Ice and Water..Should I?

One contractor will cut to 18â€

The link worked just fine. No need to copy and paste.

Sales pamphlets from GAF show ice and water barrier on the rakes. I’ve never, ever seen it done that way in real life. Not by union companies, not by established non union companies, not by hacks. Nobody. I’ve also never seen a rake edge leak, I’m not saying it can’t happen though.

1.) Yes, your roof opens an interesting debate on where ice and water barrier should be placed. I’m still not comfortable answering this question from those pics. I’d need to actually go up on that roof and really think about it for a few minutes. Personally, the area over that garage I probably would not use shingles on, or alternatively, I might ice and water barrier that whole thing if I was to shingle it, and also use a 4" exposure rather than the traditional 5".

2.) Ice and water barrier should be installed at ALL flashing points, under the flashing.

3.) Vinyl siding might be covering a can of worms flashing wise. The flashing under there might be acceptable, might not be. Tough call. You’re going to have to trust your roofer on that

Hope that helps. Good Luck.

i have only seen ice & water barrier on the rake edge once. never seen it at the peaks or hips. def. under flashing (not over.) if you went over flashing then that would defeat the purpose of the flashing. code in NY state is 24" inside warm wall.


Where did you have ice dams? Front or back?

Stupid detail is stupid to you. Not stupid to everyone. This detail is a common design over patios.

Take it down if you do not like it.

Thankyou so much for all your help. S&G, your comment about i+w over entire gargage reminded me that a contractor in the fall said same thing (winter came and I had to delay project until now). Are you mentioning it because the pitch is really low? Can you help me understand why you think a 4" overhang there might be more appropriate than 5"?. The pitch on the top roof is also really low (4.5 from front to peak; something less at peak back to backyard. Think I better talk to contractor more.

The Ice Daming I’ve seen has all occurred in the front of the house. Top gutter came away from the fascia and I ripped it off in the fall. Damning had been seen there and along the garage and porch area. I’ve included new pictures in the link above.

P.S. Regarding flashing, contract will call for replacement of all of it.

Thanks everyone for your extremely helpful opinions.

if you have 4 inches of the shingle exposed to the weather as opposed to 5 inches, the overlap is bigger and moisture is less likely to get under the shingles. Yes, it is because of the really low pitch that I mentioned these things.

I would want to put rubber on that ideally, but some people think rubber is ugly.

How on earth did we keep roofs from leaking before Ice & Water leak products were created and sold on the market!

Yeah the GAF info showing Ice & Water all over the roof in pretty much a sales ploy. Clients ask me all the time about it, and that’s just what I tell them.

FACT: Roofs don’t need Ice & Water shield to keep from leaking. Don’t get me wrong its a nice product to use but it can be “OVER” used.

Suggestions for usage:
The chimney that is 6 inches or closer to a valley. The pvc pipe that is right next to an attic vent or chimeny, or again the valley.

Thank you. You guys always give me something to think about. Final quesion on this topic. I really like the Slateline and it has a 7.5 exposure. Would I mitigate any low slope issues by doing entire garage roof in W+I and forgoing it in all other areas (other than under new flashing on other areas of the roof)

You could effectively mitigate the low slope issue by installing the felt underlayment on an 18 inch lap instead of the normal way its installed. But looking at your pictures it doesn’t look below a 3/12 anyways.

Massachusetts code calls for a min. 24"of I&W past the interior warm wall line. so that means with an overhang the three foot pass would in most cases be against code, this is why we always specify a min of 6’ of I&W and 18" strip on rakes.


first a few comments -

ice shield on rakes is a marketing ploy as previously stated. I have never installed it in Michigan on rakes - GAF has to make more $$ and it is not required in our state. Overkill !!

The roof can be all shingled. Ice &* water shield is standard on our jobs 6 feet. No need to go with a smaller exposure if you are going to use a dimensional shingle. You could if you use a three tab but why put a three tab on when you can make it look nicer with a dimensional.

As for your pics. Here are a few things I see wrong.

Pic #4 - looks like bath or some type of exhaust vent is going into a can vent. That is a no no - install exhaust vents for each one separately. (if that is what they are)

Pic #5 - Can vents with a power vent. That is a no no. Never mix can vents with a power vent or any other type of vent system. System will short circuit itself and not function correctly. Suggestion - Remove the power vent.

