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I'm considering a new roof for my suburban home. The home is about fourteen years old and the shingles are in so-so shape. We have had two leaks already and I've been told that means it is a good time to consider replacing the roof.

Rather than replace with another traditional shingle roof, I'm considering going with a metal roof. I've seen a couple in the neighborhood and they look nice, and I hear a metal roof will last a lot longer.

Aluminum and steel appear to be the two major products when it comes to metal roofing for residential homes. I'm not sure whether I should be considering aluminum, or steel.

What are the pros and cons of steel vs. aluminum metal roofing? That is, what advantages and disadvantages does steel roofing have compared to aluminum roofing, and vice-versa? If I go for one or the other type, what should I be looking out for and what should I be avoiding?

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I'm willing to bet the metal roofs are much noisier when it rains –  Joe Philllips Sep 30 '10 at 17:41
    
The noise should be irrelevant with a properly insulated roof. I have a hunch the type of metal is less of an issue in general and more about the particular type of application (standing seam vs. corrugated vs. metal shingles vs. metal tiles, etc.) –  DA01 Mar 29 '12 at 20:12
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6 Answers 6

up vote 12 down vote accepted
+50

The aluminum is probably more susceptible to denting, being a softer metal.

Will you ever need to walk on the roof? Do you have overhanging trees that may drop branches in a storm? Even trees near your house can see branches go flying your way.

Another question is the coating used. Since steel can rust, you don't want to worry about it. A high quality product would seem valuable there. Of course, you don't want to see paint flakes peeling off an aluminum roofing product either.

Finally, make sure that you can deal with snow, although this is not a factor that depends on the material itself. Our neighbor has a metal roof. A few years ago, we had a large, heavy snow fall, and a huge mass of snow broke free to slide off the roof. As it was coming down, it tore off the gutters on their home, then completely flattened part of their porch. My guess is it was several thousand dollars worth of damage. Falling snow can also damage plantings near the house. There are tabs that can be placed on the roof surface to prevent this if you live in the snow belt.

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Good point about the softer metal. We don't have many trees nearby that are taller than the house. We don't currently have any need to walk on the roof, but I did want to look into installing solar panels on the roof after a few years. –  Chris W. Rea Sep 27 '10 at 13:38
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The tabs are a critical part of metal roofs in snow country. Sounds like your neighbor had a legitimate complaint they could have filed against their roofer. –  DA01 Mar 29 '12 at 20:13
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It's been three years since I decided to go with a high-quality galvanized steel product. Revisiting my question and your answer, I'd like to reinforce what you said: the snow guard tabs are an important consideration when having a metal roof installed. I had the installer come back in the second year and add more to mine, after I witnessed how snow melted & slid off my new roof. –  Chris W. Rea Aug 7 '13 at 20:05
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Up/downs that I'm aware of:

  • Aluminum is more corrosion resistant.
  • Steel is more fire resistant without underlayment.
  • Aluminum is (at least a few years ago) more expensive.
  • There are a couple of different galvanizing techniques used with steel. Understand the differences that apply to your weather conditions.
  • Both roof types will likely outlive you.
  • Both roof types can display cosmetic damage from heavy hail, but offer a higher level of protection for the life of the roof. Asphalt will lose its protective ability over time.
  • You can offset the cosmetic issues by choosing roof patterns that will camouflage.
  • Noise from rain/snow/etc isn't an issue unless your installer is clueless.

I just did a roof, and couldn't afford metal. If I could, I'd choose based on the cost, local code and competence of the contractors offering the roof.

Roofing is an area where you need to be careful with low bidders. Make sure the roofer is certified by the roof manufacturer and is following manufacturer installation guidelines.

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One of the really great benefits of metal roofing is its ability to deflect heat which reduces cooling costs. This is because of its high reflective and emissivity (ability to release heat) qualities. Metal roofing is beneficial both in hot and cold weather. Its benefits are well documented.

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Not directly answering your question - but as you're replacing shingles with metal you'll need to make sure you insulate the roof well.

Otherwise it could get very hot in summer and cold in winter.

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Thanks. Could you elaborate on what you mean by "insulate the roof"? Do you mean the attic-space? We're at R-32 already; I am planning to take that up to R-50 next year. Also, I've been told that a metal roof would actually help keep the house cooler in the summer, as it would reflect more sunlight than a shingle roof. ? –  Chris W. Rea Sep 27 '10 at 13:36
    
@Chris - Given that metal is a better conductor of heat, you'd certainly get more heat loss in the winter and I'm pretty sure you'd get a lot of heat build up in the summer. However, if you're already well insulated (I'm not sure what your codes mean as I'm in the UK) then this shouldn't be a problem. I was just adding the answer for anyone else coming across the question. –  ChrisF Sep 27 '10 at 13:39
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I'm in Canada, brrrr, and R-32 above the top-floor ceiling is decent insulation. :-) Plus, the attic-space above that insulation is well-vented with outside air. Given the insulation and the vented air gap, I doubt heat conduction from the metal roof to the living space would be an issue. –  Chris W. Rea Sep 27 '10 at 13:54
    
@Chris - indeed not. Feel free to disregard my answer :) –  ChrisF Sep 27 '10 at 14:03
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I don't think you can say that a metal roof will make things VERY hot or cold compared to shingles. There's a lot of factors--color, install type, type of metal roofing, etc. One should, of course, have good insulation regardless. –  DA01 Mar 29 '12 at 20:16
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Aluminum does NOT hold heat, nor does it retain heat, better than steel. The opposite is true. Aluminum is a BETTER conductor of heat, therefore, it heats up much faster than steel, and, when the heat source is removed, cools quick. Since aluminum transfers heat more quickly, it will heat quicker and more evenly than steel, which is why cooks like it. Compare thick aluminum pans with steel or cast iron pans of even close to equal thickness and see for yourself. Thin steel pans get "hot spots" due to lack of quick conduction of heat. Aluminum roofs are about 1/3 the weight of steel, has very little corrosion. It tends not to hold paint as well. And screws/nails should be stainless or aluminum to avoid galvanic corrosion of the aluminum where dissimilar metals touch or get close to each other. Quality metal roofs have several layers of coatings which work well to prevent corrosion of steel roofs as long as it doesn't get badly scratched or when cuts are not sealed.

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Aluminum is more corrosion-resistant than steel. Aluminum is lighter than steel, but softer, so it's less of a load on your house's structure but won't take the punishment of a severe hailstorm as well as steel. Aluminum also "holds heat" better than steel; it will warm quickly in the sun, and won't cool off as fast at night. This (plus its weight) is why it's commonly used for cooking implements like frying pans. Steel is generally the opposite in all these things; stronger at a given thickness, but heavier, and even stainless steel (which is very expensive) will rust. Either of these metals will generally have a few generous coats of a very sturdy paint; for steel it is absolutely essential that the paint layer is not penetrated.

Either metal roof will be a built-in "radiant barrier", reflecting a large amount of heat away from your attic.

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