SB: RE: re: metal roofing

[jmark.vanscoter@amd.com]

I had a metal-covered pole barn/shop built when I lived in Indiana. Never got so back that it "rained" inside, but the condensation often dripped down on humid days.

 

My take on the metal roof directly over the purlins is that it is a solution if:

1. You live in a very arid area.

2. The building is for storage only.

3. There will be no insulation on the roof.

 

For me. the solution on the structure I plan to build in December is to deck the roof with 1/2" CDX. Then, cover with felt-paper (tarpaper) and build a grid on top of the decking with 3/4" stock (cut up plywood?) going over the trusses and other ones going on top of the built-up trusses but going left to right, two feet apart for nailers. This still gives you the gridwork so walking on the roof is possible, without the condensation problem.

 

That way, the felt-paper minimizes the opportunity for water to leak inside, air can circulate under the roofing keeping the inside cooler in hot weather and minimizing condensation in cool weather. All this should keep everything fine. May seem like a lot of work, but I want a 50 year roof.

 

Mark V.S. in Austin, TX

-----Original Message-----
From: N Leone [mailto:nlpub@hotmail.com]

Howdy all,

 

Rob Tom mentioned that metal roofing can be attached directly to purlins, thereby eliminating a lot of roof decking while giving you something to grab on your way off the roof.  Sounds like a good idea to me.

 

So, what's the question? you may ask.  (Or maybe you wouldn't...)  My question is this:  I have heard that the underside of the metal can attract condensation that might then drip down onto your ceiling insulation bales.  (OK that's not really a question, it's a statement.  Here's the question:)  Has anyone experienced that type of problem?  If so (or even if it seems a reasonable concern), any ideas on work-arounds?  My brother the sometimes SB builder,  bread baker, and aspiring masonry stove mason suggested tacking 30# roofing paper to the purlins, but he also acknowledged that that could make putting the metal up a bit more challenging.  (Goodluck not stepping through the stuff.  And goodbye hand, foot, leg, nose, etc. holds... )

 

Thoughts?