Here's a shot of an outside corner of the house wall where you can see what the walls are made of; solid 4x8 T&G cedar beams, even most of the interior partition walls, with the exception of a few plumbing walls. It creaks once and awhile as the wood expands and contracts, but it is VERY solid in high winds, and quiet inside. /forums/images/graemlins/smirk.gif
New roof on a cedar home... Some questions?
- Thread starter tomrscott
- Start date
- Views: 7566
Eddie,
I'm glad we cleared that up.
So I guess the only place we part company is that I still have trouble believing that a sheet metal roofing material can be stiff enough that I want to walk on it when it is only supported with perlins every 48" OC. I have a workshop roofed that way, and a barn roofed with plywood sheathing underneath, and there is no question the latter is stiffer and has held up better over the years. I just can't imagine any sheet metal roofing being heavy enough gauge that it wouldn't benefit from the full support.
On the other hand, Jinman's installation right over the top of the foam insulation blocks with no perlins, saves the sheathing costs and gives the same full support to the sheet metal.
I've got to go look at materials, shop costs, and look at the budget. Ideally, I'd like to do both the house and workshop at the same time, maybe with some similar materials.
As for timing, I am anticipating usable weather by June or July.
I'm glad we cleared that up.
So I guess the only place we part company is that I still have trouble believing that a sheet metal roofing material can be stiff enough that I want to walk on it when it is only supported with perlins every 48" OC. I have a workshop roofed that way, and a barn roofed with plywood sheathing underneath, and there is no question the latter is stiffer and has held up better over the years. I just can't imagine any sheet metal roofing being heavy enough gauge that it wouldn't benefit from the full support.
On the other hand, Jinman's installation right over the top of the foam insulation blocks with no perlins, saves the sheathing costs and gives the same full support to the sheet metal.
I've got to go look at materials, shop costs, and look at the budget. Ideally, I'd like to do both the house and workshop at the same time, maybe with some similar materials.
As for timing, I am anticipating usable weather by June or July.
jinman
Rest in Peace
- Joined
- Feb 23, 2001
- Messages
- 20,387
- Location
- Texas - Wise County - Sunset
- Tractor
- NHTC45D, NH LB75B, Ford Jubilee
</font><font color="blue" class="small">( On the other hand, Jinman's installation right over the top of the foam insulation blocks with no perlins, saves the sheathing costs and gives the same full support to the sheet metal.
)</font>
Tom, the metal is not applied directly over the top of the foam insulation. There is a layer of OSB sheathing on top of the foam and that is what is screwed down with the 5" deck screws. The metal is screwed down to the OSB by using normal self-sealing hex-head screws which match the color of the green roofing.
One other thing, I ran electrical wires on top of my 2x6 tongue and groove so I could have ceiling fans and lights hanging inside instead of all the lighting being on the walls. After the wire was installed, I covered it with 1" angle-iron for protection against screw/nail penetration. I didn't want to take a chance that one of those 5" screws would penetrate one of my wires and then possibly make my whole metal roof "live." /forums/images/graemlins/shocked.gif
)</font>
Tom, the metal is not applied directly over the top of the foam insulation. There is a layer of OSB sheathing on top of the foam and that is what is screwed down with the 5" deck screws. The metal is screwed down to the OSB by using normal self-sealing hex-head screws which match the color of the green roofing.
One other thing, I ran electrical wires on top of my 2x6 tongue and groove so I could have ceiling fans and lights hanging inside instead of all the lighting being on the walls. After the wire was installed, I covered it with 1" angle-iron for protection against screw/nail penetration. I didn't want to take a chance that one of those 5" screws would penetrate one of my wires and then possibly make my whole metal roof "live." /forums/images/graemlins/shocked.gif
Darren
Veteran Member
- Joined
- Feb 16, 2002
- Messages
- 1,038
- Location
- WVa
- Tractor
- Kubota L3710, Ford 5600, Case MB4/94, Kubota B6200
Thanks to Jinman, it looks like you can use the same system and save some weight. The rafters that only extend over the eaves support the framing that "packages" the foam. You don't need rafters that run clear to the peak.
As long as you don't put a concentrated load on the foam, it won't be damaged as you apply the decking to serve as a base to fasten the metal.
As long as you don't put a concentrated load on the foam, it won't be damaged as you apply the decking to serve as a base to fasten the metal.
Yeah I agree Darren.
This seems like a real good approach. I feel better understanding that he's got some sheathing over the foam to protect it -- as you say -- from concentrated loads. I'm sure 1/2" ply (or osb) would spread out any loading enough that it would be plenty solid. I am confident that sheet metal with solid backing is going to get less "buffetting" vibration that tends to tear the fasteners loose.
I think it must be hard for some people to visualize, but if the material can deflect inward under wind gusts, it will store tension that will deflect it back outward. The result will be an oscillating vibration that tears things apart slowly. You can prevent oscillations by dampening either half cycle of the vibration. With solid backing behind the metal, it will just lie there a lot more quietly and the fasteners will receive a lot less stress.
Yes you can do without the backing, and it's not the first-order concern, but I think it can make a difference over the long span of what should be a long term roof when you have the kind of wind conditions we have on top of a mountain.
