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Metal Roofing Repair Disaster! Help!

reamick's picture

I've moved back to my parents' 60-ish year old farm house that has had pretty much no maintenance or repairs done on it.  Several years ago, my Dad installed a metal roof over ashphalt shingles.  After he put the new roof down, he decided to add some vents (there weren't any there to start with).  He chopped a hole in the roof, and screwed the vent over top, and dressed liberally with tar.  As it leaked, he added more tar.  He gave any other transition areas (the electrical mast, the plumbing vent...) the same treatment. 

Before I begin any plaster repair and painting, I want to get this fixed properly.  But after a lot of research, I'm still stymied as to the best way to put a vent in a metal roof, never mind a retroactive repair like this one.

Can anyone out there offer me some advice on how best to deal with this?





Eternabond roof seal tape (post #206518, reply #1 of 6)

Eternabond roof seal tape worked for me.  It was used on low slope roll roofing roof a few years ago, and still holding up well.  Also on metal roof vents.

The tar on the flashing in probably over the nail heads?  Even if the seal looks broken, there wouldn't be enough leak to worry about.  If you want to make it better, squeeze some polymer caulk (quad) under the flashing over the hole and renail then smear some caulk over the head.

It was a mistake (post #206518, reply #2 of 6)

to put metal roofing over asphalt. As the metal expands and contracts in the heat, the granules on the asphalt are grinding off the coating on the bottom of the metal and helping it rust. Oh well...

Those vents are not designed to be installed on metal, at least not easily. The best method IMO is to build a small curb (like a skylight), flash it, and then install the vent on top of it. Trouble is, there probably is not enough metal around the edges of the vent to bend down over the curb the way you'd want to, so you'd need some skill with sheet metal to make it work. A good metal roofer could do it but would likely comment on how it's not really supposed to happen. There may be vents that would work better, but it could take some trips to roofing wholesalers to find out.

Second best is to slit the metal roofing panel(s) and tuck the top half of the vent in under the roofing above it. You probably won't find any roofing manufacturer to recommend it, though it's better than what you have.

What would happen if you simply eliminated the vent(s) and replaced the panels? Does the attic need 'em?

>>>Does the attic need (post #206518, reply #3 of 6)

>>>Does the attic need 'em?

Zackly what I was thinking.

If the attic needs venting then you'd be much better off with "real" attic vents like the turbine type. Consider paying a pro roofer to remove the existing vents and replace, with proper methods, with a turbine type. It's a pretty small job (maybe half a day for one or two vents I'm guessing) and shouldn't cost a whole lot.

Thanks for all the help guys! (post #206518, reply #5 of 6)

Thanks for all the help guys!  There's 4 of these chopped in the roof right now.  I was wondering if the vents were really necessary, or if there was another way around them.  The house is actually 1 3/4 stories, so only a part of the sloped roof is over unheated space.  Maybe I can figure a way to weasel the venting and not chop the roof.

Thanks again,



Michelle, (post #206518, reply #4 of 6)

This is an easy fix except for the tar. Clean that up first.  Get another sheet of metal in the same profile (SM Panel?) and run it from the ridge to the bottom of the vent, notch out for the vent. Just like you would do with shingles. Use some closures at the to of the vent and caulk the sides with Lexel.



  I think you should (post #206518, reply #6 of 6)


I think you should contact a metal roofing contractor to solve your problem. As you said that your roof is very old so you need to take care at the time of repairing. So in my point of view to avoid any kind of mistake or problem you should hire a contractor as your roof needs lots of work.

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