[Greenbuilding] glass panels as porch roof?

[RT]

The glass requires 1/2" bearing on the support framing  + 1/4 "edge  
clearance to allow for expansion.

Allowing 1" width for the clamping bar fastening arrangement the total  
width for two glass panels is 2.5".

For a porch roof, normal, nominal 2x framing lumber is fine for the  
rafters. (ie 2x6, 2x8 etc depending upon specific span and load conditions.

One simply needs to attach a 1x3 (ie 3/4" x 2.5") to the top edge of the  
rafter to create a "T" cross-section member.

The 1x3 provides the necessary 2.5" width for the bearing , as well as  
lateral stiffening for the 1.5" dimension of the rafter. while at the same  
time minimising the shadow cast by the framing member.

Standard steel stud framing channel runner will serve as a water-proof cap  
for the support framing member and standard "J" trim can be inserted under  
the edges of the upside down channel to function as condensation gutters.

I have lots of EPDM roof membrane around that it's easy to slice off  
strips from to place on top of the metal cap on which the glass can rest  
and be free to move. Some double-faced tape can be used to adhere it.

Standard aluminum clapping bars are typically a minimum of $# per lineal  
foot .  I find it more economical to simply use beveled-edge wood battens  
as clamping bars and bend a sheet metal cap to snap over it, milling a  
dado into the batten to accept 6mm neoprene screen spline which functions  
as a pressure gasket.

This provides a basic outline of the process (effectiveness proven by  
decades-worth of trouble-free service) but I've obviously left out many  
details. Not rocket science to figure out on one's own.


On Fri, 19 Sep 2014 15:27:27 -0400, Reuben Deumling <9watts at gmail.com>  
wrote:

> Laren,this method sounds great. I'm going to give it a try.

> That is to lay
> the glass on top of the rafters (ideally beams, so they
> have adequate width for lap and movement)
-- 
=== * ===
Rob Tom . . . T60BOM
Kanata, Ontario, Canada

A r c h i L o g i c at Y a h o o dot C A
(manually winnow the chaff from my edress if you hit "reply")
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