Albert wrote:
I've recently discovered the benefits of sprayed in foam, just in time
(I hope) to use it when we finish renovations in our home in rural
Maine. I'm having trouble with the roofing issue however and local
roofers here don't know the answer as few of them do metal roofs at
all (standing seam) and even fewer have experience with sprayed in
foam.

We have a very mildly sloped roof, (mono sloped roof facing east). We
had a metal roof put on 4 years ago and are very happy with it, snow
slides off despite the fact that there is very little slope (less than
1 inch rise for every 1 foot).

We also have marginal roof rafter size, they are 6 inch dimensional
rafters. We have a single wall in the middle of the house with about
14 feet of span on each side of the center load bearing wall. With the
marginal roof rafter size, it is imperative that snow slide off the
roof, if it was allowed to sit there and accumulate, it would surely
cause the roof to collapse, especially when back to back blizzards
occurr).

When we do the renovations in the Spring, we hope to leave the 6 inch
roof rafters and spray in 4 inches of foam. This should drastically
improve the heat loss, but I'm concerned that the improved insulation
will cause the snow to build up and stay on the roof instead of
sliding off as it does at present.

I can't find anyone who knows about this and I need to know whether we
can salvage the existing roof rafters or whether we need to redo them
with 10 inch rafters. Obviously, replacing the rafters will be
horribly expensive compared to salvaging the existing rafters.

Do we need to dump the existing rafters and install a roof with a
steeper pitch or is there a way to reuse the rafters that we have?

Thanks,

Art in Maine

mail to ky1k aatt pivot ddoott net


I can't quite figure out what you are going to do, but it sounds like
you may be asking for trouble. Is there any kind of attic or area between
the living area and the roof deck? You really want that ventilated.

BTW snow that does not melt off the roof is good snow. It provides
additional insulation and it means there will not be Ice dams because the
snow is staying snow. The problems happen when the upper part of the roof
gets warm and the lower edge does not.

--
Joseph E. Meehan

26 + 6 = 1 It's Irish Math