Replies

1. 
   SCOTT_E._CHADBOURNE | Feb 22, 2000 09:46am | #1

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   1. vapor barriers normally are installed oriented to the
   heated side. Are you installing the purlins [sleepers?]
   directly on the trusses /rafters or on plywoood sheathing? PLYCO makes several vapor barriers and are sold through many lumberyards or any post frame [polebarn] supplier. PLYCO also distributes the butyl caulk in the roll you were advised to use. Use the tape if your pitch is less than a 3/12. If less than 3/12 you should be using a high rib of at least 1-1/4" tall. Siphoning is common on
   the laps with the low pitch necessitating the use of the butyl caulk tape. What brand of metal are you using and are you attaching it with screws or nails? When you install the
   metal make sure you get that first sheet square! A little trick to rip the metal {length way} is to use a pole barn
   nail or a heavy bladeed utility knife to score the metal as
   deep as you can with a pass or to. Bend the metal back and forth a couple of times and the metal will "break". Wear
   gloves as the edge will be sharp. If you use a power saw make sure that you flip the metal over so that metal sparks
   don't land on the painted surface as they will leave rust spots eventually. That urethane caulk is good stuff but it will eat your lunch to buy that amount. The butyl tape is economical and rolls out to make installation alot faster.

2. 
   Guest_ | Feb 23, 2000 01:50pm | #2

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   To reinforce Scott:

   Follow the manufacturer's instructions. If your lumberyard doesn't have what is needed get it somewhere else. This is important both for a satisfactory installation and to keep the warranty valid. Personally I prefer screws for metal roofing but some manufacturers allow either.

   Above the purlins/sleepers the roof is the "vapor barrier". Now if you want to add one on the heated side of the ceiling/roof under the insulation have at it. There are lots of diagrams on just how to do that. Several books, some from Taunton, give details and will help a lot.

3. 
   mark_kogler | Feb 23, 2000 01:51pm | #3

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   I am planning to install a 29-ga metal roof on my new 2-story garage/office. I am installing it on 2"x4" sleepers at 16" o.c. What type of vapor barrier should I use unser the roof, above the sleepers? The cavity under the sleepers is 9-1/4" and it will be insulated and finished with wallboard. Also, the manufacturer recommends a butyl tape along the seams. Mt roofing supply company has does not carry it. They recommend a urethane sealant. What do you think.