# Almost made a huge mistake shingling a low slope roof! What materials should I use?



## Kevin993 (Jul 24, 2010)

UPDATE: Resolution reached. See my post at the bottom of the thread. Thanks for all advice given.

So I have a 12x12 "lean-to" style free standing storage shed/workshop. I just finished mold remediation on it and now I'm in the process of replacing the leaky roof. It had corrugated plastic roof panels that leaked from 3 places where the screws went through and completely rotted out most of the OSB decking. When I went up there to find out where the leak was coming from my foot starting going through the deck left and right...Had no idea it was that bad!

Anyway, I demoed the old roof, replaced all the OSB sheathing, installed #15lb felt and new drip edge flashing all around. I bought 3 tab shingles and I was going to start shingling tomorrow morning. Then reading on here and various sites I realized that the pitch of my roof is too low for shingles! Apparently the water does not run off fast enough and they won't last. It's 7' tall in the front and goes up to 8' in the back...being a 12x12 shed that makes it a 1/12 pitch roof?

Can I get away with installing these shingles on my 15# felt or should I return them to home depot and look at other options? I do not want to go the plastic route again, it already failed me once. I live in south florida so no need to work about ice and snow and such. I do need to worry about hurricanes though. I am thinking about using some sort of corrugated sheet metal roofing. Something I can use with my existing drip edge and felt I just installed as I do not want to have to redo the work. Is this the right way to go? Does home depot even sell that kind of sheet metal?

Thanks for any advice!

-Kevin


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## Kevin993 (Jul 24, 2010)

Well, looks like corrugated metal panels are out too! According to home depot they require a 3/12 slope minimum just like shingles. How is that possible they are the same? So far I cannot find any method that will work with my roof slope.


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## joecaption (Nov 30, 2011)

Got a picture?
Best thing to have done would be to redo the roof so there was some slope.
ABS is one roofing that would work with what you have, but not a great first time DIY job. Any real roofing could do a small roof like that in no time.


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## Kevin993 (Jul 24, 2010)

Hi, Thanks for your response. I will try and get a photo later but right now it just poured and the tarp on it is soaking wet. Anyway, just picture a standard lean-to, almost flat, 8 feet in the back and 7 in the front. with the 1ft overhang on each side it makes it a 12x14 roof.

EDIT:

OK So I have been reviewing all the options and most of it just seems like a huge expensive and too complicated for what I am trying to do. I have come back to the corrugated metal sheets. If I buy 10ft long sheets I can get a 6ft overlap on the down slope of the roof and I can overlap the sides by 3 corrugations.. If I also use some sort of lap sealant and butyl tape to seal off all the overlaps and joints could I possibly get away with using this metal product? It would allow me to keep my existing tar paper and drip edge and not redo my work...

Remember this is for a shed/workshop roof and I already have a great deal of time and money into it. I have looked at the rubber flat roof products, torch applied, GAF liberty, etc but they all are too big an expensive and hassle. 

Can I make the corrugated panels work?


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## shazapple (Jun 30, 2011)

Best and proper DIY option would be the modbit (GAF Liberty). You could get the corrugated metal (most places will custom order proper lengths) but it is not made for such a low slope, and will probably cost you more money in the end.


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## csab_ (Aug 16, 2011)

Kevin,

I'm in the same boat trying to reroof a patio. I haven't started the project yet, but I did order GAF Liberty in a Home Depot. It will probably arrive today. A word of advice: maybe it is worth it to shop around, because I've seen price differences in the double. I was able to get the cap sheet for $43/square in this store, but other places quoted over $80 (similar differences in the base sheet). I will only do 2-ply with MA base and the cap sheet.

There are a few things in the instructions that I'm having hard time to acquire. Home improvement stores don't seem to sell metal cap nails around here. I'll check 84 Lumber today. Another thing is asphalt primer. I could only order it on-line.

This will be my first roofing project, so I have no experience about this: but is it correct that suppliers will only sell to vendors and contractors? Because I know exactly where Home Depot is ordering their materials from, and I can find their locations on the net. It's not that I'm not willing to pay the stores' margin, but it seems like the stores stock nothing that I need and it is a major pain to go through the ordering process every single time. I'm not even sure they would be willing to order small things like metal cap nails.


