Josh Patterson
4/13/2005
Hi guys. I am new to this forum, so there already may be an answer to this question, but I'm going to ask it anyway. I am in the process of building a new house. I want a metal roof on it. I have built many "pole-barns" in the past, so I've worked with metal before. If you ask 10 people in my area about this, you will get 10 answers! I want to use 29 ga. Galvalume, haven't decided on the color yet. Do I need to deck the house and put tar paper on first, not deck and just put lathe strips on, deck, tar paper, AND lathe strips, what? Also, where do I put the screws? On the "rib", beside the rib, in the "flat" part, what? If I don't deck, will this have any effect on insulation? My house has a 12/12 pitch on the roof in most places, so there isn't any attic space in most areas. Other areas I do have some attic space, like dormers. Any advice will be gladly welcome! Thanks, Josh
Josh Patterson
4/13/2005
One more thing, I am in Northern Middle Tennessee. "tar paper" is felt paper. I am from Tennessee!! "Lathe strips" is the 2x4 or 1x4 strips that the metal screws to. Thanks again!
Allan Reid
Dura-Loc Roofing Systems, Inc.
4/13/2005
There are a number of things you need to consider in building a home that sets it apart from the ag buildings. First is the building code is differant. The roofing assembly as described in the building code consists of an interior air barrier. This should be a 10 mil poly with all the joints and penetrations sealed, especially around electrical boxes. This stops the warm moist air from migrating through to the outside and condensating. Next is there are certain insulation ratings required. Then it requires a moisture barrier between the roof covering and the insulation and generally a 30 lb fely is taken as minimum however you are installing a lifetime metal roof so you may want to upgrade the underlayment. Consider ice and water sheild in the valleys, along the eaves and around skylights and chimneys. The code calls for ventilation. For attic areas, it should be 1/150 ratio of free area to ceiling area and provided equally at the eave and ridge. For vaulted roof assemblies it requires a minimum of 1" and I would suggest 1.5" of vented air space under the roof covering. This will require you to strap the roof vertically and then horizontally. You can use vented profiled closure strips ay the eaves and under the ridge trim to accomodate this. Our association recommends using an AZ55 coating weight for exposed Galvalume roofing and I would also suggest stainless steel headed screws for best performance.
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