Why put decking under a metal roof?


  #1  
Old 02-25-04, 03:39 PM
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Why put decking under a metal roof?

I built a 22' x 26' carport about 10 years ago using homemade trusses on 4 foot centers, then crossed them perpendicularly with 2x4 treated lathes 24" o.c. I screwed the metal roofing directly to the lathes and, after 10 years, have no leaks, sags, rot, etc.

Now I'm in the process of building a 20' x 24' camphouse in the same manner, except that the trusses are on 24" centers. They are cross-braced diagonally underneath for stability.

Now for the stupid question. What is the purpose of decking if everyone puts lathes on top of the decking anyway? Is it just a surface for the vapor barrier? I've never had condensation problems on the carport (granted it is open air) and the environment around here (west of Houston) is extremely humid.
 
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Old 02-25-04, 05:53 PM
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There are 2 different types of metal roofs. One type is like yours, or like pole barns. Your 2x4's across your trusses, are similar to perlons, which the metal is attached to. The other type is like on houses, shops, quansets. These types do not have the perlons or 2x4's like you do. They lay down sheeting. They are a much stronger roof, and will last much longer. 40 to 50 years. If yours were enclosed, it would drip. Hope that answers your questions.
 
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Old 02-26-04, 02:48 AM
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Thanks!
Stupid question #2.
Let's say some moron (not me) has already done this. What can this moron (not me) do to correct it short of tearing the tin off?

.....before the moron's wife kills him......
 

Last edited by WFO; 02-26-04 at 04:37 AM.
 

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