Ice And Water Guard As An Underllayment....

gator

for the whole roof. Has anyone ever done that? Would you still lay felt on top of that. Or is this too riduclous?

doubleaction

not really a good idea unless its a low pitch, your sheeting and shingles wont be able to breath and shorten the life span.

Same Old

Do you have a source for that? That doesn't make much sense to me. I see complete roof decks covered in Grace I&W all the time. Usually on higher end homes .

Teetorbilt

I see it done all of the time here, primarily under metal roofing, it's great stuff!

I was FULLY convinced after watching a restaurant under construction go through Francis and Jeanne (we were center-punched by both) with nothing but Grace for protection.

I'm not a roofer and have no idea what problems water under shingles might cause. My personal experience is that shingles don't seal THAT tightly. This is based on the ones found in my yard after 3 hurricanes in 2 yrs. BTW, those plastic strips do not dissolve or complement adhesion, I'm STILL finding them in some trees and bushes.

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Ed the Roofer

Remember, more than 90 % of all roofing projects are not ventilated properly, which includes the calculated amount of balanced intake ventilation to correspond to the calculated amount of exhaust ventilation.

Thia is from the Grace site about FAQ's.



Are Grace underlayments vapor barriers?

Yes. Grace Ice & Water Shield, Grace Select and Grace Ultra are vapor barriers. In full coverage applications, proper ventilation is necessary. When used in conjunction with metals that are particularly susceptible to corrosion, such as zinc, care should be taken to allow a means of escape for water that becomes trapped between the membrane and the metal.

Ed

dennis

It is not necessary and is wasteful in most cases.

Just because it's being done does not make it right. Although it will make a lot of extra "paying" work for future roofers.

"In full coverage applications, proper ventilation is necessary. When used in conjunction with metals that are particularly susceptible to corrosion, such as zinc, care should be taken to allow a means of escape for water that becomes trapped between the membrane and the metal."
I think that goes for shingles too. If someone insisted on full coverage I would install at least 30# over the I&W.

JMO one size does not fit all

tnt specialty

100% coverage w/I&W is not a good idea, IMO, (23+ years experience).

We just experienced a textbook example as what happens with inadequate ventilation;

Repaced a standard application 25 year old shake roof with a comp shingle roof w/100% I&W underlayment.

The local bldg. inspector failed the final roof insprction due to a "brown-colored" icicle that had formed just behind a section of fascia board.

Upon investigation, in the attic, we found the entire underside of the roof sheathing to be soaken wet, with evidence of black mold that had formed in previous years. There was no attic ventilation provided in the upper area; Only eave vents.

The old shake roof with no I&W at all, had functioned fine for 25 yrs. It must have allowed some "breathing". The installation of the air-tight I&W was the "straw that broke the camels back", so-to-speak.

Even after showing the homeowner, (which is a general contractor himself), he still insists the water stain on his wall is due to the drip edge on top of the I&W, instead of under it.

This is a mountain resort area that we do alot of work in. The locals "I&W" everything. It's actually to mask inferior craftmanship. If one puts 100% I&W, well then...it realy doesn't matter what you do with the primary roofing, does it? It's going to bite them in the butt...here in a few years.

We looked at another condo project that called us to fix a "leak"; There were icicles hanging off of the underside of the sheathing. The original construction had diverted all the bath vents into the attic space! It was a 10-15 year old complex. It just took this particular season's weather pattern to intensify the problem to the point the ceilings became stained. Again, black mold throughout the attic. They didn't like what we told them. They got another roofer.

Same Old

But proper attic ventilation is required in any case, what difference does I&W make? Do you honestly think vapor transmission through osb is significant enough to make any difference at all?
It doesn't seem to be the cause of these moisture problems.
If you cover the entire deck, can't you just go over the entire deck with another layer when it is time to re-roof? Why remove one layer of I&W?

tnt specialty

In this case there must be signifigant moister transmission. And, yes, proper ventilation is vital in a 100% I&W application. But as those of us "in the know" realize, most GC's, as well as HVAC contractors, (where the ventilation responsibility should actually lie), are either naive or just don't care as to proper ventilation, as are most building officials. That's why it's becoming such an issue. Houses are being built much "tighter" these days.

Back to the subject; The fact of the matter, is that 100% I&W on these applications is a waste of money. It's a typical "monkey see - monkey do" scenerio.

Teetorbilt

I want to reiterate that I'm not a roofer. I do notice these trends here.

Shingles. Felt and done as quickly as possible.

Tile. Hot mopped and left for many weeks.

GIWS, metal/tile. Left for months.

From a strictly common sense perspective, I would think that the GIWS homes were allowing the deck to dry prior to the foam application for a 'green home'.

I drive into/out of these new developments often and keep a mental record for no particular reason other than my own interest.