Cheers all! /forums/images/graemlins/smirk.gif
This seems like a real good approach. I feel better understanding that he's got some sheathing over the foam to protect it -- as you say -- from concentrated loads. I'm sure 1/2" ply (or osb) would spread out any loading enough that it would be plenty solid. I am confident that sheet metal with solid backing is going to get less "buffetting" vibration that tends to tear the fasteners loose.
I think it must be hard for some people to visualize, but if the material can deflect inward under wind gusts, it will store tension that will deflect it back outward. The result will be an oscillating vibration that tears things apart slowly. You can prevent oscillations by dampening either half cycle of the vibration. With solid backing behind the metal, it will just lie there a lot more quietly and the fasteners will receive a lot less stress.
Yes you can do without the backing, and it's not the first-order concern, but I think it can make a difference over the long span of what should be a long term roof when you have the kind of wind conditions we have on top of a mountain.
Cheers all! /forums/images/graemlins/smirk.gif
bugstruck
Platinum Member
Eddie, Roger all your comments. Especially, the getting it lined up. Wasn't for that I'd be worthless I suppose. The OSB is nearly all you see on tract housing here for probably 10 years too. I just point these things out so others know what they are actually dealing with. People get so use to seeing these new products they may think they are as good or better than the old products. Many are, some aren't.
I'm strutin somewhat a-thread, so I'll chime out till something on-subject strikes.
Regards,
I'm strutin somewhat a-thread, so I'll chime out till something on-subject strikes.
Regards,
Darren
Veteran Member
- Joined
- Feb 16, 2002
- Messages
- 1,038
- Location
- WVa
- Tractor
- Kubota L3710, Ford 5600, Case MB4/94, Kubota B6200
I'd still check with a roofer that does standing seam roofs. I've seen those applied directly over metal trusses in commercial buildings without insulstion. Given the height of the seam, I don't think you're going to get any vibration. You may find that you can forget about using decking over the foam and apply the roofing directly on top. The money you save by eliminating the CDX or OSB might make the standing seam roof fit your budget. If so you'll have a roof that will probably outlast you and your kids.
bugstruck
Platinum Member
I like Jinman's solution. /forums/images/graemlins/smile.gif A lot. Very smart. That's how I'd go. SIPS is another one I'd consider. I just prefer Jinman's.
As we used to say in the 70's. It Rocks!
10-4 on the oscillations. That and thermal are the primary contributors to what backs the fastners out.
Should be a great job! /forums/images/graemlins/grin.gif
As we used to say in the 70's. It Rocks!
10-4 on the oscillations. That and thermal are the primary contributors to what backs the fastners out.
Should be a great job! /forums/images/graemlins/grin.gif
With regard to whether or not to use solid sheathing. Here is a clip from the Mueller web site on their standing seam product:
"Our Concealed Fastener (CF) Panel conceals the fasteners with our unique lock-joing system, with a minimum of penetrations in the exposed panel. This panel is for residential or commercial applications and should be installed over a solid substrate. It gives a smooth, clean look to any home or business. "
http://www.muellerinc.com/panels/cfpanel.php
Sounds like they prefer sheathing... /forums/images/graemlins/smirk.gif
"Our Concealed Fastener (CF) Panel conceals the fasteners with our unique lock-joing system, with a minimum of penetrations in the exposed panel. This panel is for residential or commercial applications and should be installed over a solid substrate. It gives a smooth, clean look to any home or business. "
http://www.muellerinc.com/panels/cfpanel.php
Sounds like they prefer sheathing... /forums/images/graemlins/smirk.gif
Darren
Veteran Member
- Joined
- Feb 16, 2002
- Messages
- 1,038
- Location
- WVa
- Tractor
- Kubota L3710, Ford 5600, Case MB4/94, Kubota B6200
Legalities are always interesting. Should has a different meaning than must. Should begs the question. When may you not apply it over a solid substrate? I suspect the gauge of the metal may play a part. I won't stand on the light gauge panels that are used on some pole barn roofs without placing a a 2x6 or 2x8 plank on the flats (not across the ridges) to avoid bending the panels.
With a heavier gauge metal panel on purlins instead of a solid substrate, it still won't dimple when you stand on it. Obviously the heavier the gauge the less panning you'd get in high winds and the more resistance to damage from hail or pressure from foot traffic.
If you had 1/4" plate on your roof, hail wouldn't dent it. The question is how heavy a gauge do you need. If you're going light, use a substrate. If you're buying a heavier gauge, you may not need the added strength of a substrate so you eliminate the decking and save money.
You need to figure the costs with each option and take into account the life you want out of the roof.
http://www.toolbase.org/tertiaryT.asp?DocumentID=2147&CategoryID=1402
With a heavier gauge metal panel on purlins instead of a solid substrate, it still won't dimple when you stand on it. Obviously the heavier the gauge the less panning you'd get in high winds and the more resistance to damage from hail or pressure from foot traffic.
If you had 1/4" plate on your roof, hail wouldn't dent it. The question is how heavy a gauge do you need. If you're going light, use a substrate. If you're buying a heavier gauge, you may not need the added strength of a substrate so you eliminate the decking and save money.
You need to figure the costs with each option and take into account the life you want out of the roof.
http://www.toolbase.org/tertiaryT.asp?DocumentID=2147&CategoryID=1402