sheet metal
Home | Library | Support | Forum Home Page


Go Back   The Sheet Metal Shop > 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, 08:37 PM
tinnerjohn tinnerjohn is offline
Member
 
Join Date: Nov 2004
Location: N.E. Ohio
Posts: 83
Thanks: 33
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, 10:13 PM
b.c.tinbasher b.c.tinbasher is offline
Member
 
Join Date: Mar 2011
Location: Central British Columbia
Posts: 78
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, 06:39 AM
tinnerjohn tinnerjohn is offline
Member
 
Join Date: Nov 2004
Location: N.E. Ohio
Posts: 83
Thanks: 33
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, 01:13 AM
MattM MattM is offline
Professional Member
 
Join Date: Nov 2007
Location: Omaha, NE
Posts: 315
Thanks: 37
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, 01:45 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 Thumbnails
rake detail.jpg   non penetrated drip edge.jpg  

Last edited by benjaminphanco; 11-20-2015 at 02:00 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, 02:03 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 Thumbnails
non penetrated drip edge.jpg  
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 11-21-2015, 05:10 PM
tinnerjohn tinnerjohn is offline
Member
 
Join Date: Nov 2004
Location: N.E. Ohio
Posts: 83
Thanks: 33
Thanked 20 Times in 15 Posts
Default

Thanks Benjamin. I had not thought of the capillary action at the eave. The roll roofing is still on there, but next year I will definitely have to replace it. You've given me food for thought! John
Reply With Quote
  #8  
Old 11-24-2015, 07:57 PM
Milo Milo is offline
Member
 
Join Date: Jun 2009
Location: NW PA
Posts: 58
Thanks: 8
Thanked 20 Times in 13 Posts
Default

Here is another similar detail of the non penetrated drip edge found in the UK copper roofing manual.
actual detail SEE fig 26a on PAGE 73 it describes both low AND higher pitch (>20 deg) roofs: http://admin.copperalliance.eu/docs/...rsn=2&sfvrsn=2

from publication on this page:http://copperalliance.org.uk/resourc...fing-in-detail

The book itself has alot more info but many details are found on the website.

Benjamin,
do you have any photos of the standing seam rake/gable?

MILO

Last edited by Milo; 11-24-2015 at 08:28 PM. Reason: Added question
Reply With Quote
The Following 2 Users Say Thank You to Milo For This Useful Post:
Bud (11-24-2015), tinnerjohn (11-25-2015)
  #9  
Old 10-19-2016, 05:24 PM
MattM MattM is offline
Professional Member
 
Join Date: Nov 2007
Location: Omaha, NE
Posts: 315
Thanks: 37
Thanked 38 Times in 29 Posts
Default

I'm not sure if you might be aware on Ben's detail that the first clip requires painted side down if you choose colored metal. You use this detail to create a clean appearance with the fasteners hidden. You will get moisture under your panels so your best underlayment choice should adhere to the first clip and preferably over your fasteners (flathead screws, ring shank nail, etc.) to keep your decking water tight. Over your clip is what we refer to as the "starter"; some refer to it as the cleat or other various names. If you have a fascia or paneling below the roof edge, starter makes a good clean finish.

Be also aware that no matter how much water tight you think the flat seam panels are, your air will deposit moisture underneath in the form of condensation from water vapors. You want that water to flow over protective underlayment and down the first clip. You will see minor drips from each lap joint between starter pieces. If you have drips you don't want them coming down the face of fascia or wall panels. Put a kink out at the bottom of both the clip and starter pieces. Your drips will then at least have a fighting chance to stay off your fascia or wall panels.
Reply With Quote
  #10  
Old 10-19-2016, 05:52 PM
MattM MattM is offline
Professional Member
 
Join Date: Nov 2007
Location: Omaha, NE
Posts: 315
Thanks: 37
Thanked 38 Times in 29 Posts
Default

tinnerjohn-

When you were talking about 14 X 20 did you mean that in inches and as interlocking rectangle panels? If that is the case you need something under your joints so you can solder.
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 12:12 AM.


Powered by vBulletin®
Copyright ©2000 - 2017, Jelsoft Enterprises Ltd.