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## ddawg16 (Aug 15, 2011)

Hopefully the experts will chime in but I think you want to go with something like this. They call it torchdown. It's big sheets of pretty tough rubber stuff....Buttel something....I can't remember...it's not my expertise.

This part of my roof is a 1.9:12 pitch....


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## csab_ (Aug 16, 2011)

Torch down is nice, but not great for DIY, unless you are really confident/good. I would be reluctant to work on my roof with that torch.


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## jagans (Oct 21, 2012)

shazapple said:


> Best and proper DIY option would be the modbit (GAF Liberty). You could get the corrugated metal (most places will custom order proper lengths) but it is not made for such a low slope, and will probably cost you more money in the end.


Yup, Shaz has it. Peel and stick SBS. You can also use 90# roll roofing and back nailing cement, a torch down Modified Bitumen, or EPDM, but Liberty is probably your best bet. Just make sure you screw down a proper base sheet with proper base sheet plates. Don't stick it right to the wood, you need a shear plane in there.


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## Kevin993 (Jul 24, 2010)

Hi everyone, just wanted to update you all that I have come to a resolution on this. I decided against the panels from home depot. For the number I needed and the laps I wanted it came out to $370 for JUST the panels never mind the tape, sealant, and screws. I also decided against the GAF liberty as I have read some reports about issues with the self adhering material...

I found a local roofing supplier, one of the biggest in Florida, who has a metal panel that is rated down to 1/2:12. The product is gulf coast supply PBR. They are custom making my panels right to fit my roof. Just need 4 14' long panels. They are including everything I need including sealant tape, screws, and closure strips. Best of all It is being delivered right to my door on wendsday for around $200. Can't beat that. I will update everyone when it's installed. I'm excited and relieved I figured this out. 

Thanks for the help everyone.


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## shazapple (Jun 30, 2011)

I though of mentioning the low slope hydrostatic roofs, but I thought the cost would be prohibitive. It should be noted that the instructions for the product you mentioned say 1/2 /12 is minimum for steel structures and 2/12 is minimum for wood structures.


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## Kevin993 (Jul 24, 2010)

shazapple said:


> I though of mentioning the low slope hydrostatic roofs, but I thought the cost would be prohibitive. It should be noted that the instructions for the product you mentioned say 1/2 /12 is minimum for steel structures and 2/12 is minimum for wood structures.


I noticed that too and mentioned it to the sales rep and apparently because I am using full length panels and will be sealing all the laps with butyl tape they have written approval to go down to a 1/2/12 guarantee.. They claim it is all within spec.


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## jagans (Oct 21, 2012)

I hope this system has sealant in the ribs. And don't forget the additional sealant needed at the clips, and dont forget to provide for expansion. 

IMHO You would be better off with EPDM.


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## Kevin993 (Jul 24, 2010)

jagans said:


> I hope this system has sealant in the ribs. And don't forget the additional sealant needed at the clips, and dont forget to provide for expansion.
> 
> IMHO You would be better off with EPDM.


They have provided butyl tape to seal all of the joints where the panels overlap. There are no clips that I know of it, just overlap and screw down. 

For $150 in materials cost in full length panels that are rated for my slope I would be very pleased if I got 5 years out of this roof. I suspect I will get much more though. Not to mention it will be miami dade hurricane rated once I use the proper fastener distance specifications. 

I looked into EPDM but could not locate any materials that were readily available in my area, cheap, and easy to install.


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## shazapple (Jun 30, 2011)

Sounds like an insteresting system. take some pictures when you are done!


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## LabRat0116 (Oct 2, 2010)

csab_ said:


> I'm in the same boat trying to reroof a patio. I haven't started the project yet, but I did order GAF Liberty in a Home Depot. It will probably arrive today.
> 
> I was able to get the cap sheet for $43/square in this store, but other places quoted over $80 (similar differences in the base sheet).
> 
> I will only do 2-ply with MA base and the cap sheet.


Can someone please translate this back down into layman's terms ? :whistling2:

I have a similar repair I need to do. I'm considering rubber roofing as well.



.


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## jagans (Oct 21, 2012)

LabRat0116 said:


> Can someone please translate this back down into layman's terms ? :whistling2:
> 
> I have a similar repair I need to do. I'm considering rubber roofing as well.
> 
> ...


Go to GAF's web site and download their install directions. You wouldnt make a cake without reading the box would you?

Liberty is Modified Bitumen, not rubber. "Rubber" in roof speak is EPDM.


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