Purlins/battens or not?

Guest User
3/31/2017
Hi, I am partway through a new build, and am getting conflicting advice from various people, so am hoping for the best-practice answer from you all. My roof is a simple one, no hips, no valleys, gable ends. The North facing side is 12 in 12 slope, south facing is 5 in 12, with extended overhang (passive solar design). Attic space will be well ventilated with continuous soffit and ridge venting. So far, I have trusses at 2 ft spacing, with 5/8in plywood over top. All horizontal ply joints are backed with 2x4 ladders between the trusses. Next step is Grace Select Ice+Water shield, Rhino roofing membrane. I am planning on having vertical seamed steel installed, screwed down. Also planning on eventually having roof mounted solar water heating and PV panels on the 5 in 12 slope. Questions that I have are; 1. Do I need to put down horizontal 1x4 timbers (purlins/battens) before installing the steel? If so, what spacing? 2. Screws in the valleys, or on the ridges of the steel? I live in Ontario, so lots of snow, not too much wind. Thanks in advance.
Todd Miller
Isaiah Industries, Inc.
4/1/2017
Thanks for your question. Based upon what you have described, I do not see any benefit to battens. If you told me that you did not have ventilation, I might have some other thoughts. That said, here is a short video on this subject that I think you will want to watch: https://www.youtube.com/watch?v=pEWcwNg29Ag&t=87s&list=PLMw9xVe_yEaVt4yv1i4LoDTlNKNd6boRd&index=31 Fastener spacing will be determined by your roofing manufacturer. It sounds like you plan a roof with exposed fasteners. Fastener location will also be specified by the roofing manufacturer but usually will be in the flat areas of the panels -- not on nor in the ribs. Keep in mind that, if you chose a concealed fastened standing seam, then you would also be able not avoid exposed fasteners for your solar panels.
Guest User
4/1/2017
Hi Todd, Many thanks for the reply. You are the first person to give me a reasoned explanation for your recommendation!
James Knight
5/3/2017
Hi Todd, I am a first time user on this site......nice to meet you. I am attempting to slate a new roof on a newly built CHICKEN COOP (yes). My question is: do I need to use battens to nail the slate to. Most of what I've seen with some of the large companies is that they do not use the battens. My roof is not large at all. It is just 120 sq. ft. Do I really need battens? Please advise. Regards, James J Knight
Todd Miller
Isaiah Industries, Inc.
5/3/2017
Thanks James. So, is it a metal roof you're installing? Do you have plywood or some sort of decking down or not?
James Knight
5/3/2017
No Todd, it is not a metal roof. It is a slate roof. Using 16x9 inch slates. I read a comment you sent back to Chilly Canuck regarding battens. My reason for thinking that perhaps you could guide me in that respect.
James Knight
5/3/2017
Todd, Regarding the decking.....yes, I have 1/2 inch plywood down. James Knight
Todd Miller
Isaiah Industries, Inc.
5/3/2017
James, thanks. I am really not a slate expert but I think that slate would be best if installed over the plywood without battens. These folks should be able to help you: https://slateassociation.org

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