__________________
You can't solve you're problems with the same level of thinking that created the problems.

Albert Einstein

Ed the Roofer

TNT,

I think along the same lines as you do regarding the I & W and ventilation concepts. Good to have you join us.

You should post an introduction for others to get to know something about you or your company too.

It astounds me, that with ventilation being theoretically such a key concept for shimgle longetivity, decreased humidity and mold concentratons in the attic environment, and a greater comfort factor for the interior living quarters, that this issue is done incorrectly over 90 % of the time per manufacturers own studies.

I bid the job with the properly calculated ventilation and if the home owner wants to elect to decrease it because"everyone else" says it doesn't need it, I get a waiver signed that it is not meeting the manufacturers requirements. I also am stymied as to how lackadaisical the building inspectors treat this funcion of the building envelope.

The I & W surely reduces the permeance of any decking or roofing product in place and therefor should be ventilated to more substantial performance criterias.

Ed

RooferJim

testing 123

RooferJim

Full I&W is done an a lot these days, I would think that increased ventilation is key to get the full life expectancey of the roof. In a coastal envirement it does make perfect sence though.

RooferJim

dougger222

From time to time I'll Wintergaurd a whole roof system but I make sure there is plenty of ventilation. Put it on my whole garage when I roofed it last Summer and plan to do the same on the house shortly. 6sq 8/12garage with 4 air vents and the house is only 12sq 5/12 with ridge vent. Going to Winterguard the whole roof cap off the ridge vent and add 10 air vents, and put down Landmark Georgetown Gray to match the garage. Overkill? Yes, but I doubt it will leak.

jmorgan

In the Western Mountains GIWS full coverage is common. This is fine if the deck is vented as per code (1:300). I see ice dams building up 30-40' up from the eaves, usually associated with glue-lams or bearing walls underneath.
The reasons that Grace recommends drip edge on top of the GIWS are: 1. We classify the drip edge are a part of the covering roof and
2. We have had snow/ice blown up between the drip edge and the wood deck, this thaws and freezes, eventually popping the facia boards off. When the drip edge is placed under the GIWS, the facia board cracks are not protected.

Grace's Alpine Design Letter asks for ice dam reducing building designs (like ventillation, cold roofs, etc) and full coverage GIWS with 2 plys at valleys and eaves.

imho
Jim

dougger222

Just finished my personal house and Winterguarded the whole thing including up onto the stone chimney 6in with new flashing and counter flashing. The previous roofer used thin aluminum for the chimney fashing and just put tar on the top. Covered up the gap on the peak and installed galvanized painted air vents and doubled the ridge on Georgetown Gray Landmarks.

AaronB.

Well, crap, I did my house ten years ago with plain old #15 an a 25 year Timberline. Never a problem, never a leak. We get heavy snow and subzero here...but I know how to roof without the magic roll of sticky chit. LOL

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roofwiz74

lol,that's funny.
I love it when a shingler calls himself a roofer.

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AaronB.

In my mind, if youre a roofer, you had better be able to successfully roof any building.

__________________
http://www.roseroofing.net/
Seamless Industrial and Commercial Roofing Systems, Residential Repair. For Those That Demand Quality!
Free roof inspections within 12 miles of our locale.

dougger222

I was just thinking about putting the shingles right over the decking but didn't want it to flunk inspection. With the 3ft overhangs and 17ft rake decided to just go the rest of the way up. What the heck why not? Always been a fan of overkill.

AB, how do those Timberlines look? Just got off a 65sq 12/12 I did new 6 years ago and noticed cracking and areas were the shingles were missing sections. The roof is good to go for hail, but these problems are not hail related, they are at least Timberline 30's but thinking they may have been the 40's, will find out before I send the estimate to the insurance company.

BTW, I'd never use that thin 15# felt on my roof, Winterguard only!!! J/K. Next house will probably be a lot bigger than this one and doubt I'll have enough spare rolls laying around to do it.

I'm a shingler, felter, salesman, etc. Got born into it. My personal goal between the other 7 roofers in the family is to be the best. Last two years on top financially with my little brother closer than ever! Don't look at being the best either by making the most money, I want happy customers that bring me other happy customers. Oddly enough my little brother is the best of the 7 roofers, go figure. He was trained in 7 years ago and has adjusted very well to roofing.

My little sister is going to help me out this Summer starting two weeks from now. May use her mostly for helping with bidding and such. She's 19, engaged and going to college, last thing I'd want is for her to fall of a stinking roof! Who knows she may like it, think it's in the blood or something. When she was 12 she bundled for me 23 sq's in 8 hours and I didn't touch one bundle! She's little too. My guys will for sure be distracted between her and the other blonde 20 yo but oh well should make for a fun summer.