced reason to look at the roof's shape before the covering. For a house on the Palouse, shape and winter work together, so the decision is best made with the roof in front of you. The metal roofing service page describes the work, and the ice dam guide covers the eave conditions that metal does not solve.
Frequently asked questions
Will a metal roof slide snow onto my walkway?
It can, which is the reason to plan for it. Metal sheds snow because its surface offers little friction, and the slide falls along the roof's fall line. Walk the eave in winter and mark the spots below it before deciding. A walkway that sits in the fall line should be guarded or moved.
Do snow guards stop all sliding?
They hold snow in the roof plane and limit how much can release at once. They are a placement decision rather than a guarantee, so the layout over each entry matters more than the number of devices. Ask the installer how the guards are placed relative to the doorways and the parked cars you have marked.
Is a snow guard the same thing as a metal roof?
No. The covering and the retention devices do different jobs. The covering decides how snow moves across the roof, and the retention devices decide where it can go. A house can have one without the other, but a metal roof over a busy entry usually needs both.
How do I know my existing roof can carry the snow?
Ask the local building official. The design snow load for your address is set by the building code and confirmed by the local office, and Moscow and Pullman publish their own criteria. The condition of the framing and decking is judged by inspection, since the covering alone does not show how the structure is doing.
Should I wait until winter to decide?
Decide before the fall, when a retention plan can be installed and the entries can be cleared. Deep winter makes it harder to walk the roof and to reach the eave for measuring. Book a look early in the season, while the roof is still accessible, and ask for the fall-line check at the same visit.
When should I call a technician about a slab or a dam?
Call when a slab has already slid, when ice hangs over an entry or when you want the fall line checked before the next storm. Phones are answered around the clock, and a visit the same day is possible only when a technician is free. Do not stand under a loaded eave while you wait.
Sources
This guide is general information for Latah County homeowners, not a substitute for an on-site inspection. Prices are estimates. See our disclaimer.