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I need to put a new roof on my log home in the North Cascades. Problem: two north-facing valleys. There is nothing I can do to eliminate these valleys. They are there and we just have to live with them. Huge glaciers form in these valleys and mangle and scour everything in their paths, just as in the surrounding mountains. The pitch is 8/12 and there are also three large skylights within about five feet of the valleys. Currently we have a 20+ yr old metal roof with overlap seams. We were thinking of installing standing seam metal, but no one can guarantee that the standing parts won’t end up lying down under these conditions. I don’t think snow stops are a good idea; I think they will just get torn off. The snow can be over five feet on the ground and sometimes can amount to over two feet overnight.
We have considered a smooth plastic membrane applied over plywood, but I just cannot stomach the aesthetic of that on my log house. I thought flat sheets of galvanized (sort of like huge shingles) screwed down and utilitarian-looking would look cool, but nobody has ever done it and I don’t know if it would work.
Fire rating has to be the highest, also. So, any experienced suggestions?
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I'm unclear what your current problem is. Is there something in particular that you don't want scoured from the roof? If it's the gutters, give up - you live in snow country - drip edges over the doorways is the most you should aim for.
3 feet of snow stays on my 12:12 roof all winter. It is roofed with architectural shingles (lots of texture) and we have colder (i.e. stronger) snow than you do. But if you want the snow to stay put, a non-metal roof would be the biggest help.
Do you have problems with the skylights? Repost here with more info. -David
*You can buy rolled flat metal that matches the color of any metal roofing, and quite wide (30" if I recall correctly). I've done this on two houses we've built in Sierra snow country and it seems to work, greasing the skids quite well. We used the usual color-matched washered fasteners, just shorter (1.5") and kept them as far out of the valley as practicable, relying on Bituthane strips to bond the flat metal to the valley metal after running Bituthane underneath everything.Good luck!Don
*Hi, Ann, just wondering if you are getting glaciers in the valleys due to inadequate insulation in the roof/ceiling? If so, perhaps when you reroof, you could add a layer of foam before your finished roof, whatever it is, to stop the ice forming. Check "nail base insulation" on the web or here for more info.
*David, What I don't want scoured from my roof is the roof itself. I do not have gutters. The metal that is there now just gets mangled. The ribs get flattened and ice goes under the seams and lifts and twists the metal so it not only looks awful after the winter, but mice, bees and other critters get in and make their homes there.I do not want snow to stay on the roof. It would be a disaster above the skylights with the loss of heat through them and resulting ice formation. Right now skylights are not really a problem.Do you have any north-facing valleys on your roof? If it weren't for those, I would be OK, too. Thanks for your reply, Ann
*Splintergroupie? Thanks for the reply. Yes, I know some of this glacier problem is due to inadequate insulation, most definitely. Over the years the leaking into the fiberglass bats has flattened them completely, I'm sure. We are planning to use spray-in foam on the new roof, R46 in the existing 2x10 grid probably, then plywood, then tarpaper, then metal. I'm just worried that glaciers will still form. Snow slides straight down and when two snowslides meet they compress into ice, just as in a cirque in the mountains.So, I guess what I am looking for is some kind of assurance that my standing seams-to-be are not going to end up flat. This is a $50,000 project! --Ann
*Ann: Sounds like a hot roof, doing the normal hot roof kinds of things. I do have a north-facing valley on my garage roof (10:12) with no problems but both house (12:12) and garage roofs are cold roofs.If you can live with your current insulation (i.e. utility bills are acceptable), you could run 2x4's flat on the existing roofing, over the rafters. Re-sheath and re-roof while maintaining a continuous air gap from soffit vents to ridge vent. Then you won't be melting snow at the roof surface until spring when temperatures are warm enough for the melt water to run all the way off the roof. I realize that the skylights would be difficult to deal with in raising the roof elevation. Skylights in snow country alway worry me. Maybe a few more halogens inside would be a good tradeoff for the energy-drain and source of concern that the skylights are. Just pull them out and insulate and roof the holes.If you proceed with the re-insulation project, consider going with a cold roof. Put baffles in before sprying the foam so that an air gap is maintained from top to bottom, along the bottom of the sheathing. Ice dams and moving glaciers of snow pack are not required in snow country, really. Good luck. -David
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I need to put a new roof on my log home in the North Cascades. Problem: two north-facing valleys. There is nothing I can do to eliminate these valleys. They are there and we just have to live with them. Huge glaciers form in these valleys and mangle and scour everything in their paths, just as in the surrounding mountains. The pitch is 8/12 and there are also three large skylights within about five feet of the valleys. Currently we have a 20+ yr old metal roof with overlap seams. We were thinking of installing standing seam metal, but no one can guarantee that the standing parts won't end up lying down under these conditions. I don't think snow stops are a good idea; I think they will just get torn off. The snow can be over five feet on the ground and sometimes can amount to over two feet overnight.
We have considered a smooth plastic membrane applied over plywood, but I just cannot stomach the aesthetic of that on my log house. I thought flat sheets of galvanized (sort of like huge shingles) screwed down and utilitarian-looking would look cool, but nobody has ever done it and I don't know if it would work.
Fire rating has to be the highest, also. So, any experienced suggestions?