Installation with an exposed ceiling: "Gentlemen, I come seeking some advice about replacing my asphalt ..." - Guest User (2/2/2004) | Roofing over existing roof | Archive

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Gentlemen, I come seeking some advice about replacing my asphalt shingle roof with a standing seam metal roof. The particulars: A 3-season vacation home in southern Maine, built by my family in 1969, with the original asphalt shingle roof. Existing roof is sound, but showing its age. Neighbors with homes of similar vintage, built by the same developer, are replacing their roofs, usually with asphalt. House is 24x32, chalet style, 12-inch pitch, with half loft. Roof is constructed on 4x12 beams, 4 feet on center. Substrate is tongue and groove 5/4" x 4" knotty pine, exposed throughout the house. Above the tongue and grove pine is a layer of insulation board, probably polystyrene, possibly as much as 3 inches thick (none is exposed, so its hard to tell). Original asphalt shingles are attached such that no nails come through the 1x4 tongue and groove pine into the interior of the house. Our only heat is a wood stove, used infrequently, since we are not there much in the fall. Stove is vented with a metal stove pipe, exposed throughout its rise in the “great room,” exiting the roof via a “metal-bestos” type chimney. One skylight through the roof, over the kitchen, about 2' wide by 4' long, installed about 10 years ago and in solid condition. Two 4-inch plumbing vent stacks go through the roof on opposite side of the house. The half loft serves as the “master suite” and we enjoy the view of the tongue and groove ceiling, as well as the gentle sound of rain on the roof. From the responses to other questions on your web site, I gather that a metal roof should not be noisier than the pleasant sound of rain on the current roof. My questions - 1. Is it going to be practical to install a standing seam metal roof over the existing asphalt without the need to put nails or screws through the knotty pine tongue and groove substrate (e.g., without ruining the look)? 2. Does the existing insulation board pose specific problems, or offer any advantages? 3. Is the relatively wide spacing of the beams likely to be an issue? Thank you for any advice you can offer. Harry	Guest User 2/2/2004	Share Or copy this URL: https://www.metalroofing.com/spirit/comment/2677/find/
Thanks for providing so much information and I am assuming that the one season it is not used is winter. With the steep slope and the insulation board I would strap the roof so that the entire roof system stays in place and does not tend to "slide down" as the isnsutaion will put a lot of stress on the fasteners. I would take the opportunity to install a vented air space to the new building codes at the same time which will provide a much more comfortable environment in the summer months. Choose a product and consult with the manufacturer however you should be able to meet the load requirements by strapping vertically over your 4x12 rafters with a minimum 1x4, fastened down through the insulation into the rafter. I would install a good quality underlayment over this and than the roof could be strapped horizontally with 2x4's at the mfg suggested centres. Then provide a vented eaves and ridge. It sounds like the sklight is lower down in the roof so ensure that it has a high enough curb as water running off painted steel will have more speed than off an asphalt shingle. Hope this helps.	Allan Reid Dura-Loc Roofing Systems, Inc. 2/3/2004	Share Or copy this URL: https://www.metalroofing.com/spirit/comment/2678/find/
Allan, Thank you for the advice. Yes, winter is the one season in which the house gets little use. We are on an island, served by a ferry that stops running from November to late April. The lake is currently well enough frozen that we could walk across, and have done so occasionlly over the years. Of course, we have no running water in the winter, which makes long stays a challenge! If I understand your suggestion, we would run 1x4 straps up the roof postioned over the exisiting beams. Then we run 2x4s perpendicular to the 1x4s to provide an air space and support the metal roofing. Are you also suggesting an underlayment, assuming that we strip off the current asphalt shingles? If we leave the exsiting shingles in place, will an underlayment help? Thanks for the warning about the skylight! It is 2/3s of the way down the roof from the peak, so I can imagine that the water would run down pretty quickly. Would a "cricket" above the skylight help too? Or would the seam on the cricket not likely be high enough itself to prevent problems? Fortunately, we don't have a large heat problem from the roof even in the summer. A much bigger concern is the west-facing wall of windows that provide spectacular views of the lake and mountains. However, shades and curtains make that manageable. Thanks again! Harry	Guest User 2/11/2004	Share Or copy this URL: https://www.metalroofing.com/spirit/comment/2679/find/