Atticinsulation - looks like you need baffles installed in soffits to allow for air intake. Are there any soffits on this house ? If not - make sure to get some in there so that all the above ventilation items are going t5o wrk effectively.

Attic interior 1-1 - cover that gable vent - short circuiting the ventilation system.

Just some things that I see… Pics aren’t the greatest so I could be wrong about a few things but you can correct me accordingly.

Good luck !!

I’m so impressed and thankful to you gentlemen for responding to all my questions. I sincerely appreciate it and am jealous of the customer who gets you as their contractor!

Picture #4- I like your recommendation Timothy.

Picture #5- Uh, oh!..If you can’t use cans with a power vent and you can’t use ridge vent with a power vent, why do power vents even exist? what can the power vent be used with? …Just when I think I understand!

Baffles- yes, like the idea of going for 'em (and will get gables covered). These run only above the soffits? Is getting the facia and soffits wrapped any issue for baffles? (Wrapping as much as I can in order to avoid maintainence).

Attic is only 700 sq so will look to set up 336/2 nfa with 60% intake(202), 40% exhaust(134). Now I just have to pick material. Is it ok to exceed these numbers as long as the 60/40 ratio is maintained? I am considering continuous soffit that would give me 272 in-take (4 8ft pieces @ 68 nfa each) and 180 exhaust (3 cans @60 nfa each). Is that a bad idea since the intake considerably exceeds the 202 needed?

The old wives tale of dropping the shingle exposure from say 5to 4 or whatever is a bad idea and not recommended by shingle manufactures. The reason is when you lower the exposure you also lower the edge from the self seal strip and make it a lot more likley to blow off in high winds.


[quote=“nmchugh6”]I’m so impressed and thankful to you gentlemen for responding to all my questions. I sincerely appreciate it and am jealous of the customer who gets you as their contractor!

We all appreciate the compliments - we all strive to be the best we can be and glad to see you are taking advantage of it !!

Picture #4- I like your recommendation Timothy.

Picture #5- Uh, oh!..If you can’t use cans with a power vent and you can’t use ridge vent with a power vent, why do power vents even exist? what can the power vent be used with? …Just when I think I understand!

Check out this link. Just one of the ventialtion manufactures.


good luck whith your porject and feel free to ask any more questions.

its 3 things,proper attic insulation to keep the heat where it belongs,proper eave and ridge venting to dissipate any escaped or radiant heat(w/this its recommended to close off gable louvres,and eave flashing w/ice&water shield at least 2 ft.past the bearing walls,at wall junctures and skylights,it is recommende up the wall as a back-up to the flashing and to prevent entrance to wind driven rain/ice back-up

I understand all the ventilation aspects and can’t believe I am back to sq 1 regarding… tear-off! Contractor friend said I’m a fool to do a tear-off. He said the first layer will provide extra protection and that the only reason to tear-off is if I already have two layers (I have one) or if I have leaks. (I really don’t see anything inside except for one area above where two roofs meet; another area is a little more perplexing…I see odd marks (streaks) on the inside of an exterior wall. (The interior wall was painted in the last year…almost like greasy streaks…somewhat uniform…trying to explain that I don’t think they’re the product of a poor paint job)!

One final opinion on tear-off vs layover please

I’ve ran ice and water up rakes a few times but only with cedar soufit when it’s painted a color that no drip edge could match and when there are two cedar boards outside of the facia board past the decking. I cut it either in half or in three’s.

It’s overkill and I’ve only seen rot on the rakes at the eave rakes usully only a couple feet up the rake from the eave.

Another thing I do on all tin courses that I rarely see done is I like to cut the Winterguard in half and slip the factory cut edge up under the tins tight to the wall. Again, this could be overkill but never seen one leak this way.

It is noy necessary for I&W over an unheated garage,but it may be beneficial to have backflashing and 3ft I&W if your gutter water backs up there(even indiana-ive seen it)---look at your soffit at the fascia overhang-if the paint is peeling,nd you see the heads of nails holding the soffit board are rusted-then its a water backup problem and you should use it :wink: