The New Home for the Sheet Metal Industry Forums
SheetMetalTalk
 


Go Back   Sheetmetal Talk > Sheet Metal Forums > Metal Roofs

Metal Roofs
Discussion forum and information on Metal Roofs.


Share This Forum!  
 
 
     

 

Reply
 
Thread Tools Display Modes
  #1  
Old 08-20-2015, 09:37 PM
tinnerjohn tinnerjohn is offline
Member
 
Join Date: Nov 2004
Location: N.E. Ohio
Posts: 89
Thanks: 35
Thanked 20 Times in 15 Posts
Default Flat Seam Roof

I have a dormer on my house with about a 1 - 12 pitch that I need to re-roof. I've used roll roofing on it in the past, but the quality seems to have gone downhill since the first time 20 years ago. I'm thinking of using 28ga. galvanized 14 X 20 with 3/8 soldered seams, let it weather over the winter and paint it in the future. Now for my question: should I use felt or rosin paper over the plywood sheeting? Any comments, suggestions? I know rubber is probably what I should use, but I'm a tinner at heart! John
Reply With Quote
  #2  
Old 09-12-2015, 11:13 PM
b.c.tinbasher b.c.tinbasher is offline
Member
 
Join Date: Mar 2011
Location: Central British Columbia
Posts: 76
Thanks: 12
Thanked 9 Times in 6 Posts
Default

It's been a while since your post, did you go ahead and use the metal?
Reply With Quote
  #3  
Old 09-13-2015, 07:39 AM
tinnerjohn tinnerjohn is offline
Member
 
Join Date: Nov 2004
Location: N.E. Ohio
Posts: 89
Thanks: 35
Thanked 20 Times in 15 Posts
Default

Not yet. I was in a slow time but as soon as I started on my own projects, the phone started ringing! I am also thinking about using the rubber like ice dam. The existing roof should make it through the winter. Glue down rubber would be best probably, but like I said, I'm a tinner! John
Reply With Quote
  #4  
Old 09-17-2015, 02:13 AM
MattM MattM is offline
Professional Member
 
Join Date: Nov 2007
Location: Omaha, NE
Posts: 318
Thanks: 41
Thanked 38 Times in 29 Posts
Default

I wouldn't leave any galvanized exposed to direct rain and used as your roof material in any thickness less than 24 gauge. Think how insignificant the zinc coating is on 28 gauge. Fine for interior uses. Absolutely low quality in external applications.

If you want ridiculous thin material use aluminum. Whatever you use do not skimp on ice and water shield underneath.
Reply With Quote
  #5  
Old 11-20-2015, 02:45 PM
benjaminphanco benjaminphanco is offline
Junior Member
 
Join Date: Feb 2013
Posts: 18
Thanks: 3
Thanked 11 Times in 6 Posts
Default low slope metal roofing

a standing seam roof with seams that are 2" tall is acceptable down to 1/4 in 12 roof slope on panels less than 15 ft long in most materials. The problem is the perimeter capillary action. There are ways to stop this capillary action. Standing seam rake/gable, non-penetrated drip edge, and swabian eave detail.
https://www.youtube.com/watch?v=IoE0m0R-n0c

The standing seam rake stops water from rolling around the side and sucking under the panel.

the non-penetrated drip edge allows a continuous cleat point necessary for wind protection at low slopes and acts as a capillary shield with a water stop at the back. the backside water check also allows cleats to be placed to allow thermal motion of drip edge. When using this type of drip edge to stop capillary action it must be set in a lower plane than the rest of the roof deck.

the main benefit of the swabian eave is that it sheds more water off the roof than other seam end details. most of the water on a standing seam roof runs along side the seams. the swabian eave detail dumps the water off the panel beyond the drip edge.
Attached Images
File Type: jpg rake detail.jpg (29.9 KB, 22 views)
File Type: jpg non penetrated drip edge.jpg (62.5 KB, 22 views)

Last edited by benjaminphanco; 11-20-2015 at 03:00 PM. Reason: left a part out
Reply With Quote
The Following 2 Users Say Thank You to benjaminphanco For This Useful Post:
Bud (11-21-2015), Milo (11-24-2015)
  #6  
Old 11-20-2015, 03:03 PM
benjaminphanco benjaminphanco is offline
Junior Member
 
Join Date: Feb 2013
Posts: 18
Thanks: 3
Thanked 11 Times in 6 Posts
Default Sorry one doodle didn't come through properly.

Here it is.
Attached Images
File Type: jpg non penetrated drip edge.jpg (43.6 KB, 29 views)
Reply With Quote
The Following 3 Users Say Thank You to benjaminphanco For This Useful Post:
Bud (11-21-2015), Milo (11-24-2015), tinnerjohn (11-21-2015)
  #7  
Old 07-29-2017, 09:40 PM
artguymark60 artguymark60 is offline
Junior Member
 
Join Date: Apr 2016
Location: Marietta Ga
Posts: 9
Thanks: 1
Thanked 3 Times in 3 Posts
Default

Quote:
Originally Posted by tinnerjohn View Post
I have a dormer on my house with about a 1 - 12 pitch that I need to re-roof. I've used roll roofing on it in the past, but the quality seems to have gone downhill since the first time 20 years ago. I'm thinking of using 28ga. galvanized 14 X 20 with 3/8 soldered seams, let it weather over the winter and paint it in the future. Now for my question: should I use felt or rosin paper over the plywood sheeting? Any comments, suggestions? I know rubber is probably what I should use, but I'm a tinner at heart! John
Use both felt and rosin paper.
Reply With Quote
The Following User Says Thank You to artguymark60 For This Useful Post:
tinnerjohn (07-30-2017)
  #8  
Old 07-30-2017, 03:46 PM
tinnerjohn tinnerjohn is offline
Member
 
Join Date: Nov 2004
Location: N.E. Ohio
Posts: 89
Thanks: 35
Thanked 20 Times in 15 Posts
Default

This project is still on the backburner, I have the metal cut, just need to seam, paint the bottom side and install. I appreciate your suggestion, I'm guessing the 30 lb. felt, then the rosin paper? John
Reply With Quote
  #9  
Old 08-04-2017, 06:31 AM
MattM MattM is offline
Professional Member
 
Join Date: Nov 2007
Location: Omaha, NE
Posts: 318
Thanks: 41
Thanked 38 Times in 29 Posts
Default

I'm just curious, with 26 gauge so inexpensive, hardly different than 28, why go so thin? You can go aluminum if you're worried about weight. I would want 24 gauge minimum myself.

And letting it 'cure' in the weather will advance its failure considerably. May as well use primer or some other protectant ASAP the project is finished. Any non-protected exposure of galvanized drastically shortens its life. And it's even worse as air quality falls. Make your baby outlast you.
Reply With Quote
Reply

Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off


 

All times are GMT -6. The time now is 02:45 AM.


Powered by vBulletin®
Copyright ©2000 - 2018, Jelsoft Enterprises Ltd.