I just finished sheathing the roof on a home that I am building for myself. It is a cape with a steep 14 pitch roof, on one side there is a shed dormer that is 7 3/4 pitch. There are exposed rafter tails and coravent between rafters as well as continuous ridge ventilitation. I am going to air-seal and insulate really well. Also there is about a 15″ overhang on the roof, which translates to nearly 2′ up the roof sheathing before it is over conditioned space. I live in the Hudson Valley of New York where we do have heavy snow and about 6,500 heating degree days. Also, I have already purchased a premium synthetic underlayment called titanium UDL. It is good in UV up to 6 months and has great traction and is somewhat self sealing around nails. I have 3 dog house dormers on one side and a shed dormer on the other.
Given all this info, do I need a layer of ice and water shield along my eves, and if so should I start it up higher since the first two feet will definately be cold? Should I use it in the valleys?
I will provide more information if needed. Thanks for any advice, I am a totally green roofer, but I’m looking forward to the challenge!
Replies
Yes use it all the way out to the eaves... and definitely in the valleys!! Why waste all that money on the other stuff just to save a couple of hundred bucks on bituthane??
Then do you think I should use 2 courses since a 3 foot strip may not go as high as potentially melting snow?
Use as many courses as necessary to take it from the edge of the eave to at least two feet inside the exterior wall.Rich BeckmanAnother day, another tool.
Also use it where the domer walls meet the roof. I would use Grace Ice and water, its more about $94 for a 2.25 sq roll (3'x75) than the granulated I & W but it is far better. It very sticky, so don't make a mistake putting it down. If it sticks to itself, you'll never get it unstuck. At the JLC show, Grace had a product called roof detail membrane or something to that effect that was about 18" that would be good for the domer wall to roof area, around skylights, etc.
When I do a lot of flashing work I sometimes cut a whole roll of Ice & Water Shield into the desired size with my sawzall.. this works best if the membrane is cold so it isn't so sticky (on the blade). I agree that Grace is still the best as far as protection over any of the other brands that I've seen or used... that granulated stuff is just junk in my opinion. Grace can be a real PITA to use but if you take your time and keep the roll out of sunlight whenever possible it helps (keep it cool). I also agree that you should run it beyond the wall at least two feet... I like to run it a little higher myself (usually about 3 feet) but I'm the one who gets dragged into court if they have ice or water damage.... just covering my butt!
typical is to run the I&W 3' back beyond the wall, so with a 2' overhang, you are going to run two strips, giving you four feet up onto the real roof.
Definitly use in valeys too
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That's the way I've always understood it too Piffin. 3' from the wall line, not the edge of the roof so 3' would be the minimum.View Image
NYS code says if the average temperature in January is less than twenty something degrees its required. I don't have the book in front of me, but in the Albany area its required.