Need some advice


#1

I was wondering for some opinions here. I posted a question about using triply as an underlayment. I finally got a reply from Gaf saying it is not suitable but they won’t say why.

Here is my question what is the best replacement. I am going to shingle our cottage (thumb of Michigan)5:12 pitch 30yr Elk HD Wip ice and rain Shinglevent II ridge vent but now I am looking for underlayment.

Is titanium worth $160 a roll (ABC supply) what are my other options I don’t care for #15 #30 felt.Is titanium BETTER than other products?

The house has a mold problem in the attic but it only has can vents and no soffit vents I am adding shinglevent II and soffit vents every 3rd bay and plastic chutes. I am going to replace the top to rows of sheathing with new 1/2 osb not get rid of mold.


#2

There is nothing wrong with using either 15# or better yet, 30# felt.

It sounds as if you need to make sure you add even more intake ventilation into the attic system.

Try the Smart Vent from DCI Products. It is a continuous shingle over style Fresh Air Intake Vent that gets installed along the bottom eave edge on top of the decking.

Ed


#3

The problem with venting is there is no intake venting right now. It has 3 can vents and that is it. It is kind of weird it took 30 yrs to get mold??

I was just wondering if any of the synthetic felts are worth the price they cost. It almost sounds as if they are only for factory built homes and big jobs that need to be water tight fast.


#4

Joe ,I use shingle mate felt by Gaf. It lays very flat and is secure to walk on with just staples. It is fike a fiberglass weaved paper that goes with the Gaf/Elk.


#5

i have always used 15 lp felt


#6

Do you mean you were considering using #75 base sheet for a shingle underlayment?

It would help to know why you don’t care for #15 and #30. Is it connected to your concerns about mold?


#7

i beleive the titanium is a 10 sq rll.
yes its worth it.

gweedo.


#8

[quote=“gweedo”]i beleive the titanium is a 10 sq rll.
yes its worth it.

gweedo.[/quote]

Yes the titanium is good stuff.
It won’t let you down.

The base sheets that I use for torchdown are not suitable for shingle underlayment, they do not keep out water.
They are meant for torch applied modified, a surface to torch to…
I normally use GafGlas 75#, it has a sandy surface that will be very slippery on a sloped roof, and it does not keep out water…
It is not meant to.

If you want a good underlayment for shingles use a 30# felt or roofer select, or shinglemate, or a synthetic product like titanium UDL.
If you want to overkill your roof use Ice & water shield on the whole thing, if you have good ventilation…

If you insist on a heavy base sheet use a 43# asphalt saturated base sheet, this one will keep water out.
But your shingles will stick to it and the next roofer is gonna hate you for it…


#9

The reason I don’t like felt is for 10 bucks a roll more you get #75 base sheet which lays perfectly flat no wrinkles.

After talking to Gaf it is not suitable as underlayment because it is not class A fire rated or UL listed and can affect the fire rating of the shingle however it will not affect the shingle warranty.

I was really wondering if titanium was worth $160 a roll for a roof that will be cover quickly.It almost seams to only help people who will leave the roof unshingled for extended periods.


#10

Roofers select lays very flat, try it and you will like it.

It is not about the money it is about the best material for the intended purpose.
If you feel better by using a more expensive product use the Titanium UDL, it is very good stuff and as far as underlayments go it is very expensive.


#11

[quote=“Joe”]The reason I don’t like felt is for 10 bucks a roll more you get #75 base sheet which lays perfectly flat no wrinkles.

After talking to Gaf it is not suitable as underlayment because it is not class A fire rated or UL listed and can affect the fire rating of the shingle however it will not affect the shingle warranty.

I was really wondering if titanium was worth $160 a roll for a roof that will be cover quickly.It almost seams to only help people who will leave the roof unshingled for extended periods.[/quote]

Hi Joe,

Have you ever heard of Conbase MB40 SBS Fiberglas underlayment for use under tile, shingles, metal. Made by Conglas. This product passes a 6 hour shower test which means that if the water comes thru the MB40 in less than 6 hours, the product fails and because it is SBS rubber asphalt coated and fiberglas it has excellant sealing of fastener properties and lays flat without any wrinkles or buckles. I understand it is only available in Calif, AZ, Las Vag. Runs about $22.00 per 2sq. roll. Maybe you can find something similar in your neck of the woods. Good Luck

Casperboy