New roof - rolled aluminum or steel panel?

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A local contractor is selling a roof repair for flat-top trailers that he describes as "better than the original roof". It consists of a 2 x 2 wood frame, Styrofoam panels inside the frame, and a single piece aluminum top, wrapping over the sides of the frame. I assume the aluminum is attached to the trailer near the original drip edge. The aluminum is cut from a 13 foot wide roll, so there are no joints (trailer is 10 feet wide - an oldie).

It sounds good, but I have never heard of this before (but I have little experience). Is this an accepted practice? Any thoughts?

I did get a look at the "The Manual for ... Repair & Upgrade" (about five years old), which describes a roofing system of steel panels which clip together similar to the typical awing. This is attractive because I believe the steel is going to be more puncture resistant than the aluminum. Yet I see a problem if the original roof isn't perfectly flat. The panel will resist bending to conform to a slight curvature in the roof because of the perpendicular flanges that clip the panels together. Is this a concern?

Does anyone know where to get the clip-together roofing panels on the central coast of California?

Thanks to any thoughts on either system,
Tom

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Hi Tom,

This is a very acceptable roof over. This is the way mobile homes were re-roofed for many years before insulated panels, rubber single-ply roofing and spray foams. This is basically the same roof as the factory galvanized metal roof except it is installed over the original roof. The 2x4 frame is there to support the edges and vents and to house the panels of foam insulation. While the foam does add insulation to the roof, it's main purpose is to serve as a protective insulator between the two metal roof surfaces. This is always needed to stop metal electrolysis, but is even more important when putting aluminum over galvanized steel.

This rolled roof is often considered a "one-piece" metal roof, but it should have seams going across the roof every 3' or so. These seams are expansion seams that allow controlled expansion and contraction of the roof metal as it heats up and cools off. The mobile home roof metal is available in galvanized steel or white painted aluminum. All of the rolled roofs I have done personally have been aluminum. 4 guys can safely walk this roll up ladders and it is much easier to position once on the roof. A galvanized steel roof would require equipment (like a crane!) to get up to the roof. Aluminum won't rust on you but the down side is you have to be very careful with future recoats and maintenance. A wire brush on a 1/2" grinder can cut right through the material if you are not careful. If installed properly, you should be able to get 5 to 10 years out of the original install before needing a recoat.

This mobile home roofing material is supplied by a major distributor in your area, Holister, CA. Look for aluminum roofing materials under the products link. A contractor or distributor connected with All-Rite, can buy this roof material for much less than a DIY home owner. So it may not pay for you to do the install yourself.

I sell an insulated panel roof system ( www.centralvalleyrepair.com ) but the manufacturer does not sell the material for self install. The roofs are only sold installed. As for a product you might be able to get yourself, you might contact or google some aluminum awning companies. These are not nearly the roof product I install, but they may be a viable option for you.

Hope this helps,
JD

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Hi JD

Good info here.

Question - on a rolled aluminum roof is it noisey in the wind? Any oil canning noise?

Harry

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Hi Harry,

The aluminum re-roof will usually have less roof rumble than the original galvanized roof. A fresh install on a set home should net a pretty tight roof. Also, there will be the added insulation foam board to make it less noisy.

I have seen these roofs installed with up to 3" thick foam, adding some serious insulation quality. If a person was to use the 3" polyiso foam board (possibly layers), you could add over R-18 to the home. Polyiso from different manufacturers will have different densities and R ratings. Polyiso will also lose a small percentage of this R-value within the first few years of use.

On a side note about foam, there are different codes on the use of foam insulation in different areas, mostly due to fire concerns. Foam is very hard to ignite, so it does not increase the chance of fire. But if it does ignite, it puts off nasty chemicals in the smoke. All jurisdictions allow foam, but the type of fire retarder layer used will vary. Most times the metal roof material is sufficient.

JD