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longfisher 05-15-2013 04:40 PM

Jagans - Help - Low Slope Shed Roof - LDPM
 
1 Attachment(s)
Jagans,

I don't mean to diminish other roofing pros here, but I've been lurking here for a while before registering and I think you might be the one to answer my questions about LDPM.

Here's a pic of an 8 X 12 low slope (0.5" / 12") shed I had to take the previous A-frame roof off of due to HOA. Now, I need to properly roof this nearly-flat roof. The roof is 3/4 plywood and is not covered with just felt paper to protect it while I decide on a roofing material.

I live in Spring, TX, just north of Houston. We have lots of hurricanes here, high winds (up to 50 mph) with periodic thunderstorms and plenty of rain (average 36 inches a year).

I think EDPM is the way to go and I've been reading some of your posts about this. But I have a problem in that the major suppliers of EDPM materials in that they seem to concentrate on commercial suppliers or they don't want to spend time with a DIYer or they want to sell me much more materials, especially membrane, than I need for this small project.

Also, I believe that this should be a fully adhered membrane job but I've read several posters (including you, I think) where an underlayment was recommended instead.

Would you mind commenting on this project, please? Also, anyone else who has experience in this sort of project is, of course, invited to chime in.

Best,

David

MTN REMODEL LLC 05-15-2013 06:16 PM

Jagans will have the answere.... but a question.... does appearance/aesthetics matter... can't be sure from your pic.

longfisher 05-15-2013 07:16 PM

Quote:

Originally Posted by MTN REMODEL LLC (Post 1180152)
Jagans will have the answere.... but a question.... does appearance/aesthetics matter... can't be sure from your pic.

Well, I surely don't mind the politely phrased criticism.

It was to be an A-frame. I'm sure it' would've looked better if it was.

Also, it's not quite finished and not painted yet. Some of the trim and even some planking near the top had to be removed to accommodate the revised flat roof.

Anyway, it was a funny questions and an astute observation. I got a laugh out of it.

With your permission I'll post a pic when it's done. Of course, you're invited to be as frank and funny then as now.

Best,

David

MTN REMODEL LLC 05-15-2013 07:31 PM

Quote:

Originally Posted by longfisher (Post 1180192)
Well, I surely don't mind the politely phrased criticism.

It was to be an A-frame. I'm sure it' would've looked better if it was.

Also, it's not quite finished and not painted yet. Some of the trim and even some planking near the top had to be removed to accommodate the revised flat roof.

Anyway, it was a funny questions and an astute observation. I got a laugh out of it.

With your permission I'll post a pic when it's done. Of course, you're invited to be as frank and funny then as now.

Best,

David

David..... Actually I'm not sure if you're puttin me on... if you are ... ya got me.

But I think the shed looks fine ....and my question was meant to mean, do you care what the roofinjg looks like. (ie do you or neighbors look down on it... at .5/12 no one is going to see it from the ground.... from your picture which is looking down, I couldn't tell if you were on a deck where appearence might count, or on a roof and wouldn't care about appearance.)

I'm in Co snow country, so no low slopes around here and little experience. But my son and I just had a "hot mop" put on in his Socal 1/12 roofed home.

It gets covered with pebble/stone (varios colors) and does give an aesthetic effect if desired. I have no idea of its performance or if even it's done in your area.

Best Regards

Peter

Oh... by the way... your lawn needs cutting.. LOL

longfisher 05-15-2013 07:35 PM

Not putting you on.
 
Actually, the pic is from my second story and the neighbors really cannot see the shed well because of the realtively well-spaced lots and the foliage.

Thanks,

David

jagans 05-15-2013 08:23 PM

Well, I am indeed flattered that you would request me directly. Thank You.

First of all, lets call it the right thing so the commercial roofing suppliers don't laugh at you. It is EPDM or Ethylene Propylene Diene Monomer. It has actually been a Terpolymer for a long time, but the name of EPDM has stuck. Dont feel bad, most of the people that sell the stuff don't call it the right thing, and I have an Architect friend who calls it EDPM, and I have given up trying to correct him.

As far as installation goes, I agree with your installing the membrane fully adhered. You should use a recovery board over the plywood, under the membrane. The reason is that wood moves too much, and the chance of nails backing out and protruding through the membrane is high without a recovery board. Screw down High Density Fiberboard with 3 inch metal insulation plates designed for hard insulation with No. 14 SD screws, at 1 fastener per 2 square feet, and you will be fine. Fully adhere 60 mil unreinforced membrane to the recovery board. You should be able to do this roof in one piece with no seams. Install nailer around the perimeter that matches the thickness of your recovery board, and turn the membrane over and down the outside, and install a minimum .040 Aluminum gravel stop on three sides and a drip edge on the low side. Caulk the laps with urethane sealant, but do not nail through the laps. Nail about 4 inches on center, staggered but not more than 1 inch from the edge of the flange. Brush the metal flange with quickprime plus, and strip the metal in with quickseam flashing tape.

