Robin Talsma
7/4/2016
I'm a DIY'er and have no knowledge re: roofs/roofing etc. I have a 12x24 foot run-in shed for my horse and donkey to hang out in and get away from the flies. It's 25 yrs. old and has a shingle roof with 2' over hang all the way around. It's in dire need of a new roof and I want a metel roof on it this time and will be doing it myself. I will be taking the shingles off. The purpose of the run-in shed it to keep it cool so bugs stay out. The roof now has osb board sheathing over 2"x10" rafters with tar paper over that then the shingles. I will be tearing off the tar paper also to see what boards, if any, need replacing. The roof is not peaked. It's slanted with a 8" height at the back and a 10 or 12' height at the front of it. I have several questions. The horse and donkey hang out in here nearly all day during the bug season and a lot during bad weather. They come into a pole barn only during really really bad weather, therefore, condensation is a concern. I want the metal to be white to reflect the sun and keep it cooler inside. I have read where double sided bubble wrap is good for a vapor barrier. My friend mentioned a product called bitch-a-than(sp.???). And then, I have read re: a foam between the metal and vapor barrier? What is the foam used for (insulation?)? I have read where perlins verticle should be put down to let the condensation run thru and then perlins horizontal over those to attach the metal. Vapor barrier, foam, verticle perlins, horizontal perlins metal -- is this right? The front of the shed faces E. with a slight tilt SE. The front is the highest point of the roof. The rear is facing N. with a slight tilt NW. The cooler this shed is for my animals, the happier I will be. I get high winds and lots of snow during the winter months. Thank You for your time,
Info @windowsonwashington.net
An informed customer is our best customer.
7/4/2016
If you aren't insulating the roof, just about anything will form condensation. Underlayment on the deck will help create a vapor barrier to keep the moisture from the backside of the cold metal. Radiant barriers (i.e. reflective layers) need an air gap to work. Unless you are going to strap the roof and put down the radiant barrier first, it serves no purpose. Go with a lighter color metal and you will be rejecting much more heat than what you are currently doing.
Robin Talsma
7/4/2016
I am not insulating the roof. I was thinking of purchasing white metal roofing. So, is it best to place a vapor barrier directly on the OSB, then perlins verticle to let condensation run off, then perlins horizontal, then metal? I was not going to install a radiant barrier.
Info @windowsonwashington.net
An informed customer is our best customer.
7/5/2016
That sounds like a good plan.
Robin Talsma
7/5/2016
Thanks. I have a concern that with double height on the perlins, this might create an opportunity for wind to get underneath and rip off the metal. The back of the run-in shed faces West with a slight tile to North. This is the down side of the roof, not the up side.
Info @windowsonwashington.net
An informed customer is our best customer.
7/5/2016
Being that open to the outside, I wouldn't worry about the purlins. I would just go ahead and put down a proper underlayement over the sheathing and then install the metal.
Info @windowsonwashington.net
An informed customer is our best customer.
7/5/2016
Photo-bombed by the donkey or is he/she a mule?
Robin Talsma
7/5/2016
No, grin, he's a donkey about 14-15 yrs old, acquired from a rescue to keep the horse company. What about condensation from the horse and donkey being in there during the winter months? Maybe perlins - horizontal only? I'm going to start tearing the asphalt off next week and place Grace Ice & Water shield over the entire surface after replacing any boards that are rotted. Do I put the I.& W. shield down over the gable ends and on the front and back face boards? Thanks for your time!
Robin Talsma
7/5/2016
Also, would appreciate knowing what pitch the shed roof is when I go to order the metal. Are you able to tell by sight alone? I have no idea. Thank You.
Info @windowsonwashington.net
An informed customer is our best customer.
7/5/2016
The Grace will give you all the moisture barrier that you need. It is probably a bit overkill to be honest. Some simple woven polypropylene underlayment would do the trick. No need to really wrap the edges to be honest. As not as they are concealed by the starter and finish trim that is fine if you want to do that. Pitch is 3:12 at the most to my eye.
Robin Talsma
7/5/2016
I don't mind the overkill. I don't want to worry about this roof again. I went to my local building supply co. today for pricing and asked how to deal with the edge at the top. He didn't know. A drip edge won't do there in my mind. as the ribs on the metal will allow water to run into and down between the vapor barrier and the metal. Any suggestions? The price for a 30 x 16.5 (approx. measure with old roof still on) was $487.97, 29 guage steel painted. The ice and water shield was $371.82 and fastners (1" long) were $22.50. Total $933.09. Does this sound right? I was thinking it was going to cost well over $2,000 for materials.
Info @windowsonwashington.net
An informed customer is our best customer.
7/6/2016
If we are talking about standing seam, you can hem the seam over to close it as well as put on a piece of trim to conceal the top. Basically creating a counter flashing detail.
Guest User
7/6/2016
I don't know what standing seam is but I'm looking at just normal barn metal roofing. It has a rib on each panel put down which overlaps the rib on the last panel placed down. These with show on the upside of the roof (I don't care about it showing as much as water can get in) on the front edge as there is no ridge vent to put down. Is it appropriate to put a ridge vent there anyways?
Info @windowsonwashington.net
An informed customer is our best customer.
7/6/2016
If the space isn't to be vented, i.e. it is going direct to the deck, there is no need to vent. There are eave and ridge closures as well as metal counter flash details that are pre-made and readily available. Ask you supplier for the closures and the trim. They should have a catalog with everything you need.

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