Bill,
We called the company that manufacturers this product and were told not to use it on shingled roofs. They did not elaborate much more than that, and that warning was good enough for us to discontinue its use here. Of course, each is free to make their own determination as to its suitability for use Regards, Glenn From: Bill Brooks [mailto:[EMAIL PROTECTED] Sent: Monday, September 15, 2008 2:19 PM To: [EMAIL PROTECTED]; 'RE-wrenches' Subject: RE: [RE-wrenches] Stanchions for Comp Shingle Roofs Glenn and Peter, I just reviewed a few of the Technical Data sheets for Sikaflex and they do caution its use with asphalt shingles. They make the statement that these products should not be used in the presence of a product that might bleed oil. Of course the asphalt in shingles can bleed oil, but it will have this affect on all sealants other than tar. Tar does not have good adhesion to many materials, including aluminum, so I believe Sika is simply covering their buttocks. Alternatively, DAP has a nearly identical product that does recommend use on asphalt shingles. It is not substantially different and would still have the issues of bleeding oil. However, history tells us that these polyurethane caulks are exceptional in their durability on comp shingle roofs, so use the DAP product if you think the caulk manufacturer needs to backup the application. Bill. From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On Behalf Of Glenn Burt Sent: Monday, September 15, 2008 10:02 AM To: 'RE-wrenches' Subject: Re: [RE-wrenches] Stanchions for Comp Shingle Roofs Quick item on Approach #1 bares repeating Sika is incompatible with asphalt shingle roofing according to the manufacturer Regards, Glenn Burt Technical Specialist Renewable Power Systems, LLC PO Box 967 Averill Park, NY 12018 V: 518-674-5808 C: 518-810-3174 F: 518-514-1175 E: [EMAIL PROTECTED] www.RPSpower.com From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On Behalf Of Peter Parrish Sent: Monday, September 15, 2008 12:28 PM To: 'RE-wrenches' Subject: Re: [RE-wrenches] Stanchions for Comp Shingle Roofs Im not sure if we have discussed this before, but I would like to get opinions on the relative merits of the following two approaches to setting stanchions and flashing them in for a roof mounted PV system: Existing comp shingle roof in good condition. Professional Solar Fast-Jacks (or similar stanchions that result in a ¾ to 1 post to which to attach rails). I am not endorsing ProSolar products, I just wanted a specific example to work with. Approach #1: Lag stanchions directly onto existing comp shingle roof; cut a inverted U into the top layer of shingle; slip in Oatey-style flashing (9x12, with an elastomeric ring); seal exposed vertical edges of flashing with a bead of high quality caulk (Sika 1A) Approach #2: Remove shingles down to the felt; lag stanchion; replace shingles incorporating full-sized (15x18) flashing and seal top of flashing with high-quality caulk. Obviously, approach #2 takes longer and costs more, but does it confer commensurate benefit? If the resulting stanchion/flashing were exposed to the elements, I would tend to favor the latter approach; and if we were dealing with new construction the difference in time and money would not be significant. However, if the stanchion/flashing lies directly underneath a PV module, it will be shaded from the deleterious effects of UV sunlight and will not receive any direct rain or snow accumulation. Under these specific circumstances, I would argue that approach #1 should be more than adequate and last at least as long as an existing comp shingle roof. For those of you who havent seen the Fast-Jack/Oatey approach, you might want to look at http://www.prosolar.com/Oateys.htm. - Peter Peter T. Parrish, Ph.D., President California Solar Engineering, Inc. 820 Cynthia Ave., Los Angeles, CA 90065 Ph 323-258-8883, Mobile 323-839-6108, Fax 323-258-8885 CA Lic. 854779, NABCEP Cert. 031806-26 [EMAIL PROTECTED]
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