50yr shinge and 30# felt


#1

hello I have gaf timberline ultra (which they call lifetime which I guess is comparable to 50yr), and 30# felt for underlayment. two roofers are considering the install. roofer #1 says bad idea to install 50yr over 30# felt. take it back and get 15#. says supplier should know better and just wanted to sell more rolls. something about proper breathing. this makes no sense to me. Roofer #2 does not have any objection to it. what do you think? thanks in advance.


#2

Well generally 30lb felt is used for things like tile, slate, etc. but with all the good synthetics there’s not much need for it anymore. I don’t see any reason for using it…or not on a 50 yr shingle. If you’re paying top dollar for a roof then sure, go with the heavier felt if you like. Never heard it makes the roof not breath before; although there may be some truth to that statement.


#3

Where is this project located?

Have you considered gaf deck armour, or perhaps a peel and stick underlayment?

What type of ridge vents are being used with the 50 yr shingle?

Gaf offers a warranty provided three gaf componets are used, I.E. 50 yr shingle, timbertex cap, and cobra ridge vent.

In my area #15 is used on low slope only, greater than 4:12 is required #30.

James


#4

I have heard of 30# felt creating a vapor barrier (never actually seen negative results…), we usually use High quality 15# on new builds (roofers select or shinglemate) but on tear offs I have been using 30#.
I have noticed that the premium fiberglass felt has small holes from the factory, which is the reason I use the 30#.
If your roof doesn’t breath well it would be a good idea to stick with 15#, otherwise I don’t think it makes a difference.
30# is twice as thick so naturally it costs more, usually the same as 15# per roll.
2 sq per roll for 30# and 4 sq per roll for 15#, hence twice as expensive.

The premium fiberglass felts are more expensive than standard 15# and slightly cheaper than 30# per sq.
Standard 15# felt can get saturated in moderate rains and leak, very badly…
Standard 15# felt absorbs more water than *most 30# felts, so it tends to bubble up a lot more.
Standard 15# felt tends to shrink a lot also which causes it to curl and rip away from its fasteners ( side benefit: it shrinks tight to the roof and flat if installed correctly).
Standard 15# felt has a low tear strength so it is a bigger danger to the roofers if it is not fastened correctly.
Some roofers think that felt is not needed, I am not one of them…

If you are putting a 50 yr roof on your house it should have good ventilation.
If it has good ventilation the weight of the felt shouldn’t be an issue.
I prefer 30# felt for tear off work because I feel it provides better protection for the house during the re-roofing process.
I my experience I have found that Roofer’s select lays flatter and straighter and holds fasteners very well, it also has a good surface for walking on.
Shinglemate is a good product also but it is a little slippery in some circumstances and doesn’t lay out as straight and flat.

Basically stay away from the standard 15# felts.


#5

“says supplier should know better and”

Don’t expect much tech support from your supplier anymore. I am aghast at some of the things they tell me anymore


#6

all a supplier is, is a guy reading things out of a book. 99% chance that they have never touched any of it. and…they will push what they sell!!


#7

i dont know what the hell any of you are talkin bout.
i have never torn a shingle roof off, and said
"yep this roof failed because they used this type of felt or that type felt".

never.

you guys kill me.

and dont pull the snow card on me.
i hate when you do that.

and 30 yr shingles out last the 50 yr
here in tampa bay.

ive torn off more fifty yr demensionals than
30 yr.

thicker isnt allways better.

gweedo


#8

[quote]i dont know what the hell any of you are talkin bout.
i have never torn a shingle roof off, and said
"yep this roof failed because they used this type of felt or that type felt".

never.

you guys kill me.

and dont pull the snow card on me.
i hate when you do that.

and 30 yr shingles out last the 50 yr
here in tampa bay.

ive torn off more fifty yr demensionals than
30 yr.

thicker isnt allways better.

gweedo[/quote]

God has spoken… :slight_smile:


#9

Shaking my head at 3am.


#10

30# is best for steep slope, won’t get torn from foot traffic. Roof needs to breath through ridge and soffit vents, not felt paper.


#11

gtp make gweedo laugh.

and who is this kellsdad.
someone refer to felt in a footing matter.
i like him allready.

ditto his post.

gweedo


#12

You Florida kids are also forgetting about 4:12 slopes or lower (when shingles are used vs. roll product).

Double lap, 30 # felt is code for Florida in this situation.

& Gweedo, I’d have to disagree with you 100% on the “no felt” thing. No, check that. I will disagree.

I have spoken.


#13

gaf.com/Content/Documents/21021.pdf

please review this web page. I believe this might work well for you.


#14

Well you about 2 months behind good work!


#15

having reread the thread i knowticed i kinda yelled at all you guys when only the poster was saying that felt mattered, under shingles.

sorry sometimes i type before fully comprehending
what im reading.

gweedo.