On Mon, 8 Nov 2004 12:44:53 -0600, (m Ransley)
wrote:

With a new metal roof you will be good for a long , long,time, So the
roof is actualy your ceiling height, a heated area. how it it finished
now, drywall? And why do you think it is under supported. Yes than
foam would be good but 5.5 " foam is R 30.25? @ R. 5.5 per inch. Well
under minimum code for my area which is zone 5. Maybe an Architect
should be consulted for roof strength. Beams could be staggered to every
other joist to give more depth and get more insulation, but I see roof
hight is a concern . Also the silverfaced foamboard is R 7.2 per inch .
5.5 inches of that will gain you an Extra 5.5 R bringing you to the
minimum codes for most Zone 5 areas. But I believe in alot more. So you
will remove the drywall or ceiling to insulate? The snow will probably
slide but call the roof manufacturer they will know best

I'm not too worried about the ultimate R value, especially since I'm
not using fiberglass insulation for the renovation.

Yes, the area under the roof is living space. It's a full floor where
we have all our bedrooms. There is no attic, crawl space and the
indoor ceiling height is 5 feet on the low end of the house and 7 feet
at the high end. The slope on the ceiling is also the slope of the
roof and there is nothing to ventillate.

If we can salvage the existing roof support structure, then we will
remove the drywall from the ceiling and spray from the inside and
install new drywall. If we have to do a whole new roof from scratch,
then we will probably install a trussed roof with new covering and
insulate it from the top side (before putting plywood down).

Ceiling height is an issue. But, the kids room are on the low ceiling
height room, so they can live with low ceiling heights for quite a few
more years.

If we have to tear everything out, we will redo it properly and
everyone will have 8 foot ceilings.

Since our single slope roof is nearly flat, I think the snow load
slides off because the existing fiberglass insulation is so poor and
heat from underneath melts some snow which allows the snow to slide
off.

All this goes away IF we reinsulate with foam, and the snow will tend
to sit there because the heat loss will be much less. If we get 2 or 3
blizzards back to back (which happens sometimes), we could end up with
more snow than the roof could handle since we have 6 inch rafters and
a 14 foot span between the outside wall and the center load bearing
wall.

My original question was regarding the snow slide on a metal roof with
super insulation. If the snow will just sit there with a modest pitch,
then we are headed for trouble. If the snow will slide off anyway,
then we can save a big pile of money by just salvaging the existing 6
inch roof structure.

All comments appreciated.

Art



PS:

Just notice I forgot to answer your questions...

I believe the present roof is under-supported because it is 14 feet
between the load bearing walls and the rafters are only 6 inch (1 5/8
by 5.5). Despite the very modest pitch, snow slides off the metal roof
quickly after a storm.

The downstairs is nearly all open, and there is only one solid
interior wall to transfer the weight of the center of the roof down to
the basement floor. The distance from the center load bearing wall to
the outside wall is 14 feet and the roof rafters are 2 by 6's.

I'm worried that the snow won't slide off so quickly if we super
insulate as planned and that the snow load might cause the roof to
collapse.

-----------------

Also, right now, the upstairs is dry walled (walls and ceilings) but
not highly finished or polished. There would be little lost if we had
to redo the entire interior up there as it was never properly finished
anyway.


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