Hail rating
What a Class 4 rating tells you, and what it doesn't
UL 2218 is a lab test: steel balls dropped onto a panel, then a look for cracks. Class 4 is the top class. It is useful, and it is easy to read too much into.
| What it doesn't | What it tells you | |
|---|---|---|
| The panel | What it doesn'tThat it won't dent. Cosmetic dents can pass. | What it tells youIt did not crack in the test. |
| Your roof | What it doesn'tHow your roof will do. Thickness, deck and support all matter. | What it tells youHow that product did on a test deck. |
| Your insurance | What it doesn'tThat yours does. Each company decides, and some policies exclude cosmetic damage to metal. | What it tells youThat some insurers look at the rating. |
| The installer | What it doesn'tWhether the roof was installed to the maker's instructions. That is the crew's job. | What it tells youNothing. |
After hail
A dent is not always a leak
On a metal roof we separate looks from function, because they are different questions with different answers.
A dent in the flat of the panel
Usually cosmetic. The panel still sheds water. Your policy may treat cosmetic damage differently, so read it.
A dent at a seam, trim or fastener
Worth a close look. Seams and trim are where water and wind get in, and a distorted one may need repair.
A crack, an open seam or a loose panel
That is a function problem. We photograph it, say what it takes to fix and give you the paper to share with anyone you choose.
Snow retention
Four steps to a snow guard layout
We do this before we order panels, because the answer can change which panel makes sense.
- 01
Step 1: Walk the ground
We look at every spot under an eave: doors, walks, decks, gates, meters, tanks, vehicles and the roof below.
- 02
Step 2: Choose the guard
Clamp-on guards for a standing seam, so no hole goes through the panel. Screwed and sealed guards for exposed-fastener panel.
- 03
Step 3: Set the rows
Steeper, longer roofs and heavier snow need more rows. We set them from the pitch, the panel and your site, and we explain the choice.
- 04
Step 4: Mark it on the estimate
A simple drawing of the roof with the guards on it. If you want more or fewer, we change it before you sign.
Why snow lets go
Steel is slick, and a chinook makes it slicker
A warm wind can melt the bottom of a snow load while the top stays put, and the whole slab goes. Guards give it something to hold, so it melts away a little at a time.
A load of snow can hurt a person, a car or a gutter.
Ice dams come from heat in the attic, not from the metal, so we also look at ventilation and insulation.
Hail and snow
Questions about hail and snow
What is a Class 4 rating, and will it lower my insurance?
Class 4 is the top result in the UL 2218 impact test, which checks whether a panel cracks when steel balls are dropped on it. It is a product rating, not a contractor credential. Some insurers lower premiums for Class 4 roofs and each company decides, so ask your agent. Some policies also exclude cosmetic damage to metal roofs.
Will hail dent a metal roof?
It can. A thicker steel panel on a solid deck dents less, and a panel can pass a Class 4 test and still show dents. We tell you what a dent does to the roof's job, which is often nothing, and what it does to its looks, which is a separate question your policy may treat differently.
Why do I need snow guards on a metal roof?
Steel is slick, and snow on it lets go in one piece. Guards hold the snow on the roof so it melts off a little at a time instead of landing on a door, a walkway, a lower roof or a stock gate. We mark where they go on the estimate.
Can a metal roof still get ice dams?
Yes. Ice dams come from heat escaping into the attic, not from the roofing. Air sealing, insulation and ventilation do the work, and we look at them at the visit.
Does a metal roof attract lightning?
No. Metal does not make a strike more likely, and steel does not burn. If lightning is a worry on your property, an electrician can look at grounding for the building.
Want the layout drawn for your roof?
Tell us what is under your eaves. We will mark where the snow must not land.