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  • Aug 8th, 2019 4:26 pm
[OP]
Deal Addict
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Apr 25, 2011
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Saint-Eustache

Roofing question

I have a Gazebo and planning to change the asphalt shingle.

Should I install Weathertex self adhesive membrane or underlayment is enough?

Thanks.
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10 replies
Deal Guru
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Feb 11, 2007
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Oakville
Rlcky wrote:
Aug 6th, 2019 3:22 pm
I have a Gazebo and planning to change the asphalt shingle.

Should I install Weathertex self adhesive membrane or underlayment is enough?

Thanks.
I just put tar felt underlayment under my shingles when I did my shed.
Deal Guru
Jan 27, 2006
11297 posts
4609 upvotes
Vancouver, BC
Realistically, for the difference in cost for such a small area, I would actually use the higher end stuff and do it once. Sure it will cost a few bucks more but the time and effort you are using far outweigh the difference in cost for the material.
Deal Expert
Aug 2, 2001
15924 posts
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You'll be fine with either. Because it's not a heated area I am not sure that ice will be forming, which means ice and water shield is not needed. Seems like overkill to me.

That said, one thing to keep in mind is that you can easily buy a roll of tar paper for $30-40. But to buy a roll of ice/water shield might be much more for the smallest rolls they offer - so on such a small job it might make a difference in terms of overall cost.
Member
Oct 22, 2016
221 posts
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Comox Valley
In most cases, just felt paper.
However if slope is low, the membrane might be a better choice.
[OP]
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Apr 25, 2011
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Saint-Eustache
User452441 wrote:
Aug 6th, 2019 10:57 pm
In most cases, just felt paper.
However if slope is low, the membrane might be a better choice.
what a difference between the membrane and felt paper?
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Deal Addict
Nov 17, 2012
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Toronto
When I shingled my detached 12x20 garage, I stripped the old crap off down to the 80 year old plank roofing, replaced a rotted section with plywood and covered the entire thing with ice/water shield and then shingles.

I figured why not. Cost maybe $100 or something at the time and more or less guarantees no leaks. That being said, I'm not sure if it will make ripping the shingles off again easier, or harder. I expect if I do it on a cool day, there will be less chance of tearing up the adhesive membrane. Did this 17 years ago and some of the shingles that get south sun exposure are curling. Nice thing is with the membrane, the shingles are just protective and cosmetic. I don't really rely on them for water protection.
Deal Addict
Jan 21, 2018
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Vancouver
Felt paper is cheap, but aside from ultra-low cost I don't know why anyone uses it these days when synthetic underlay is so much better. The synthetic is tougher, more durable over time, comes in wider rolls for quicker and easier coverage because it's much lighter in weight, and it's ok to have a little rain while it's exposed during installation. Felt paper is very heavy, comes in narrower rolls because of the weight, and tears easily if anything damages the roof (like animals).
Member
Oct 22, 2016
221 posts
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Comox Valley
Rlcky wrote:
Aug 8th, 2019 8:36 am
what a difference between the membrane and felt paper?
Above 2 post covered it well. There is #15 felt, #30 felt, ice and water shield (membrane)
For years #15 felt, and #30 felt was used on the roofs. #30 felt at eaves and in valleys, and then #15 felt over the rest of the roof.
synthetic underlay, is a better product than the above felt.

On the west coast, some roofers will use a #30 felt at the eaves, and valleys, then synthetic underlay over rest of roof. Reason for the #30 felt is to go with code, I am not aware of a synthetic underlay, at the eaves that can meet this requirement. If I am mistaken please correct me.

For the ice and water shield (membrane), in the Vancouver area is not used often (4/12 slope and above), due to the winters we have. In the rest of Canada, I agree in using it at eaves and valleys. I have only seen one ice damming problem in the Lower Mainland in 30 years. Sucks if it is you though.

However we I talk about slope, if your slope of roof is below a 4/12, ice and water should be spec for it. The reason for this, is the slope is that low, that water can get in more easily, and the ice and water will help stop it. Be aware that no shingles should go below a 2/12 slope.
[OP]
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Apr 25, 2011
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User452441 wrote:
Aug 8th, 2019 12:29 pm
Above 2 post covered it well. There is #15 felt, #30 felt, ice and water shield (membrane)
For years #15 felt, and #30 felt was used on the roofs. #30 felt at eaves and in valleys, and then #15 felt over the rest of the roof.
synthetic underlay, is a better product than the above felt.

On the west coast, some roofers will use a #30 felt at the eaves, and valleys, then synthetic underlay over rest of roof. Reason for the #30 felt is to go with code, I am not aware of a synthetic underlay, at the eaves that can meet this requirement. If I am mistaken please correct me.

For the ice and water shield (membrane), in the Vancouver area is not used often (4/12 slope and above), due to the winters we have. In the rest of Canada, I agree in using it at eaves and valleys. I have only seen one ice damming problem in the Lower Mainland in 30 years. Sucks if it is you though.

However we I talk about slope, if your slope of roof is below a 4/12, ice and water should be spec for it. The reason for this, is the slope is that low, that water can get in more easily, and the ice and water will help stop it. Be aware that no shingles should go below a 2/12 slope.
As i'm doing my Gazebo and small area, doesn't it bother instead of using felt paper or synthetic underlay and to use weathertex eave protection all over?
Rogers Unlimited Province, 7gb $39/month! Thanks RFD!!
Member
Oct 22, 2016
221 posts
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Comox Valley
Rlcky wrote:
Aug 8th, 2019 3:01 pm
As i'm doing my Gazebo and small area, doesn't it bother instead of using felt paper or synthetic underlay and to use weathertex eave protection all over?
Absolutely that will be fine to use weathertex all over. No concerns with that.

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