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Old 04-28-2011, 02:19 AM   #1
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Tips for a 2 in 12 pitch roof


I am going to be roofing a building that has some areas that are 2 in 12 pitch. I am going to be using comp shingles and double felt. Please share any tricks or tips for making this roof water tight.

Thanks

Dave

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Old 04-28-2011, 06:09 AM   #2
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Tips for a 2 in 12 pitch roof


2/12 is very low for composite shingles.
Ice and Water shield as an underlayment.

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Old 04-28-2011, 07:55 AM   #3
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Tips for a 2 in 12 pitch roof


To be honest, the shingles and double felt will work about as well as leaving just the plywood to fight the elements. About 6 months later, some of the plywood will be saturated. Within a year, the leaks will show inside and the plywood will be falling apart. Plan on redecking it then.

Or, you could look into SBS low slope. Match the roof color. Put down the nailable base sheet. Add one, or two inter-plies, then, the matching color granulated cap sheet.
Here's the tech stuff http://technicaldatabase.fsbp.com/do...2%7Cpid=808%5D

More http://www.mbtechnology.com/roofing-...lection-guide/

More http://www.firestonebpco.com/roofing/asphalt/sbs/

The detail work is about as complicated, or not, as shingle work.
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Old 04-28-2011, 10:18 AM   #4
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Tips for a 2 in 12 pitch roof


You guys are bumming me out :-(

I am surprised that it is not do-a-ble. A very reputable pro roofer said he could do it with shingles. I guess it could be a little steeper than 2/12 I will have to take a better measure on it today.

Thanks

Dave
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Old 04-28-2011, 02:18 PM   #5
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Tips for a 2 in 12 pitch roof


Quote:
Originally Posted by Dave K View Post
You guys are bumming me out :-(

I am surprised that it is not do-a-ble. A very reputable pro roofer said he could do it with shingles. I guess it could be a little steeper than 2/12 I will have to take a better measure on it today.

Thanks

Dave
Most dimensional/architectural shingles are spec'd down to a 2/12 with special underlayment considerations. I know some of them have abandoned the double felt spec in favor of I&WS.

I've have done this installation several times over the last 20 years and have had no problems. Is it the best solution? Probably not, but it can be done.
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Old 04-28-2011, 04:36 PM   #6
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Tips for a 2 in 12 pitch roof


I am not a roofer or play one on TV or the internet. But I've lived in a house with a 2.5 in 12 pitch for 20 years. Shingle roof. Standard felt. No leaks or problems. I'm also getting a new roof this week. (That's why I'm checking this forum) Keeping my fingers crossed.
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Old 04-28-2011, 08:04 PM   #7
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Tips for a 2 in 12 pitch roof


The roof is 2.4/12 does that help? I am torn as to what I should do. Many roofers tell me that double felt ($60.00) is all I need or I can do a ice/water layer ($300)
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Old 04-28-2011, 08:05 PM   #8
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Tips for a 2 in 12 pitch roof


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The roof is 2.4/12 does that help? I am torn as to what I should do. Many roofers tell me that double felt ($60.00) is all I need or I can do a ice/water layer ($300)

Google the brand/model of shingle you are planning on installing and read the installation instructions.

Edit: And it's half lapped felt, not double felt. They're two different things.
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Old 04-28-2011, 08:33 PM   #9
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Tips for a 2 in 12 pitch roof


I was planning on GAF timberline. Are some shingles better than others for low pitch roofs?
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Old 04-28-2011, 08:48 PM   #10
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Tips for a 2 in 12 pitch roof


If you're bound and determined, use roofing nails. HDD, not those EG felt nails. They'll be brown dust in no time.

I did it once about 11 years ago. http://rcs.si-sv2628.com/show_album_...&file=1976&s=0
I&W shield. Elks, at a 4" exposure, HDD nails. I dutch-lapped the shingles about 6" to 10", random lap widths, so there are NO joints. It's still going strong.
Old School, but the method does work.

You should also note that shingles today are NOT waterproof. Just water resistant. I've seen them leak in the center of a roof on 12/12 pitch. No holes tears, or other damage either. They just absorb water.

The ones in the pictures are undamaged in any way. 8 years old. The amount of water coming through was ruining the house. The pix were taken after a drizzly night.
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Old 04-28-2011, 09:05 PM   #11
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Tips for a 2 in 12 pitch roof


The link didn't work. Let's try again.
http://rcs.si-sv2628.com/show_album_...&file=1976&s=0

If this one is bad too, go to this one, and select 'Low Pitch Shingles
http://www.rooferscoffeeshop.com/pho..._list.asp?u=30

Steve is still getting kinks out of his site where I store albums.
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Old 04-29-2011, 05:36 AM   #12
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Tips for a 2 in 12 pitch roof


I am not a roofer or play one on TV or the internet. But I've lived in a house with a 2.5 in 12 pitch for 20 years. Shingle roof. Standard felt. No leaks or problems. I'm also getting a new roof this week. (That's why I'm checking this forum) Keeping my fingers crossed.
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Old 04-29-2011, 06:29 AM   #13
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Tips for a 2 in 12 pitch roof


Canadian Asphalt Shingle Manufacturers' Association has a nice brief on the concerns of low slope shingle applications.

http://www.iko.com/advantage/CasmaPd...lopedRoofs.PDF

You are right to be concerned about this application.
Just pay very close attention to details and don't skimp on materials.
I think I already heard you balk at $600 for Ice & Water Shield.
That's nothing when you can be confident that your roof doesn't leak.
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Old 04-29-2011, 07:41 AM   #14
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Tips for a 2 in 12 pitch roof


Quote:
Originally Posted by tinner666 View Post
If you're bound and determined, use roofing nails. HDD, not those EG felt nails. They'll be brown dust in no time.

I did it once about 11 years ago. http://rcs.si-sv2628.com/show_album_...&file=1976&s=0
I&W shield. Elks, at a 4" exposure, HDD nails. I dutch-lapped the shingles about 6" to 10", random lap widths, so there are NO joints. It's still going strong.
Old School, but the method does work.

You should also note that shingles today are NOT waterproof. Just water resistant. I've seen them leak in the center of a roof on 12/12 pitch. No holes tears, or other damage either. They just absorb water.

The ones in the pictures are undamaged in any way. 8 years old. The amount of water coming through was ruining the house. The pix were taken after a drizzly night.
I believe the wetness your referring to is a combination of condensation and side lap moisture, just guessing tho seeing as how I didn't see it in person.

I did do an experiment with GAF timberline, Tamko heritage and Certainteed landmark (controlled) and neither of the shingles allowed water to pass through.
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Old 04-29-2011, 07:48 AM   #15
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Tips for a 2 in 12 pitch roof


Quote:
Originally Posted by Dave K View Post
I am going to be roofing a building that has some areas that are 2 in 12 pitch. I am going to be using comp shingles and double felt. Please share any tricks or tips for making this roof water tight.

Thanks

Dave
The problem with low slope shingle roofs is every and any mistake during installation will result in 100's of dollars in damages later, and the later is normally just a few years or sooner.

The main thing is to find an installer (roofer) who you trust, has a proven reputation and most importantly knows your regional weather.

If it were me I would not install the shingles on any thing below a tru 3/12 with out full ice & water shield covering the entire deck (sheathing).

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