oil canning is a term used in the industry that denotes waviness in the flat area of a panel. There are many causes of this including the base metal, forming(equipment), installation practices. The biggest cause of oil canning is the structure itself. Unevenness in the plywood deck or bowing of the lumber will cause oil canning. On bright sunny days when the sun is low on the horizon is when we hear the greatest number of comments. Oil canning is strictly a cosmetic concern, although some owners prefer the looks of oil canning. There are ways of reduce oil canning; heavier gage, narrower seam spacing, stiffening ribs, stucco embossing.
A snap lock system installed with clips is the better vertical seam profile for your application. I would recommend that you only use products that are manufactured by a member of the Metal Roof Alliance as all the members have agreed to produce to a minimum standard.
Research the contractor and verify by calling other homeowners that he has done work for that he is a knowledgeable and reputable.
Dick Bus
2014-04-14 11:13:33.000000
. What is oil canning? Thanks again. Dick
Guest User
2014-04-14 10:43:20.000000
That is certainly a good option. As far as underlayment, I would suggest a synthetic product as well as ice and watershield as required by code. Hidden fasteners are probably best. If the home has flared gables where the ridge of the roof is wider than the bottom of the roof, that poses some extra challenges. You will want to make sure that your contractor has a way of doing that which will not trap ice, snow, and other debris.
If your roof has had shingles in the past, switching to standing seam will be a large aesthetic change. There are many metal shingle products you could consider as well.
As far as insulation ... adding extra insulation is never a bad idea.
Todd Miller
2014-04-13 22:35:27.000000
Those are fairly long panels but certainly not unusual. I would suggest a product that is secured with hidden clips rather than a through fastened or nail flange fastened product. Having the base you install over me as smooth and square as possible will help avoid ripples in the panels. Additionally, because of the steep pitch of an A Frame, you very much are looking into the panels so any oilcanning which may occur will be pretty visible.
Todd Miller
2014-04-14 08:37:50.000000
Thanks Dick. Also, if you scroll down this page a bit you will find a good technical bulletin on oil canning: http://www.metalconstruction.org/index.php/education/technical-resources
Todd Miller
2014-04-14 11:57:16.000000
My a-frame is about 30 ft from eave to ridge x 32 ft wide (each side). Decking is tongue and groove 2 x 6. The pitch is about 24/12 (very steep). 1. Is standing seam a good choice? 2. Are hidden fasteners ok? 3. Are 30 ft long (eve to ridge) panels best? 4. What underpayment is best assuming no additional insulation is desired? There is already 2 inch foam insulation on the interior of the house.
I would appreciate any comments or answers you may have for me. thanks. Dick6fu
Richard Moore
2014-04-13 22:29:02.000000
Thanks for the info, Todd. As a follow up, the roof is not flared so it would be a nice clean straight installation on both sides with a minimum of vents and thru-roof protrusions. Would 30 ft panels from eave-to-ridge cause and expansion problems? Thanks again. Dick92