On Sep 8, 5:09*pm, dpb wrote:
RicodJour wrote:
On Sep 8, 7:23 am, Tegger wrote:
RicodJour wrote :

I looked up the Ontario code online, and maybe it was the format, but
I found it confusing and ambiguous. *It clearly calls for eave
protection underlayment, but the wording for the rest of the roof is
unclear. *Since both the Ontario and NY codes are based on the IRC,
they should have a lot of similarity. *Not sure why there's such an
omission for the underlayment.
All I know is what I see, and I see a LOT around here. Not once, ever, have
I seen a new-home roofed with /any/ sort of underlayment, not even at the
eaves.

No one is arguing your personal experience. *I'm just trying to figure
out how, out of every area that has adopted the IRC which requires
underlayment, Ontario is okay with omitting it and makes no reference
to the manufacturers' instructions requiring it. *It's odd, and from
the other responses you can see that I am not the only one that finds
it so.

It appears the Code references the Canadian version of the ASME
Standards for asphalt shingles based on a summary of the Code
requirements I found which on installation says--

"* Shingles shall be applied according to methods outlined by the
National Standards of Canada. Roof slopes 1:3 and steeper shall conform
to CAN3-A123-M85. Roof slopes 1:6 to less than 1:3 shall conform to
CAN3-A123.52-M85"

So, looking for the applicable Standards, best I came upon was the
following to catalog pages from the sales site--

CAN3 A123.51-M85 (R2006)
Asphalt Shingle Application on Roof Slopes 1:3 and Steeper
Canada National Standard/Canadian Standards / 01-Dec-1999 / 23 pages

1. Scope

1.1

This Standard describes the minimum application requirements for asphalt
strip shingles or low slope shingles on roofs with slopes from 1:3...

CAN3 A123.52-M85 (R2006)
Asphalt Shingle Application on Roof Slopes 1:6 to Less Than 1:3
Canada National Standard/Canadian Standards / 01-Dec-1999 / 24 pages

1. Scope

1.1

This Standard describes the minimum application requirements for asphalt
strip shingles or low slope shingles on roofs with slopes from 1:6 to
less than 1:3...

Unfortunately, they're published Standards and not generally available
online which is what makes finding the info so tough.

I'd be willing to bet both either include the requirement or rely on
following manufacturers' installation procedure for the particular
product. *Universally afaik, the manufacturers' recommend same.

I'm still betting Code says "do it" even if it is widely ignored and
(apparently) not enforced.

--

I followed the same route, and came to the same online dead end. But
good job showing your work.

R