Thread: Metal roof

I don't see many metal roofs around here. Saw one today with screws not only in the ridges as they should be, but also in the valley, which I wonder about. Is this alright?

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Yes, for some systems.

I believe they are supposed to be a minimum of 6" (or is it 12") up from the valley end of the panel.

I wish my Edit would work and not crash my browser.

However (this is what I wanted to add) ...

I've always seen performed valleys with the center water diverter used on metal roofing.

Attached is one detail from one manufacturer, most I have shown the same thing.

This was leaking everywhere.
It wasn't hard to figure out why.

Originally Posted by BARRY ADAIR

This was leaking everywhere.
It wasn't hard to figure out why.

Does anyone have a pdf of the manufacture installation guidelines? I am curious if the roofers should had installed the screw fasteners atop the ribs and the proper way to flash the plumbing vent in Barry's picture, as well as air vent.

Roy,

It depends on the manufacturer.

Some specify fasteners in the pan, as shown in that photo, others specify fasteners in the ribs and don't want any fasteners in the pan area (the pan area is where the water runs down, so fasteners in the pan are each a potential leakage point.

Some even have the fasteners in the ribs, except at the bottom of valleys, where they specify fasteners in the pan (to hold the pan area down tight).

When the fasteners are not in the ribs, especially the overlapping leading edge rib, be careful as the installation instructions may specify that the panels are laid from the end of the roof opposite prevailing winds, laying the panels overlapping the trailing edge, with the leading edge at the rake overlapped and protected from the prevailing winds by the rake edge.

Naturally, roofers scoff at "prevailing winds" direction and ignore such when it is specified, saying to the effect of 'show me the direction of the "prevailing winds", thinking it cannot be done.

If there is an airport nearby (within 25-50 miles or so, closer is even better), look at the direction of the main runway (or the only runway if a small airport) - those always, always, always face the direction of the prevailing wind (airplanes take off and land "into the wind", and have limited cross-wind landing capabilities). Don't know which end of the runway faces into the prevailing wind and which one faces the opposite direction, check with the airport as they will know which direction planes take off and land (also, those black marks from skidding tires landing at a no rotation and immediately having to spin up to landing speed rotation is a good indicator of which way planes land onto the runway and land into the wind going down the runway.

Most weather forecasters also know the direction of the prevailing wind.

Metal roof panels which have fasteners in every rib are likely not limited to being laid into the prevailing wind as all the edges are fastened down (some even double the number of fasteners in the overlapping edge to make sure that edge stays down in prevailing winds. The prevailing wind issue is something to think about when you see a roof fastened down in the pan area only - time to get out the installation instructions and look at Google for a nearby airport as the roof may very well have been laid from the wrong direction.

The most expensive metal roof I found laid in the wrong direction into the prevailing wind as about a $250,000 roof ... yes, that was the "roof cost" on the new construction house ... and the roof was removed and replaced, laid the correct way - a very expensive lesson for that roofer.

Sometimes, things which appear quite simple are not simple at all.