Rake Edge/Eave Edge for Vertical Panels

Guest User
3/2/2005
I've noticed that many (all?) vertical panel manufacturers have rather complicated-looking profiles for their eave and rake edging. I can see why this is for the rake edging - it needs to hold the edge down against wind, and wind-driven rain infiltration as well as hide a potentially ugly-looking cut edge if the panel width has been trimmed to fit. It's the eave, or drip, edge that's got me stumped. Unlike composition shingles, metal roofing panels won't sag if extended out from the eave an inch or two. Furthermore, "closures" are supposed to be used to fill the spaces between the panel ribbing and the roof decking. I just don't see why regular old galvanized L-flashing or drip edge can't be used with PBR/Rib/5V/etc. panels?! The cost difference is staggering: a local supplier here, whose panel prices are very good, nonetheless charges $1.45 per linear foot for drip edge for PBR panel; The price of a 10' section of 4"x5" galvanized L-flashing at Home Depot is only $7 while a 10' section of 2"x3" drip edge is only $3.80. This is a spread of 2x to 4x in cost, so I feel like I must be missing something here??? Can anyone shed some light on this for me? Regards, Jeff
Allan Reid
Dura-Loc Roofing Systems, Inc.
3/2/2005
As a association we are limited in discussions on costing. I can however discuss technical details. The building code states that all roofing must have a drip edge which stops water from running back under the edge uphill. Yes water will run uphill through syphoning, capillary action and surface tensioning. A metal drip edge is most common with most roofing products especially asphalt shingles. It has a couple of speed bumps on the top side to break the water movement uphill and a lead edge of about 45 degrees to force water to drip. It also helps hold the shingle in place against wind. Vertical rib metal is no differant in that water will run up hill under the roof sheets. A metal drip edge is required on roofs under a 45 degree angle and a sealing strip either a closure or butyl tape to stop the water action. In certain cases such as vaulted ceilings, the building code requires that a min of 1" in the US and 1.5" in Canada of vented free air space be provided under the covering. Vented closure strip will resolve this at bottom and top. Ask to see the ICC product approval report on the roofing product you choose which will state how the roof has been tested and proper instructions to install it and indicate whether it is an utility grade product for agricultural or high quality for residential. Remember you are putting on a lifetime roof.
Guest User
3/2/2005
You're right Jeff, accesories such as drip edge are expensive, especially when most times drip edge is hidden by the gutter. I do one of two things. 1, I purchase coil stock in the same color, and bend my own. 2, I order extra panels, and again bend my own from vertical rip cuts off the panels. I always add a kicked out hem on both of these applications. Both of these procedures also assure that I have the proper angle to accomodate the roof pitch. If you have the proper bender (a max2000 or equivalent), and a little time, you can manufacture all of your own components as well. I recently received a quote from another fabricator for components of $4100.00 for a 55 sq dutch seam roof. I bent my own, and saved $2900.00 on one job. This will more than pay for a quality bending machine.
Todd Miller
Classic Products, Inc.
3/2/2005
As a manufacturer of some standing seam, we have found that an eave detail which allows for locking over the bototm edge of the roof panels, including allowance for expansion and contraction, can help considerably with uplift resistance in high winds.
Guest User
3/3/2005
Thanks for the replys so far - I hope to make this a "lively" discussion ;) I'm not questioning the need for drip and rake edge by any means, rather, I am concerned about the high relative cost of these for metal roofs as compared to those for shingled ones. I understand that the MRA can't comment on specific pricing which is why I am discussing this in a relative fashion with "no names named." My objective with this post is to learn why drip/rake edge is so expensive for metal roofs as well as, perhaps, encourage a manufacturer's rep to defend this price disparity... :) Let's compare apples to pomegranates, so to speak: two 5' x 20' rectangular roofs of 1000 square feet area and 50 linear feet perimeter. One is covered with GAF Timberline 30 shingles while the other is clad with 26ga. plain Galvalume PBR panel. We'll assume for the sake of argument that underlayment, decking, and fastener costs are the same (though for the metal roof that is certainly *not* true: each neoprene-gasketed screw typically costs 15 cents while each 1.25" roofing nail on a coil costs 0.35 cents!) The premium GAF shingles cost $52 a square here in Tampa, FL these days while one manufacturer of metal roofing with a usable web site quoted a cost of $72 per square for the PBR panel. Total costs for the actual roof coverings, then, are $520 and $720, respectively. The shingled roof can use 1.5" x 1.5" galvanized drip edge on both the rakes and eaves. This flashing costs $1.97 per 10' length at Home Depot for a total cost of $9.85. The metal roofing manufacturer specifies different profiles for the rake and eave, costing $31.00 and $19.75 per 10'2" section, respectively. The total cost here is a staggering $110?! ((1 x $31) + (4 x $19.75)). The edge treatment for the metal roof costs over 11x more than that for the shingled roof, and constitutes 13% of the materials cost. In stark contrast, the edge treatment for the shingle roof constitutes 1.8% of the materials cost. Now, I understand well the argument for needing a special profile at the *rake*, but I really don't see why a metal roof would require a special profile at the eave?! The distance water can travel via capillary action is inversely proportional to the narrowness of the gap between two surfaces (among other things) but, nevertheless, overhanging the panels 1" and using inside closure to seal the gaps between panel and deck should absolutely stop any water ingress; I don't see how drip edge would improve upon this... Frankly, metal roofing resembles the inkjet printer pricing model: sure the printers (panels) are cheap, but what kills you is the ink (drip/rake edge)! Basically, I'd love to hear a manufacturer explain why the special drip edge is needed at the eave without resorting to "it voids the panel warranty if you don't" as the main/only reason! Any takers?? ;)
Todd Miller
Classic Products, Inc.
3/3/2005
You've gotten a lot further into pricing than I can possibly talk about here; in fact, I am going to try to edit out your prices so that I can keep your post and not delete it. However, my company requires interlocking starters far different from normal drip edges. This is to secure the bottom edge of the roof panels. Additionally, the coatings used on most metal roofing trims are considerably higher quality than those used on generic drip edges, and the metal is thicker. These all increase costs. Additionally, many times, metal roof system components must be custom-made on pressbrake in order to accomplish specific pitches and even profiles. The generic drip edges used with conventional shingles are all rollformed on a high speed high volume basis. All that said, you need to psoe this question to the manufacturer you're talking to. I would also really urge you to contact some MRA member manufacturers.
Guest User
3/3/2005
I did call up one of your member manufacturer's today, SEMCO, and spoke with an extremely helpful man there in technical support. He told me the main reason you have to use a special drip edge is not because of its profile, but because of it's metal composition. Presumably, then, Galvalume sheets must be used with Galvalume drip edge while only galvanized sheets can be used with plain vanilla drip edge. This sounds pretty reasonable to me but I can't help but wonder (and forgot to ask!) whether those $0.15 apiece screws are *Galvalume* or just plain galvanized?!?! My money says they are simply hot-dipped galvanized! I'd call the guy back right now and ask him but I think he deserves a break after dealing with a nitpicker like me.
Allan Reid
Dura-Loc Roofing Systems, Inc.
3/4/2005
To the best of my knowledge they do not make Galvalume screws. Most are zince plated. There are much better ones of stainless or stainless heads on zinc plated shanks. The ICC product approval on the profile you choose should indicate what fasteners that the system was tested with. Good luck.
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