Barn roofing

Dave H (MI)

Well-known Member
Was reading about this subject on another forum earlier in the month. We are putting in a bole building. The one topic that really gets people going with the opinions is whether to use a metal roof or traditional shingles. I like the look of shingles but was inclined to go metal because I thought it would last longer. Half the contractors quoting agree with that. The other half are pointing out that the metal roof has a lot of exposed fasteners with rubber washers on them and they say these will not last in the hot sun and that then the holes will be free to open up with expansion and contraction of the metal. This will let water in on your trusses and eventually rot them. This is a really hard choice to make.

Basically, no contractor wants to put metal on trusses with or without a barrier. The two options given are:

1) Traditional roof with a higher end shingle, light color to reflect heat, over OSB.

2) OSB roof covered with a vapor barrier, metal over the barrier. In theory if you have a bad washer water runs down the barrier I guess.

Just wondering if any barn owners could help me out. I need to make a choice this week to get on the list for the contractor.
 
I have done several metal roofs over wood and have no problems (25 years). With or without decking I use a 14ga "hat" channel __/ __ and R panel metal. Fasten the hat channel to wood with small lags or heavy screws, then fasten the roof panel to the hat with Tek screws just like you would to purlins on a metal building. Metal building suppliers have or can get hat channel. This system eliminates the roof expansion contraction from loosening the fasteners.
 
Neighbor has 3 horses in a pole barn with metal roof. Do you want me to post a pic of why metal with no insulation is really a bad idea?

Another neighbor has old metal roof, fastners are falling out, I can post a pic of that too if you like.

There are many old roofs that are rusted. Need pics of rusted roofs?

Don't ask, just look around.
 
I have a Menards building, been up for 14 years with no problems, metal over trusses. I've been inside lots of others built the same way. Use screws to hold the roof on.
 
My barn , just finished , built like just about every other agricultural building on every farm in Australia . Our summers reach 48C , almost 120F , no trouble with washers melting . Rain is probably about as wet as yours , my farm is in one of the highest rainfall areas of the state ,no rust either .
A condensation membrane/barrier is a must or else it will rain inside on humid days but otherwise there seem to be no real drawbacks .
mvphoto10458.jpg
 
I put a metal roof on my house and my shed. The roof on the house is raised seam with hidden fasteners, the shed is typical with screws.

I love the hidden fasteners/clips. Easy to install and not a hole to be seen.

Why would anyone want a shingle roof? When you consider the quality of today's singles, no way would I do it, unless code demanded it.
 
This subject gets beat around a lot.

As new materials have became available, if I were to put on a new roof today, I'd call the manufacturer to get the word "from the horse's mouth" before I began the project. Those people want your roof to last as much as you do. When I put the metal roof on my house 20 years ago, they specified screws at least an inch into solid wood. That eliminates plywood and OSB sheeting. They also specified 1/2 inch closed cell foam board under the metal. The lumber yard was not on the same page as the manufacturer of the material.

One thing I noticed - we had a local contractor who was using screws on a new metal roof, but he was driving them in with a hammer! I have no idea what was going on there, but I would have ran him off.
 
I meant to put this on Tractor Talk, as there had just recently been a post on the subject here. My mistake, but I posted it in both places and received a good amount of extremely helpful feedback. One thing is troubling me, and that is that the various contractors seem to have their own "system" of installing the roof. I had already decided to call the manufacturer(s) for their own take on these "systems" (for example, the OSB, felt, then metal) and verify it meets the standards of their warranty. You have to be really careful with contractors. Like most others you hire, they are not all cut from the same cloth. Thanks to all for the feedback. We have decided to pass on shingles and go with metal.
 
Dave - I just remembered something when you mentioned warranty - the manufacturer of the metal that I used said that the warranty on the paint was no good if you used a circular saw to cut it. The circular saw slings hot particles that damage the finish (even if you can't see the damage) and it will rust along the cut edge in a short time. I put up a metal carport roof, and used a circular saw to cut the drip edge. Sure enough - there's an inch wide band of rust along my cut edge. It's really not that hard to cross cut it with a good pair of snips, and you can score it for longitudinal cuts and snap it on the score line. Good luck with your project!
 
I built a 28' X 52' (pole)hay barn about 20 years ago, I nailed 1 X 6 sheeting lumber over the trusses and then screwed painted steel to the sheeting. I've had no problems with the roofing or the construction and condensation has never been an issue (I'm in southside Virginia).
 

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