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When do people use 15# paper

11K views 31 replies 6 participants last post by  RooferJim 
#1 ·
Is it the standard to use 15 or 30# tar paper? I was planning on using double underlayment with 30# paper. Is this overkill? The roof doesn't have a steep pitch that is the reason for double underlayment.
 
#2 ·
the few roofers i've talked to say they always use 30# after being burned by using the 15# once in the past. you might even need it to validate the shingle's 20-30year warranty

I imagine there isn't much price difference... and is there really such a thing as over-kill, especially when it's your own roof (is it?)

you don't want to be tearing up the thin stuff as you walk around too...
 
#3 ·
I prefer 30#, but most recomendations are for a 15# due to less wrinkling potential.

I tarp up our roofs every night, so moisture infiltration and the resultant drying out and wrinkling never becomes an issue.

Steeper roofs, a 30# is the recommended choice.

These are the manufacturers and NRCA "Recommendations", not requirements. I prefer to always exceed the "Minimum" requirements mandated in just about every phase of the roof possible.

A flat and tightly installed double layer of 15# is probably better than a single layer of 30#, but at what point do you create the gold plated pig, which will not be cost effective and be able to sell?

Ed
 
#5 ·
On a 4/12 pitch, that would be a good idea.

A better idea, as long as 100 % continuous soffit intake and 100 % ridge exhaust ventilation specifications are followed, would be to do a 100 % coverage with Grace Ice and Water Shield protective underlayment.

If you want to know the correct amount ov intake and exhaust ventilation you need, provide the exact measurements of the house and the amount of soffit overhang extending past the walls.

The shadow cast down from the outline of the entire roof structure, would be called its "Footprint". That would be the most helpful for the correct answer.

Ed
 
#8 ·
Your state is following the OLD NRCA guidelines. Recent additions more properly address utilizing Ice and Water Shield for the pitces between 2/12 and 4/12.

Ed
 
#10 ·
I haven't see anybody use ice and water shield in my area. Is this stuff expensive? Do you just use it for the first run then use felt? There is no ice or snow in my location. It will cost me about $120 extra to lay down two layers of felt. Would I just be throwing my money away?
 
#12 ·
It does sound interesting. I was a referring to two ply felt being a waste of money. Would this be a waste of money compared to just using a single layer? The cost difference between 2 layers would be $120. In total I would be buying 12 rolls of 30# for double felt. How much would it cost for 22 to 25 squares of ice and water shield? Any special codes involved with this stuff or is it considered felt (follow same application procedures)?
 
#13 ·
Well its a little different. it has an adheasive on the back and sticks. that is what makes it good. a roofer can put it down just as easy as felt but maybee not so with a DIY or some carpenters. it is more money but its worth it. I buy the stuff by the pallett so Im sure you would pay a bit more. You best bet is to check out a roll at a suppy house. Its like buying insurance on your roof.

RooferJim
www.jbennetteroofing.com
 
#14 ·
Well its a little different. it has an adheasive on the back and sticks. that is what makes it good. a roofer can put it down just as easy as felt but maybee not so with a DIY or some carpenters. it is more money but its worth it. I buy the stuff by the pallett so Im sure you would pay a bit more. You best bet is to check out a roll at a suppy house. Its like buying insurance on your roof.

RooferJim
www.jbennetteroofing.com
My brother is a roofer in the Seattle area where it rains all the time and they put that stuff down and then leave for months to do other jobs then come back and roofs later. They are so busy he told me that is the norm and he has never had a problem. We are talking commercial buildings with hundreds of squares for one job. The stuff really works.
 
#15 ·
I am planning on using double underlayment, but I do not want wrinkles. I will be applying the shingles right after the underlayment is applied. Will I have problems later with double 30# wrinkling and buckling the shingles? I can use 15# if this will be a problem. I am currently looking into gracie ice and water, but it seems like it is 5 times the cost of 30#.
 
#17 ·
Argh!! remind me not to use his company!!!

Unless somebody has a good excuse, like Katrina hit, no contractor who is worth a dime is going to start a job, expose the roof deck, and leave for months.. Even if they use deck armor. Ice and Water, in the GAF Weatherwatch brand, doesn't allow unlimited exposure. I think it is between 30 and 60 days max.


