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TOPIC: Roof Pitch

Metal roof panels on low slope

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I live in the snowbelt outside of Buffalo, NY and have a 50 year old "contemporary" house with a roof that has very little slope - approximately 1" rise for each 12" of roof. The rafters are exposed (inside the house) steel. The original roof was asphalt, but later was re-roofed with 22 foot long by 3 foot wide corregated vertical metal panels. These panels were not overlapped by much and have no standing seam - just screwed down and probably some roofing cement applied at the seams. We experience leakage every winter along the entire low side of the roof. There is very little insulation in the ceiling (4" of Insulrock or "tectum"), so we also always have long icicles on the low side of the house, indicating heat loss. I would like to tear-off the old metal roof, anchor 2" X 12" wood rafters on top of the steel, fill the bottom 6-8" of the new space with rigid insulation, and then apply plywood decking, a moisture barrier, and a standing seam metal roof. The plan will include provision of a ventilation system between the insulation and the plywood decking. This approach should provide both insulation and ventilation. Question to you is: can I safely apply a metal roof to a house with such low pitch? Do I need more than the usual amount of ice-guard as an underlayment? Thanks. Dick Linn
Guest User

4/20/2003
Overall, what you're planning sounds very well thought out. Have you considered having a structural engineer review this to verify the building can handle the weight, etc? It might be an excellent way to spend $2 - 300. Have you considered raising the pitch of the roof while you're doing this? Yes, it will change the look of the house but it might be a good way to a trouble free roof. To the best of my knowledge, the only standing seam roofs which can be used as low as a 1:12 pitch are roof panels which are "field-seamed," meaning that a seaming machine is run down the joining lap between panels after they are installed for the purpose of making the seam watertight. This type of roof is commonly used on idustrial buildings. I suggest contacting individual standing seam manufacturers and inquiring with them. Good luck. Todd Miller
Todd Miller
Isaiah Industries, Inc.

4/21/2003
Mr. Lynn, You are certainly doing you homework. I would recommend the use of a mechanically seamed standing seam roof on such a low pitch. This will insure a trouble free roof. Although the coorugated type, through-fastened roofs have throughout the years been used on such low slopes, (and have been done successfully) I would rather have something that can withstand a flood of water over the seam. I agree with Todd about having an engineer review your loading before you begin.
Guest User

4/25/2003