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I have specified Aluminum Snap-On Panels for a new residence that should be Orange County’s first LEED for Homes Platinum candidate.
As you know, waterproofing and durability are an important part of building a LEED home. Manufacturer's online specifications and “typical” CAD details were of great help in preparing some detailed flashing drawings for this complex roof. However, it is where these “typical” details intersect (at transitions of dormers, sheds, etc.) that I am having trouble detailing. I am used to working with asphalt shingle roofing that has sheet metal flashing – and where these transitions occur, I usually design a custom welded metal saddle to handle the transition between the ‘typical’ rake, eave, ridge and pitched counter-flashings. With metal roofing, I need a little more help. Can you recommend a reference for me?
Thank you.
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David,
With your knowledge of the flashing for asphalt shingles you have a very good grasp of what you need. The metal flashings for the panel you are putting on needs to be aluminum. We always take measurements and drawings and have it welded from aluminum, stainless steel or whatever metal we need.
One thing that I see done over and over again and that is wrong is the intersection of a dormer valley with the main roof. Part of the panel will go under the facia on the dormer but the roofer runs one panel from the ridge to the eave. What they do with the valley flashing is cut the panel on the same angle as the valley but 2 or 3 inches from center. They then slide the valley flashing into this angled cut. You then have to absolutely trust that intersection to sealant and there can be a lot of water coming down a valley.
Now for a better way. Run a panel 12" or so above the valley, facia, main roof intersection. Cut the leg off up under the soffit and then the panel will slide under the valley and on up the main roof a few inches. Install your valley pan to where it needs to go and it will have to be cut up the clipped on leg of the installed panel. Measure for your next panel to come down to where you have marked your valley for the open part--2"or 3" what ever you use to the ridge. This panel will probably be straight across for a few inches and then start up the valley. You get all your angles and measurements, leaving the bottom of the sheet and the valley side one inch long. You then cut and fold the extra inch underneath and hem flat--remember no cut edges are exposed. There you have it. Most panels will take a little work where you have the clipped seam overstepping another seam. On some panels we take the bottom sheet and cut the lip that hooks on the clips and cut it off to where the other sheet will set. Then it will go together nicely.
You have an intersection now that does not need any sealant. You do have a splice--we call it a slip sheet (thanks to Greg Clark of Clark Louver in Fort Worth Texas. The best standing seam man I know) for teaching me this years ago.
Some homeowners and builders don't like to have a splice and I hate them too but when I explain to them why this is done and it is absolutely maintenance free forever--they're okay with it.
When we start a metal roof that has dormers, the first thing my crew does is take a sawzall and cut the valley wider from the facia up the valle a foot and a half. We do all of them because a panel is going to have to fit partly underneath the overhang.
[email protected]
Or copy this URL:
https://www.metalroofing.com/spirit/comment/11109/find/
David,
With your knowledge of the flashing for asphalt shingles you have a very good grasp of what you need. The metal flashings for the panel you are putting on needs to be aluminum. We always take measurements and drawings and have it welded from aluminum, stainless steel or whatever metal we need.
One thing that I see done over and over again and that is wrong is the intersection of a dormer valley with the main roof. Part of the panel will go under the facia on the dormer but the roofer runs one panel from the ridge to the eave. What they do with the valley flashing is cut the panel on the same angle as the valley but 2 or 3 inches from center. They then slide the valley flashing into this angled cut. You then have to absolutely trust that intersection to sealant and there can be a lot of water coming down a valley.
Now for a better way. Run a panel 12" or so above the valley, facia, main roof intersection. Cut the leg off up under the soffit and then the panel will slide under the valley and on up the main roof a few inches. Install your valley pan to where it needs to go and it will have to be cut up the clipped on leg of the installed panel. Measure for your next panel to come down to where you have marked your valley for the open part--2"or 3" what ever you use to the ridge. This panel will probably be straight across for a few inches and then start up the valley. You get all your angles and measurements, leaving the bottom of the sheet and the valley side one inch long. You then cut and fold the extra inch underneath and hem flat--remember no cut edges are exposed. There you have it. Most panels will take a little work where you have the clipped seam overstepping another seam. On some panels we take the bottom sheet and cut the lip that hooks on the clips and cut it off to where the other sheet will set. Then it will go together nicely.
You have an intersection now that does not need any sealant. You do have a splice--we call it a slip sheet (thanks to Greg Clark of Clark Louver in Fort Worth Texas. The best standing seam man I know) for teaching me this years ago.
Some homeowners and builders don't like to have a splice and I hate them too but when I explain to them why this is done and it is absolutely maintenance free forever--they're okay with it.
When we start a metal roof that has dormers, the first thing my crew does is take a sawzall and cut the valley wider from the facia up the valle a foot and a half. We do all of them because a panel is going to have to fit partly underneath the overhang.
[email protected]
3/12/2008
Or copy this URL: https://www.metalroofing.com/spirit/comment/11108/find/3/12/2008
Or copy this URL: https://www.metalroofing.com/spirit/comment/11109/find/3/12/2008
Or copy this URL: https://www.metalroofing.com/spirit/comment/11110/find/Isaiah Industries, Inc.
3/14/2008
Or copy this URL: https://www.metalroofing.com/spirit/comment/11111/find/3/20/2008
Or copy this URL: https://www.metalroofing.com/spirit/comment/11112/find/1/10/2009
Or copy this URL: https://www.metalroofing.com/spirit/comment/11113/find/Isaiah Industries, Inc.
1/14/2009
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