Iquote=warnerww;48692]My brother is a roofer in the Seattle area where it rains all the time and they put that stuff down and then leave for months to do other jobs then come back and roofs later. They are so busy he told me that is the norm and he has never had a problem. We are talking commercial buildings with hundreds of squares for one job. The stuff really works.[/quote]
 
#18 ·
That is they way it is. These guys do not even advertise. Their is no way to get a hold of them other than word of mouth. They are not in the yellow pages they do not advertise at all. They are considered the best of the best. They will not even look at hiring you unless you have been on the roof for at least 10 years. These guys know their stuff and get paid for it. They work hard but the actually get 4 days paid vacation which if you are a roofer you Know how rare that is. At least that is rare in my experience. Most construction people work and get paid or do not work and do not get paid.
 
#19 ·
OK

I will look into other products. I also want to give my local building inspector a call before using it. I just don't want any surprises. How about using double 30# paper? This stuff is pretty thick. Do you think it has the possibility of pushing up the shingles?
 
#21 · (Edited)
The pitch is 4 in 12. I guess that would be considered a low pitch. I am definitely going to use ice and water in the valleys and where I think a leak may occur. I'm just want to explore my options. I'll get some prices on other ice and water products today. The only thing that appears to be a turn off to 100 percent ice and water is condensation issues/ breathing issues. I am planning on running a ridge vent across the entire roof with 100 percent soffits, so I'm guessing ventilation will not be an issue. Another issue is removing the ice and water for the next replacement. I know that it is impossible to remove. I don't know how the building inspector will handle the situation when a reroof is necessary in 20 years. Sheathing inspections are required in my area.
 
#22 ·
If it is installed correctly, does not leak, and has 100 % balanced intake and exhaust ventilation as you stated, unless the decking is already starting to show signs of delamination and feel crunchy to walk on, 20 years from now, it will still be in good shape.

Put the felt paper over the top of the Ice and Water Shield if you are concerned about the shingle sticking to it during the next tear-off 20 + years down the road.

Ed
 
#25 ·
RooferJim,

Do you get it right from the Cetainteed wharehouse for that price?

That seems incredibly inexpensive.

Regarding I & W shield. Which one do you guys prefer. I have always been a Grace Vycor Plus user, but the cost runs between $ 82.00 to $ 91.00 per 67.667 foot roll from 2 of my suppliers, being only 2 squares.

P.S. I charge $ 3.00 per lineal foot or $ 1.00 per square foot for it. Is that in your guys ballpark. It doesn't seem too expensive in my opinion, but I am getting way undercut this year, by everybody!!!

Too many illegal subcontractors flooding the market-place in the Chicago area going completely unchecked.

Ed
 
#26 ·
At $45 a square ($90 for two square roll). I'm looking at $1080 to do the whole house. That is a significant cost. I just can't see myself spending that money for a 4 in 12 slope roof. If it was 3 in 12, I would probably go for it. That stuff is expensive. Grace must be making a killing on that stuff. Winterguard will run me $780. A double layer of 30# runs at $240. If I could get the price around $500 to $600, I would probably jump on it. Any other brands that I can check the prices on.
 
#28 ·
deck armour, ice and water, 30# felt

I am going to use two rows of IW from the eaves.. Then 3o# felt up to the peak where I will use IW again because I am going to put in ridge vents. Any particular brand of vent tickle your fancy?? I used the Cobra mesh once, it seems ok. Would like a plastic prouct for straight lines. But, the one used on my garage lets little tree particulates in.. No mesh screen, just some hoaky diverters.

What has been the report on the GAF Deck Armour breathable membrane?
 
#31 ·
I decided to run ice and water all along the eves as well. There is a lot of damage where the gutters were. I'm guessing the gutters got backed up and ruined some fascia and sheathing. I bought certainteed brand "sand." It is the granulated version. Is this the one you use? The instructions say to install it over the drip edge, so I don't know if it will do anything to protect against the gutters. What are your thoughts?
 
#32 ·
There instructions are wrong. you overhang the facia then apply a 3/4"x 3/4" red cedar ground as a termination. then apply the drip edge over that. This is a Ice dam leak prevention detail and protects the vunerable joint at the top of the facia and bottom of the roof sheathing. It is optional to also strip in the flange of the drip edge with a 6" strip of I&W but not essential. Certainteed still has the old generic ARMA spec detail that is out dated. Common sence and never underestimate the ingenuity of a rain drop.

RooferJim
www.jbennetteroofing.com
 
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