Contact a local commercial roofer that does single ply, and tell him you have a small shed to roof and you would like to buy some EPDM and accessories from him to do the work yourself. They will have as much as you need as left overs in the shed. Commercial Roofers are really very nice people for the most part, and will generally go out of their way to help you. If you run into a gruff one, try another.

Were I you, I would roll on two coats of white acrylic when you are done. Firestones Acryltop is great stuff, and you can have HD tint it for you if you want. It will keep movement to a minimum, and keep UV off the membrane. Your roof will last for a very long time.

Good Luck to you.

tinner666 05-16-2013 06:43 AM

2 Attachment(s)
Jagans has good advice. :thumbsup: Now, I'll confuse you.:)

I'll offer a little clarification about one thing, or two.
"Screw down High Density Fiberboard with 3 inch metal insulation plates designed for hard insulation with No. 14 SD screws, at 1 fastener per 2 square feet, and you will be fine. Fully adhere 60 mil unreinforced membrane to the recovery board. You should be able to do this roof in one piece with no seams. Install nailer around the perimeter that matches the thickness of your recovery board, and turn the membrane over and down the outside, and"
Install the nailer first, not after the insulation.
Things I do. I extend the nailer over the fascia and rakes 1/2" or more to allow for clearance for siding, hanging a gutter behind it, etc.
Before drip edge became common, it was common to extend the decking 3/4" past fascias to create a builtin drip edge. Water wasn't able to get behind the fascia when done this way. Buildiing it flush with fascia keads to all kinds of problems with water wicking, inability to prperly hang gutter, flash an area, and water will follow the DE right into the fascia.

My preference is to use 1 x 8" nailer and 1" ISO insulation. When I put the cover tape on the drip-edge, the hump that it creates to hold water is eliminated.

jagans 05-16-2013 12:51 PM

Quote:

Originally Posted by tinner666 (Post 1180421)
Jagans has good advice. :thumbsup: Now, I'll confuse you.:)

I'll offer a little clarification about one thing, or two.
"Screw down High Density Fiberboard with 3 inch metal insulation plates designed for hard insulation with No. 14 SD screws, at 1 fastener per 2 square feet, and you will be fine. Fully adhere 60 mil unreinforced membrane to the recovery board. You should be able to do this roof in one piece with no seams. Install nailer around the perimeter that matches the thickness of your recovery board, and turn the membrane over and down the outside, and"
Install the nailer first, not after the insulation.
Things I do. I extend the nailer over the fascia and rakes 1/2" or more to allow for clearance for siding, hanging a gutter behind it, etc.
Before drip edge became common, it was common to extend the decking 3/4" past fascias to create a builtin drip edge. Water wasn't able to get behind the fascia when done this way. Buildiing it flush with fascia keads to all kinds of problems with water wicking, inability to prperly hang gutter, flash an area, and water will follow the DE right into the fascia.

My preference is to use 1 x 8" nailer and 1" ISO insulation. When I put the cover tape on the drip-edge, the hump that it creates to hold water is eliminated.

Hi Tinner. Glad you are well.

I do not use iso any thinner than 1.5 inches thick, as I have had some pretty bad dimensional stability problems with 1 inch material, also, the strength of the bond between the foam and the black facer is not very good compared to the internal bond strength of HD fiberboard, which is a homogenous product. He said he had some high winds. Installing a high R product like iso also holds the heat in the membrane, which accelerates aging. You are quite right in providing a break down at the drip nailer, but it looked like he had pretty good slope and being in Texas, I figured evaporation would take care of any residual water at the stripping plies/ drip edge. He could probably use a cementitious type of board to serve as a heat sink but then you have the problem of the plates sticking up. I did not want to over complicate things on such a small roof.

I actually use a 18 inch tapered edge to accomplish just what you are referring to on most commercial projects. I cut the toe off at the nailer. Good Advice.

tinner666 05-16-2013 01:52 PM

Thanks for the tip on the 1-1/2" stuff. Some around here use 1/2" ISo or recovery. I don't care for the recovery board.
All my jobs are resi and 1" is about all I can add to a deck due to siding, window, valley and other considerations I keep running into.
You advice is spot on.

jagans 05-17-2013 07:04 PM

Oh I forgot to mention, I would think that you should probably be using fire retardant membrane with residential work. You may want to look into this vis-a-vis homeowners insurance. :whistling2:

tinner666 05-17-2013 10:40 PM

Quote:

Originally Posted by jagans (Post 1181477)
Oh I forgot to mention, I would think that you should probably be using fire retardant membrane with residential work. You may want to look into this vis-a-vis homeowners insurance. :whistling2:

:yes: It's the ONLY thing I spec. Lots of idiots running around here low bidding reg .045. Not me.:)

jagans 05-18-2013 09:48 AM

Quote:

Originally Posted by tinner666 (Post 1181665)
:yes: It's the ONLY thing I spec. Lots of idiots running around here low bidding reg .045. Not me.:)

Man you are a real Fart Smeller, er....... I mean Smart Feller! :thumbup:


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