Structural Insulated roof panels and snow; metal roof

[jrhode]

Hello, everyone. I've been absorbing a lot of info from this board for the last few months as I have started my project. Now I've got a situation of my own... I'm building a timber frame house with SIPs as the roof and exterior walls. It's a basic rectangle - 38'x52, with 5 dormers, 2 on front, 3 on back. 9/12 pitch. Just after the panels were put on we were hit with a little freezing rain (~1/4") and then some snow. (~1") I had put down the ice/water shield on the eaves and in the valleys, and papered halfway up one side. Now it's got ice and snow on everything and it doesn't look like it will warm up enough to melt it any time soon. (I'm in MN)

I should clarify that the skins of the panels are made of Exterior 1 OSB.

Is there anything I can do to get rid of the ice and snow on the roof? Will the OSB be damaged if I don't? What are my options? What do the professionals do? It probably won't get above freezing for more than a day here and there until late Feb. I don't like leaving it but...

While I've got your attention...

We're planning on putting on a standing seam roof. The roof panels are rated at r-40. I can't seem to determine if I should put sleepers down first, for ventilation and to maintain a "cold" roof, or just go right on top of the sheathing. Some say the panels provide a cold roof, some say "warm." If I do put sleepers down, do they run horizontally, or vertically? I've only seen them run horizontally, but how does that provide venting from bottom to peak? Do you leave gaps between the horizontal sleepers? Some say to put holes through the panels at the eaves/soffits to help ventilation to the peak. Am I overthinking this? Maybe I don't need ventilation that way, just an airspace...

Sorry for the long winded post. And thanks for any info. This has been by far my greatest single source of homebuilding info.

Jon

[steeve]

i ve seen badly insulated roofs stay clean of snow all winter with nice big icecycles on the edges, so i would think if you just put some heat in your attic everything should just melt down....

[jrhode]

Thanks for the reply, but hopefully my brand new R-40 roof isn't "badly insulated..." Also, there's no attic. Just vaulted ceilings throughout. The outside of the panel is the roof, the inside is the ceiling.

I guess I must have stumped the experts.

Here's a few pics to show what I'm talking about.

[steeve]

already insulated,R-40... oh well, spring is on the way... :wink:

[Rich]

Too bad you didn't have tar paper down yet... oh well it happens.
http://www.vermonttimberworks.com/skin.html

Vented cold roof.

[jrhode]

Rich,

So it looks like I'll just have to wait til it melts off. Will the OSB survive that ok? I can't exactly take it off if it doesn't! :shock: Maybe apply a layer of ply over it? I know some here aren't too fond of OSB, but I've never seen any sips built with plywood.

Will I have to remove the paper that's on there now? I got all the ice & water sheild down, and paper up about halfway on one side.

Thanks for the info on the cold roof. I imagine the metal roof supplier would be a good source for sleeper spacing, etc.

[Vector]

I'd tarp it until spring, or a spell of warmer, dry weather.

If you do tarp it and the weather gets warmer, it'll melt under the tarp, which shouldn't be too bad, but then you can take the tarp off and get it dry (maybe, depending on how much snow we do or don't get this winter).

You don't want it exposed to a full winter's worth of snow melting off, and then spring rains, for sure.

[Rich]

Yep - what Vector said. When it does get to a point where it's pretty dry take up a couple layers of the tar paper to see if there is any damage underneath. You'll probably be able to trace the route the water took under the tar paper if there was water there at all. If it doesn't look good - as in warped, buckled etc, I would consider removing the OSB - otherwise it should be alright.

[jrhode]

Thanks for the tips, guys. I wasn't sure if tarping over the coating of ice/snow was a good idea, but I can see the logic of covering it up now. There's not a lot of snow there now, just too much to continue roofing. So I'll be getting a bunch of new tarps tomorrow!

As for the osb, I'm really hoping it'll be ok as it's bonded to the foam core of the panels and think it would basically be impossibe to remove without destroying the rest of the roof. javascript:emoticon(':cry:')

I definately think now I'll be putting sleepers down under the metal roof. Some people I know in the construction trade have told me it's not necessary/overkill, but after reading up on it more, I don't want to take any chances. I am I right in thinking that the sleepers would go directly on top of the bare osb, with another layer of decking on top of the sleepers, then paper on that, then the metal? Or could I put paper down, then the sleepers, then the metal? (Skipping the second layer of osb/ply) I know it wouldn't be good for walking on...javascript:emoticon(':?')

Thanks!