I've never had that luxury, generally the underside is visible and can't be changed. We get through but it's a pain.
On Wed, Jul 4, 2012 at 8:36 PM, benn kilburn <b...@daystarsolar.ca> wrote: > Chris, > I'm pretty sure that what David means by "blocking" is if the roof has > rafters (peak to eave) rather than purlins (horizontal) then, IF you can > access the underside of the roof, you properly install 'blocking' (2x4, > 2x6, 2x8) against the underside of the roof sheathing, perpendicular to the > rafters. Then you can drill your bolt anywhere along the blocking which > then eliminates the restriction of having to attach to a rafter every > 16-24". Keep in mind that there are proper methods of doing this to make > sure the blocking is properly attached to the rafters, otherwise any uplift > pressure from the array is only supported by the roof material and not the > structure (rafters/purlins) > > Then again, access to the underside of the roof is not always available or > is restrictive, so this is an important factor to figure out before you > land on site with your roof attachments and racking, ready to go. > > Cheers, > benn > > DayStar Renewable Energy Inc. > www.daystarsolar.ca > 780-906-7807 > Construction Electrician Solar Photovoltaic Systems Certified > Certificate # 0007S > HAVE A SUNNY DAY > > On 04/07/12 5:23 PM, "Chris Mason" <cometenergysyst...@gmail.com> wrote: > > I use corrugated mounting bridges - that's the problem. If the center of > the beam falls in the trough, the corrugated bridge is useless. > I am not sure how blocking would help. Corrugated is a pain. > > > > On Wed, Jul 4, 2012 at 12:11 PM, David Brearley < > david.brear...@solarprofessional.com> wrote: > >> In some cases, you can install blocking to get up on the ridge >> consistently. One alternative to hangar bolts is to use corrugated mounting >> bridges from DPW Solar or something similar from another company. >> >> Sorry I can't link to the PDF. Google: "corrugated mounting bridges" >> >> Since exposed-fastener metal roofs already have a bunch of holes in them, >> you're not voiding the roof warranty by punching more holes in the ridge. >> (I don't think these roofs even meet the NRCA definition of a "roof >> assembly" because of the exposed penetrations.) Penetrations in the valleys >> on a roof are problematic for obvious reasons. >> >> >> On Jul 4, 2012, at 6:01 AM, Chris Mason wrote: >> >> > All of this refers to shingle roofs, which we don't see much of. We >> mostly deal with concrete and corrugated steel/galvalume, the latter being >> a nightmare. Does anyone have good ideas for dealing with corrugated? >> There's no way to flash it, the blocks are fine when you hit a beam on the >> ridge but half the time your penetration has to be on the trough of the >> corrugated steel. >> > Other than lots of goop, I don't know how else to seal it. >> > > _______________________________________________ > List sponsored by Home Power magazine > > List Address: RE-wrenches@lists.re-wrenches.org > > Options & settings: > http://lists.re-wrenches.org/options.cgi/re-wrenches-re-wrenches.org > > List-Archive: > http://lists.re-wrenches.org/pipermail/re-wrenches-re-wrenches.org > > List rules & etiquette: > www.re-wrenches.org/etiquette.htm > > Check out participant bios: > www.members.re-wrenches.org > > > -- Chris Mason President, Comet Systems Ltd www.cometenergysystems.com Cell: 264.235.5670 Skype: netconcepts
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