Metal Roof Waterproof Materials

[chencfp]

I would like to learn more about metal deck roof with waterproof material construction details. I am wondering if some one here can give me suggestions or references. Thanks.

 

[hokie66]

It would help to know where you are, as the materials and methods vary from country to country. It is easy to give you this information from Australia, because we use mostly metal roofing. In many countries, that is not the case.

 

[DonPhillips]

And depending on the size of the building, its construction type, occupancy, and location from the property line and/or other buildings, it will influence which roofing system is permitted. Not to mention the pitch of the roof.



Don Phillips

http://worthingtonengineering.com

 

[Ron]

chencfp...you mentioned metal roof deck with waterproofing materials. I would assume you are looking for information on structural metal decking with some type of roof membrane system on top. If that is the case, there are several texts and resources. The better of the textbook sort is "Manual of Low Slope Roof Systems" by Griffin and Fricklas. Further, you can consult the Roofing and Waterproofing Manual of the National Roofing Contractor's Association (a US trade organization headquarted in Chicago, Illinois). There are literally hundreds of proprietary details available, depending on the system you select. Don't forget to check the structural aspects of the deck system (diaphragm, attachment, uplift, venting,etc.)

If you are looking for information on metal roof panels that will serve as the waterproofing system for the building, you can consult many of the panel manufacturers (Fabral, Butler, others) as well as the National Association of Architectural Metal Manufacturers (for finishes) and the Metal Roofing Alliance (

http://www.metalroofing.com/)for

further information.

 

[chencfp]

Thank you all. The project is in NY. We use metal roof deck on WF beam (flat roof). I don't have any experience for details above metal deck. I saw some project around this area. They use insulation, rubber sheet, and apply some liquid (for waterproof?). But I don't known how those layers attaching to the roof. Ron provide a very good references (Thank again). I wondering if someone had a typical construction detail example for this type roof.

 

[Ron]

chencfp...it takes a lot more than a single detail to do this. You will have details for decking attachment, lapping, side lap fasteners, specifications for welding, specifications for welder qualifications (note that the welder must be qualified under the sheet metal code...not just the structural code). You then will have details for the roof membrane system, specifications for such, details for penetrations, perimeter flashings, etc.

It's reasonably involved.

 

[chencfp]

Ron, Thank you for your help. I am right now starting to read your provided references. One more question for you. I saw some projects in this area and typical roof span is around 5-ft. Is it adequate to have span at 9-ft (more than 3 spans)if we use thick metal deck (ie, 18 gage deck)?

Thank you again and Happy New Year.

 

[Ron]

I would not recommend such long spans. During roofing, deflections could be high and more opportunity to compromise weld fastening. Further, if you have a wind uplift condition, spreading the joist spacing will decrease the weld spacing such that you might not be able to get enough weld area to achieve uplift resistance.

Stick to around 5 feet for the spans.

 

[jike]

5 or 6 feet is typical for 1.5" metal deck. 8 to 10 feet for 3" metal deck. We only use 3" deck for joist spans over 100-120 feet or farther, although diaphragm capacities of 3" deck can sometimes be a problem.

 

[chencfp]

Ron, Jike, Thanks.

We will use 9' oc span (we use WF beam instead of barjoist), the clear span will be around 8'. Beside the welding (metal deck weld to WF) and metal deck deflection, what other problems I need to concern according to your experiences? Thank again.

 

[hokie66]

Using long spans, I hope you have taken Ron's and jike's advice to use 3" deck. You won't be able to walk on the 1.5" stuff, and your roof will leak.

 

[chencfp]

hokie66, Thanks. We will use 3" gage 18 deck.