No, Steel and Wood Don’t Have the Same Fire Rating

I saw a comment on one of our TikToks recently, someone claimed steel and wood carry the same fire rating. I read it twice to make sure I was comprehending, then I had to move on.

Because the thing is, one of these materials is literally used to build fire pits. The other one burns inside said fire pit.

So I figured this deserved its own blog post. Not just for whoever left that comment, but for every homeowner and contractor who’s ever asked about fire ratings and not gotten a clear answer. Here’s what a fire rating actually means, why you should care, and how steel really stacks up against wood, asphalt, vinyl, and everything else on your house.

What a Fire Rating Actually Means

Fire ratings come from a test. Roofing gets tested under ASTM E108, sometimes called UL 790. Siding and other building materials fall under ASTM E84, or UL 723. Either way, the test measures how a material behaves when fire hits it. There are three classes.

Class A is the top rating. Best protection against severe fire exposure. Resists flame penetration. Doesn’t feed the flames.

Class B is solid but a step down.

Class C gives you light protection, mostly against fire coming from outside the structure.

If a material fails all three tests, it’s unrated. Some people call that “non-rated.”

Here’s where people get tripped up. A fire rating can belong to a whole assembly — the roofing or siding plus backing, underlayment, maybe a fire-retardant coating. Or it can belong to the material itself. Steel earns its rating the second way. The metal doesn’t burn, wood does. Whether it’s a shake roof or cedar siding, wood is combustible by nature. You can treat it with fire retardant, sure. That costs extra, it’s not standard practice, and the treatment fades over the years as weather beats on it. Steel skips all of that. It’s non-combustible straight out of the coil.

Why This Matters If You’re a Homeowner

A fire rating isn’t just a number buried in a spec sheet. It shows up in decisions you actually make.

Insurance. A lot of insurers knock money off your premium for non-combustible roofing and siding. In wildfire-prone states, some are starting to require it outright. Even here in Indiana, where wildfire isn’t the headline risk, insurers are paying closer attention to exterior materials than they used to.

Embers and flying debris. Grass fires happen. Brush fires happen. So does the occasional structure fire next door. Embers land on roofs and blow up against siding all the time. Non-combustible materials give those embers nothing to work with. Wood does the opposite.

Resale value. A Class A, non-combustible exterior is a selling point.

Why This Matters If You’re a Contractor

It’s a real differentiator. Picture a homeowner comparing quotes. “This is Class A fire rated steel, non-combustible, no treatment needed” beats anything you can honestly say about asphalt, vinyl, or wood.

It answers the insurance question before your customer even asks it. More homeowners are calling their agent mid-decision these days. If you can explain the difference between a material rating and an assembly rating without stumbling, you sound like the guy who actually knows the product. Because you do.

How Steel Compares — On the Roof

Let’s put steel roofing next to what’s still on most houses in America: asphalt.

Asphalt only hits Class A when it’s part of a tested assembly. The mat underneath is doing most of the heavy lifting, not the shingle itself. Steel doesn’t need that crutch.

How Steel Compares — On the Walls

Now the siding matchup. Steel against the two materials it actually competes with on real bids: fiber cement and vinyl.

Fiber cement holds its own here. It’s built to be non-combustible from the factory. Vinyl doesn’t and it can spread fire instead of stopping it.

The gap here is not close. Steel isn’t squeaking by on a technicality. It’s playing a different game than wood entirely.

Our Steel: Class A Fire Rated AND Class 4 Impact Rated, American Made

Indiana Metal’s panels — roofing and siding, both — carry a Class A fire rating because the material itself is non-combustible.  And since Indiana weather doesn’t stop at fire risk, our roofing panels also carry a Class 4 impact rating, the top score under UL 2218. That means they’ve been tested against hail and impact harder than lower-rated materials ever will be.

It’s all roll-formed here in the U.S., fabricated at our Bainbridge facility and available for pick up at our Bainbridge OR Indianapolis location, or we deliver.

Class A fire rated. Class 4 impact rated. American made. Not many materials can claim all three, on the roof or the wall, but steel can.

Weighing your roofing or siding options? Need real documentation to back up a fire rating conversation with a customer? Call either location, we’d love to help.

Indiana Metal  •  indianametal.com  •  Bainbridge: 765-657-2828  •  Indianapolis:  317-907-7777