6 ft ice& watershield

I install arh. Shingle on 12/12 pitch with 12 inch kick outs around. One cours ice&water shield & synthetic felt. Inspector require add one more cours. I just cant agree with that mentaly. For me always more imp. Proper ventilation, not extra feet ice&w with 12/12 pich roof. Is it so nesesary for high steep roof?

Code here states I+W must extend 2’ past interior wall line. With a 12/12, that could take 2 courses.

So. 5/12 roof with one course is enough and more waterproof like 12/12 roof with one course?

Depends on width of soffit. We have to install 2 courses on some houses. Codes vary.

Your opinion doesn’t matter; what the inspector wants, the inspector gets.

12" suffit, 12/12 pitch. Cant agree w 6 ft, only will create more heat and more ice in north side

We have to go 18" past outside/inside wall, regardless of what our opinion is.

Do it the way the inspector wants and when ice does back up the roof, then you can come back and repair it, for a fee of course.

You need more Ice and water shield as the pitch increases. The most likely area of heat loss is where the wall meets trusses because there is less room for insulation, more difficult to properly seal, etc etc.


The drawing on the left is 5/12, and on the right is 12/12. if you get heat loss 24" from the inside wall, there’s a lot more chance for leaks on the 12/12 than on the 5/12. Really there should be at least another half layer of I&W on the 5/12 as well.

Edit: this drawing is actually extremely generous in terms of space for insulation and ventilation. Unless its a raised heel truss you’ll be lucky if there is 4" of space between the top plate and the deck. Take away a couple inches for ventilation and that gives you all of 2" of insulation trying to stop heat from the inside. I agree ventilation is very important but the codes are there for a reason.