Metal Roofs and Thermal Function

I bought an old house last year that needs to have its roof replaced pronto. The contractor I've been working with recommended replacing my current asphalt roof with metal, which seems preferable in many ways. I know it will be more durable and better for rainwater collection.

I am concerned, though, about metal's heat absorption turning my home into an oven in the summer and icebox in the winter. Last year I was able to go without air conditioning in the summer despite numerous 100-degree days, but there was quite a bit of heat gain over the course of the day, much of which I assume came from the south-facing roof. I am worried that a metal roof might be even worse (For what it is worth, my attic currently has an insulation amounting to value of R-32, according to the electricity company auditor.).

All of the advice I have seen suggesting metal roofing will not make a house hotter is suspect because 1) it is in the form of marketing propaganda from roofing companies, and 2) any such recommendations undoubtedly assume constant use of air conditioning.

Give it to me straight: will a metal roof make my non-air-conditioned home hotter in the summer (or colder in the winter) than my current asphalt roof? If so, is there any affordable method to improve the thermal function of a metal roof?

Angel Hunt wrote:I bought an old house last year that needs to have its roof replaced pronto. The contractor I've been working with recommended replacing my current asphalt roof with metal, which seems preferable in many ways. I know it will be more durable and better for rainwater collection.

I am concerned, though, about metal's heat absorption turning my home into an oven in the summer and icebox in the winter. Last year I was able to go without air conditioning in the summer despite numerous 100-degree days, but there was quite a bit of heat gain over the course of the day, much of which I assume came from the south-facing roof. I am worried that a metal roof might be even worse (For what it is worth, my attic currently has an insulation amounting to value of R-32, according to the electricity company auditor.).

All of the advice I have seen suggesting metal roofing will not make a house hotter is suspect because 1) it is in the form of marketing propaganda from roofing companies, and 2) any such recommendations undoubtedly assume constant use of air conditioning.

Give it to me straight: will a metal roof make my non-air-conditioned home hotter in the summer (or colder in the winter) than my current asphalt roof? If so, is there any affordable method to improve the thermal function of a metal roof?

My experience building has been no. The asphalt shingles will actually absorb more heat most of the times due to their colouring. Choose a lighter colour and make sure they include a ventilated top cap and you have ventilation in the soffits. Some people will also install a solar powered fan to force airflow.

Most buildings where I live use metal roofs.
I imagine shingles would weight more or very similar to a metal roof.

I purposely purchased castle white or whatever they called it for my roof for the purpose of reflecting heat.

Another thing is its super quick installing metal roofing. So labour costs are most likely minimized. Where as with shingles each shingle needs to be attached. A piece of metal roofing covers 10' by 3' for example.
So there might be a labour savings installing metal roofing over shingles.

The metal will also not stink in my experience. I remember asphalt smelling quite bad afterwards/during install.

Another thing is when the metal roofing eventually wears out or gets damaged somehow. Often they are usable for animal shelters/garden beds walls/covering lumber/covering stuff,etc, etc
Not so with shingles... mostly tossed


If you really want a roof which will last. consider metal roofing that hides the fasteners.

Our previous house was quite large, and we built it with a metal roof as we had bad experience with shingles on previous homes in our hail-prone area, and we were building the home with energy-efficiency as one of the main objectives. Asphalt shingles are heavy, usually darker colors, and retain a LOT of heat. We spray-foamed and sealed the entire envelope. The steel roof helped to reduce the heat gain in the summer, compared to asphalt, and the steel will cool faster after the sun goes down. We lived there for 16 years and the roof withstood several hail storms with minimal damage. Standing seam steel is the way to go for sure, if you can afford the upfront cost difference. We just completed build of a shop building at our new-ish property, and it has a steel roof (it is an all-steel bolt-up structure), this time we were able to go with an even lighter color, to help in the hot months.

One more consideration - a steel roof is better for rainwater harvesting, particularly if considering potable water.

We bought an older house with a metal roof, painted dark brown. In the incredible of 2020, we had a heat wave of 110-116 degrees over several days, with little  cooling at night (think it was in the 90s overnight). Had no air conditioner. Hottest it got in the house was 82.

I have a lot of experience with metal roofing.
And the advise from the others is correct, metal roofing is probally slightly better than asphalt because the metal roofing will not hold heat as a thermal mass
A metal roof will get as hot as any other roof, but it will cool as soon as a cloud comes over.
If metal roofing is insulated with the correct products it will be fantastic.
I worry when I see a comment like this .,,....." I suspect company information because ......
1) it is in the form of marketing propaganda from roofing companies,
2) any such recommendations undoubtedly assume constant use of air conditioning.
My response is
1 any information has to comply with laws and that can be tested
2 There is no evidence that air con use is an assumption. It would be stated if it was.
   I have never seen such data presented in such a manner.
Because metal roofing is not used often in NOrth America I see plenty of mistakes but if insulation, ventilation and installation
is done properly you will have a great long lasting roof.
Easily with a 100 year life.

A critical point is to use the brightest white metal roofing you can get. This will reflect much of the sun's heat.

When my parents built their ranch style house in the late 1950s, they installed black mineral surface roll roofing. When I helped reroof it as a teenager, we switched to white mineral surface roofing, and it made an immediate difference in interior summer temperatures.

Thank you all so much! You allayed what concerns I had.