[RE-wrenches] to flash or not to flash

Ray Walters ray at solarray.com
Fri Aug 7 13:55:59 PDT 2015


Hi William;

I agree with the overlapping roof elements concept, as I mentioned in my 
previous post.  However in many cases, (metal roofs for instance) the 
flashing can not be overlapped as you described, and is sealed with 
adhesive.  It is still called a flashing, and is still acceptable to 
roofers.


R.Ray Walters
CTO, Solarray, Inc
Nabcep Certified PV Installer,
Licensed Master Electrician
Solar Design Engineer
303 505-8760

On 8/7/2015 12:19 PM, William Miller wrote:
>
> Ray:
>
> I have to respectfully disagree with your semantics.  A flashing is an 
> overlapping of roofing materials such that gravity will direct rain 
> and melt water off of the roof. This is a universally accepted 
> waterproofing method that does not depend on any sealant material.  
> The concept is as ancient as the first, crude, thatched roof.
>
> If you place a flat object on top of roofing without an uphill 
> material lapping over the downhill object, you are not flashing.
>
> What you have described is sealant-dependent weatherproofing. 
> Regardless of the quality of the sealant, or lack thereof, I don’t 
> think you can call it a flashed attachment.
>
> (The overarching point is a flashed attachment does not depend on a 
> sealant.  Any sealant has a finite lifespan.  Removing the sealant 
> variable from the equation results in more lasting installation.)
>
> Sincerely,
>
> William Miller
>
> Gradient Cap_mini
> Lic 773985
> millersolar.com <http://www.millersolar.com/>
> 805-438-5600
>
> *From:*RE-wrenches [mailto:re-wrenches-bounces at lists.re-wrenches.org] 
> *On Behalf Of *Ray Walters
> *Sent:* Friday, August 07, 2015 10:34 AM
> *To:* RE-wrenches
> *Subject:* Re: [RE-wrenches] to flash or not to flash
>
> My opinion is that if the L foot has enough surface area it 
> constitutes a flashing, and that large flashings can actually cause 
> more damage to the roof than they prevent.
> I also agree that an attachement doesn't constitute a penetration.  I 
> just finished an install on a metal roof with hundreds of screw 
> holes.  We added a few more screw holes, and ours have 20 times the 
> sealant surface area.  We did run a 1" conduit through the roof, and 
> since it was an actual penetration, we used a very expensive flexible 
> boot flashing.
> Personally, I think we need about a 3"x3" or 4" x 4" L foot with a 
> double stick butyl tape on the bottom, and all will be well.
> I realize that the OP was referring to asphalt, but I will flash other 
> roof types that don't do well with L feet ( like shake).
>
>
>
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