Will properly applied underlayment keep a roof watertight?

vtroofing

Deck Armor. Leave it many nights in a row in rain no issues. Ranches and walk-ables may be the exception to the rule, but if its a ranch its easily done in a day. The bigger, even cut up steep ones no issues. Did a 100 square tear off, Deck Armored no weaving of underlayment on valleys, open with Weather Watch and no leaks. That was June of this year, rained mostly everyday not one leak. Felt, probably would have dried, shrunk and blown off.

FriscoBlue

Again I disagree,

Upon completing a slate roof it has potentially thousands of nails through the felt.

I believe my Slate roof is watertight, underlayment or not!!

That is the way I was taught in Europe on site and at trade college.
There are Slate roofs on some structures hundreds of years old, Historic buildings. There is no rot on these structures, until I see it I will not believe Slate roofs leak and depend on Underlayment!!

Out here in California a lot of the Roofing companies install a full layer of Ice and water on Plywood.

Now that will be a huge problem in a few years time!!!

I have been roofing 31 years, Love the Forum, I have learning every time I log on!!

Merry Christmas Guys,

FriscoBlue

RooferJim

Slate Roofs in the Boston area , even the ones that are one hundred years old almost always have a heavy felt underlayment. Tile roofing is even more important to have a good underlayment since it has no real headlap. shingle roofs are water sheding systems and are suseptable to wind driven rain. underlayment is an important part of the system as is good flashing and proper fastening. Nails through you felt has no bearing on it unless they rip the felt. How do you apply your felt ? nails right ? don't believe everything you read from Jenkins many real slaters find a lot of flaws with his methods. common sence is not always common.
RooferJim
www.jbennetteroofing.com

FriscoBlue

Hi Roofer Jim,

Agreed on the nails through the felt, however a plastic cap nail is driven home.

The heavy felt in the Boston area how long will it last? Will the Slate roof need to be replaced after the heavy felt is gone.

NO, the Slate roof will continue to last for many years after the felt has deterioted.

Guys, I am not against a good paper job, we leave nrew construction jobs felted in the winter without any leaks.

I would never rely on it as I know when it has reached the end of its life, the Slate will continue to be a waterproof roof.

Happy Holidays guys

English Roofer

Here in the U.K we use Tyvec breathable under felt to first make the roof water tight,it comes in a 1 meter(37") wide roll and is tacked or nailed on it is laid with a 6" head lap, the battens (2" x 1 ")are nailed in to the rafters and then the slates are nailed to the battens,the slate nails do not penetrate the felt, the slates don't sweat because of the breathable felt.
I use the felt to water tight the roof first,if i see any holes or rips then i repair these with mastic which will keep the roof dry till the roof is slated in, the felt in my opinion is just a secondry guard to the roof being water tight, the slates are the first.
I too have seen old slate roofs that don't sweat or leak, under layment was only used in this country from the late 50;s onwards, in fact my own roof has no under layment on it and doesn't leak, its the original roof from the 30's
Cheers
Dave

__________________
'I can resist anything but temptation'- Oscar Wilde
www.drroofing.co.uk

yanceyman1

First let me say that when this book was FIRST published, concrete tile was being hung on SKIP sheething. Of course, we all know how that one worked out! My point is this is 2011. Times have changed. The new underlayments don't, ( ”dry up and blow away”). These are from the Plastic family, not ragfelt. And we all know how long plastics have survived in landfills. Not that they will outlast slate, but they nolonger have the 25 yr. life they used to.
But wait, I must tell all of the slate and other journeymen roofers who have responded, THANK YOU. You are the kind of guys I would like to roof with. Take pride in your work and teach those ethics to the younger generation coming up behind you. Roofing my not be the nobleist of tne trades, but when we show up during a bad storm and water is leaking in everywhere....the lowly roofer becomes KING.!! So keep it up and thanks.
Now on to my real subject. When i started this thread, it was in reference to an 80 sq. CONCRETE tile job. So i don't want to drift to far from that subject. If you could, or rather, if you have the time, FriscoBlue and Waverunner, please read my thread on the newer Sharkskin undelayment. I would be very interested in your veiws.
Once again, Thanks to all & to all a Merry Xmas

__________________
"The Best Way To Appreciate Your Job Is To Imagine Yourself Without One". OSCAR WILDE

FriscoBlue

Hi Yanceyman1,

Sorry, I was the one who made the post drift off topic.

I have not laid a Concrete tile in 25 years, back when I did it was Marley major and Redland Stonewald, I think that is what they called them in Europe?

We used a heavy felt underneath and two layers of torch on in the valleys, low budget type of homes. We also used to nail a vertical batten in the rafter and then attach the Horozontal battens, this helped the water drain, opposed to what I have saw here nail the horozontol battens to the felt.

I have installed quite a few clay tile projects here in the USA, minimum underlayment has been two layers of 30LB felt, I have also used GAF Underoof 2 peel and stick, Grace and Ice water shield and Storm guard

I have not used Sharkskin nor will I after reading your post, thank you for the education on that.

I am a traditional guy and it takes a lot to switch me from the 30LB felt, I install two layers on every Slate and Tile job job.

I will keep reading the forum to find out how those synthetics are holding up. LOL

I do have a computer and not a typewriter so I can have a change of heart!! LOL LOL

To all you fine roofers on the Forum, thank you for the education, we can all help each othe to be better Roofing Contractors!!

Cheers for now.

English Roofer

I have not laid a Concrete tile in 25 years, back when I did it was Marley major and Redland Stonewald, I think that is what they called them in Europe?

We still use those tiles today, especially the Marley Modern tile, this is basically a concrete slate.
Cheers
Dave

__________________
'I can resist anything but temptation'- Oscar Wilde
www.drroofing.co.uk

vtroofing

Nobody commented on the Deck Armor, hmmm.

English- I just saw for the first time Tyvex for the roof in a local lumberyard.
Seemed like it might be slippery? Deck armor seems less than slippery, quite a bit thicker without being slippery-

I get tried and true felt paper- but up here felt is rare these days. Cost for 30# felt is about $20 a roll / 5 rolls ($100) to get to a full roll Deck Armor at $160 a 10 SQ. roll and the wind and the sun compared to the speed of installation explains the change.

Just my opinion, but curious to see others taking the same steps.