Colonial Roofs – Identifying Fence-Like Features on Colonial Roofs

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.

Since this seems to be a temporary canopy, messing around with the roof's integrity (by adding a few attachments) is probably not desirable: it will cause premature aging of the roof and increase the probability of a leak. Obviously it can be done, for example solar panels on a roof, but that adds ongoing maintenance to make sure the fastening system is rain proof.

Why not mount the frame under the eaves? Unless the roof joists are far apart, it probably isn't necessary to run a pipe across. Instead, fasten each horizontal pipe from the canopy's top to a roof joist (if they are exposed) or to a hefty screw. If the gutter is in the way, then just use some baling wire between the pipe and the screw.