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Low Slope Roof question


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I live in the western NY. My roof needs replacing.

Background: My porch roof has a slope of 2.75" per foot and is attached to two adjacent roofs through shingles that are weaved. Ice and water shield was laid down about 7 - 8 years ago, about 5 - 6' back I believe. The roof itself is approx 30 feet in length and 12 ' deep in one area, maybe 30' deep in another. The soffits do not appear to be open (I am not sure). The area is vented with two vents at the peak. There is insulation in the area but not much. The roof gets an ice dam where the two of the roof abut near the eaves. Ice also forms on top of the gutter toppers we had installed. The gutter toppers were installed in such a way that the roof rather flattens out more near the eave and, of course ice forms.

Question: I've received a variety of suggestions about how to roof this area so that it won't leak. The leak is generally contained to the ice dam where it abuts . Are shingles or architectural shingles appropriate for a roof with this slope? Is there a better material or way of doing it? Should we first remove the gutter toppers and see if that makes a difference in the issue?

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A roof at that pitch should have 100% ice and water shield underlayment - not just 6' from the eaves. Read the manufacturer's instructions.

Mike,

Normal shingles on top? or architectural shingles?

Is there any point in more than one layer of I/W shield?

- MK

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The shingle type is basically irrelevant if you lay ice & water shield across 100% of the substrate. The shingles do need to be installed, but their primary job in this configuration is going to be to protect the ice & water shield from UV. If the first layer of ice & water shield is installed correctly, there is no need for a double layer. But then again it wouldn't hurt anything and I would probably put it on my roof.

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Originally posted by beagle150

A roof at that pitch should have 100% ice and water shield underlayment - not just 6' from the eaves. Read the manufacturer's instructions.

Mike,

Normal shingles on top? or architectural shingles?

Is there any point in more than one layer of I/W shield?

- MK

Cary is right, the type is irrelevant. It sounds like you think that by 100% of the surface you thought I meant 100% of the roof the first 6ft. from the eaves, which is not what I meant. The entire surface of the roof is supposed to have a layer of ice and water shield on it when you install a comp shake at that pitch.

Something else I should have mentioned; a comp shingle at that pitch should also only have a 3inch reveal; not the typical 5inch reveal.

Hell, even Malarkay, which makes composition roofs out of modbit that are specifically designed for a low pitch application, requires the entire roof to be covered with ice and water shield.

The bottom line is that the roofer screwed up. Did he even bother to install drip edging?

ONE TEAM - ONE FIGHT!!!

Mike

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Use best grade ice & water shield. Get the WR Grace.

Wrap it down behind the gutter and all the way to the peak.

Think long and hard how to ventilate. Grace keeps all the water out, but it also keeps all the water in.

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Originally posted by kurt

Think long and hard how to ventilate. Grace keeps all the water out, but it also keeps all the water in.

Kurt and all,

Yes, ventilation is an issue.

The soffits don't appear to be open and the crawl space is not easy to get to (no access). The only ventilation are two "box" vents (not sure what kind they are) that sit just below the ridge line (where two roofs meet). This though is the top of the 30' deep area .... most of the rest of the roof is only about 12 feet deep and buts up against the house.

I appreciate everyone's comments, I had previously thought I would not be able to have this part of the house shingled.

- MK

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The shingle type is basically irrelevant if you lay ice & water shield across 100% of the substrate.

Has ice and water shield withstood the test of time in your areas that have ice damming issues? I just installed it on a roof I am working on, and am just curious.

Something else I should have mentioned; a comp shingle at that pitch should also only have a 3inch reveal; not the typical 5inch reveal.

Mike,

I don't disagree with you on that matter, especially if 3 tab shingles are not used (more of a blow off issue). Are there some shingle manufacturers out there that do allow a 3 inch reveal? I just want to read their instructions, etc.

Also, as far as I am concerned they should quit manufacturing 3 tab altogether.

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Originally posted by Brandon Whitmore

The shingle type is basically irrelevant if you lay ice & water shield across 100% of the substrate.

Has ice and water shield withstood the test of time in your areas that have ice damming issues? I just installed it on a roof I am working on, and am just curious.

Something else I should have mentioned; a comp shingle at that pitch should also only have a 3inch reveal; not the typical 5inch reveal.

Mike,

I don't disagree with you on that matter, especially if 3 tab shingles are not used (more of a blow off issue). Are there some shingle manufacturers out there that do allow a 3 inch reveal? I just want to read their instructions, etc.

Also, as far as I am concerned they should quit manufacturing 3 tab altogether.

Dunno,

I was weaned on 3-tab and my father taught me to reduce to a 3-inch reveal for anything between 2:12 and 4:12 and never to use comp for anything under 2:12. Decades later, that's also what I was taught when I went through the "training" provided by the franchise outfit I used to be with.

The old man marked off with a story stick from the eaves, snapped lines, and then used 3-inch or 5-inch shingle gauges made from a piece of furring to make sure that every shingle was properly positioned.

ONE TEAM - ONE FIGHT!!!

Mike

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The old man marked off with a story stick from the eaves, snapped lines, and then used 3-inch or 5-inch shingle gauges made from a piece of furring to make sure that every shingle was properly positioned.

This may sound kind of sad, but I've never hand nailed a roof. I just use the gauge on the gun. I can't tell you the last time I snapped a line either, just use the ones on the paper. [:-paperba

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Has ice and water shield withstood the test of time in your areas that have ice damming issues? I just installed it on a roof I am working on, and am just curious.

Yes, it holds up just fine in WNY. It has been the norm on new construction for at least the last 20 years.

As for the ice dam issue, ventilation may help, it may not. I have seen complicated roofs that won't vent well at all, and some very large roofs that are ice machines even with full soffit and ridge vent. Ventilation has to be designed for the roof, there is no one size fits all solution.

If I were going to contract a roofer in WNY it would be Neth and Sons. They are very up to date on residential and comercial roofing products and have done urethane part conditioned retrofits in the area (insulating the roof deck instead of venting). They will not be the cheapest, but a cheap roof is a bad idea.

Tom

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