Low slope wood shed roofing


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Old 06-18-16, 07:14 AM
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Low slope wood shed roofing

I built a lean to wood shed last year with the back side of the shed against the exterior masonry wall of the main house. I used shingles for that roof.

Now I am building another shed for storage on the other side of the house and due to presence of a 4" electrical conduit running horizontally under the eave I had to reduce the slope of the shed lean to even more. To a slope about 4 inches over 1 foot.

I would like to try the peel n stick roll roofing on this shed roof. Something like this:

MFM Peel & Seal® - White - Roofing Membranes 50W36 : MFM Cart

I have several questions on using these products.

(1) It was advised in the video that I should use a primer over plywood yet I have looked at various youtube DIY videos and no one had used any primer before putting the P&S down. Is a primer necessary?

(2) Since my shed is only about 5' X 10' in dimensions, and I need to buy a minimum of 1 roll which covers 100SF, I can't use all of it. I am wondering, if I overlap more, instead of overlapping each course by the recommended amount, I overlap A LOT MORE, so I end up using most of it, will that improve the performance any? Or just plain stupid?

(3) I wonder how easy it is to do the unroll and peel application. I can see if you have a flat roof with one guy rolling and the other guy walking backwards slowly...but the shed is only 10' long. The other guy would back three steps and be falling off. I might have to do this all by myself...if it creases and go "off course" can I pull it off a little and adjust, or once it sticks it sticks?

(4) Last question regarding drip edges. The front drip edge goes on first, then the peel and seal roll roofing, then the two sides drip edges right over the roof roofing right? On the two sides, what kind of fasteners should I use? Should I use these?



Thanks in advance!
 
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Old 06-18-16, 07:41 AM
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Well I know you get more annual rain than we do, but if your slope is really 4" per foot, a 4:12 pitch is a good amount of pitch for a shingle roof, and I don't see any reason why you would need to take any extra measures at all. 4:12 is not low slope... less than 4:12 is. You can use shingles and don't need to use roll roofing. Roll roofing sucks and should only be used on something that is actually low slope (like on a 2:12 roof). There are houses here that have 2:12 pitch and they have shingles. Not that i recommend it, but they dont leak. Most will lap the felt paper farther just in case. A 2:12 shingled roof is more likely to leak if there is an ice dam. I doubt ice dams are a problem in Florida. Lol

No one around here uses primer, but I have also seen the ice and water shield separate during high wind when left uncovered for an extended period of time. That's why primer us recommended, and I'd probably even more critical if a hurricane blows off the roofing and you still hope to have some protection. (Assuming the sheathing doesn't blow off with it!)

The suggested overlap is simply a minimum. Overlap it all you want.

Most peel and sticks will have a backing that has a seam, or a pull cord to rip the backing into halves. If working by yourself, you can lay it out... fold it over onto itself (the long way... turning a 3 x 10 into a 1 1/2 x 10), remove half of the backing, stick that half down, the fold the other half over, remove that backing, then stick that half down. Once it sticks, it sticks.

Technically, most mfg's will say their product must be fully adhered to the sheathing itself... not on top of any flashing. And your flashing would be held by roofing nails, not neoprene washer screws (barn screws).
 
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Old 06-18-16, 09:16 AM
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The run of the mill subdivision houses that I painted in fla had a 4/12 pitch.

The screws you pictured are normally used on metal roofing, as X said, you'd use roofing nails so the head is flush with the underside of the shingles or rolled roofing.
 
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Old 06-18-16, 10:11 AM
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Yes we have a lot of rain in the summer and the summers last like 10 months LOL.

As far as leaks and water penetration I am not that worried. It's a wood shed and it's not meant to be fully air and water tight. I used 3/4" marine grade plywood on the roof deck and it is screwed down with 2.5" deck screws onto the 2X4 rafters. It will probably be blown off in a cat 3 hurricane.

As far as the flash metal, what I did with the shingles was I nailed them down with roofing nails on the sides and front, then the membrane and shingles over it. However, after I did that I read somewhere else this is not the right way. The article I read said the front edge should be nailed down first (using roofing nails). Then the waterproofing membrane over the entire area. Then the metal for the two sides go on top of the membrane (with roofing nails), then finally the shingles go over the whole thing. This means the front metal is tucked under the membrane and shingles, but the side metal is tucked BETWEEN the membrane and shingles. So my question is, with these peel and stick roofing - does that mean I should apply the SIDE metal over but not under the membrane? If that is the case then I need something besides roofing nails since they would be exposed to the element. Unless the article I read is wrong about this.
 

Last edited by MiamiCuse; 06-18-16 at 10:32 AM.
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Old 06-18-16, 10:22 AM
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Like I said, all the major ice and water shield mfg's do not say to put it over any flashing... not even the bottom one. But do it however you want. Some argue either way.

Here is an example: https://www.google.com/url?sa=t&sour...tB-fUANNLAKplQ

It says to apply metal flashing on top of the membrane. I don't understand your problem with roofing nails.
 
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Old 06-18-16, 10:43 AM
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The best thing to do to satisfy both the mfg instructions and the desire that most people naturally have... to put the ice and water shield down over the top of the bottom drip edge... is to first apply an 8-12" wide strip of ice and water shield across the length of the roof, then cover that with the drip edge, then cover that flashing along with the rest of the roof with the ice and water shield. Then apply the gable end drip edge on top of that.

Ice & water UNDER or OVER the drip edge? | GreenBuildingAdvisor.com
 
 

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