Preping old home for metal roof install

Guest User
12/8/2004
I just purchased an older (1930) cottage. I am considering replacing the roof with metal. Right now it has 4 layers of shingles. Right now I am working on the inside of the house, and will replace the outside in the spring. I just want to make sure I get the inside right. The ceilings in the upstairs closets follow the roofline (the ceiling slopes with the roof, no attic in closets. The rest of the upstairs has an attic.) The closet ceilings have major water damage. I began to pull them down to replace, and there is allot of moisture, mildew, etc. There was no vapor barrier, and in some places no Sheetrock, just exposed insulation. Because of the moisture, some of the boards on the roof are dry rotted. So, in the spring these will have to be replaced. Can I finish the inside of the closet ceiling now knowing I will have to replace the outside boards? If I replace shingles with metal, do I still need to run air battens, then insulate, then vapor barrier and Sheetrock, or can I just hot pack it? I live in the upper Midwest so we get alot of cold and snow. The closets however are not heated, (only heat from surrounding rooms). The other problem with the air battens is that the roof joists are 24" on center. They then have 2x4 supports running horizontally between them. How would I run the battens? Whould I tear out the horizontal supports? Drill holes through them for air flow? Again, can I just hot pack if I'm using a metal roof? If metal is lighter, can I just rip off the shingles and put plywood directly over the existing boards and not worry about weight? I'm conserned if I finish the interior, run the battens, then replace the exterior boards in the spring, I will destroy the battens in the process. Sorry for the long note and all the questions. Your help is much appreciated. MS.
Allan Reid
Dura-Loc Roofing Systems, Inc.
12/9/2004
In one breath you are wanting to do it right but in the other you are in a rush and want to work from the inside out. Also I am unsure what you mean about the term "Hot Pack". When the cottage was built in th 30's it would not have been insulated and relied on the roof to breathe and exhaust the moist air. All the changes since then have made the situation worse. I would strongly suggest working from the outside in. All those layes of shingles are weighing the roof structure down and trapping moisture from heat loss. The dry rot needs to be addressed. It will go dormant if you dry it out but never goes away and can quickly come back to life years latter with moisture. It needs to be removed. Replace the bad ones and minor ones can be scrapped, then have it sprayed with formaldahyde. I would resheet the entire roof so that it adds strength and acts as a separator between the roof covering and insulation. The roof needs to be ventilated properly so I would install an eave/fascia intake vent detail, lay a good quality underlayment as a moisyutre barrier and then strapthe roof vertically with 1 1/2" boards olayed over and fastened into the rafters. Now choose a metal roof system that is designed for installation on horizontal strapping. Check their product approval report. The problem now is with the upper attic space that nees to be vented. It should have intake air at the transition from the vaulted (sloped) ceilings and at the ridge. Probably a uniform row of pot type ventilators will work. Then cut the ridge open so there is a minimum of 1" air space through to the attic. Finally install a vented ridge system. This will allow the air from the eave to migrate up under the roof covering venting the lower sloped roof as well as an exhaust for the upper attic. Now you can go inside and remove all the ceilings and existing insulation. Install new insulation, an air barrier such as 10 mil poly (make sure you seal all joints and penetrations with tape or caulking) and then install you finishes and you will enjoy a comfortable space for years to come. Don't forget to choose an energy star product if you want to save on Air conditioning costs. We have some products that self ventilate and work well on this type of instalation. Check them out at www.duraloc.com. Good luck.
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