[Greenbuilding] glass panels as porch roof?

[Reuben Deumling]

Laren,
this method sounds great. I'm going to give it a try. The *Ice and Water
Shield* product I'm finding is wide. Can I use flashing tape used for
windows instead? I have that, and it is already much closer in width to
what I need.

Or do you use a product more closely sized to what we're talking about
here?

Thanks.

On Wed, May 7, 2014 at 3:29 PM, LarenCorie <larencorie at axilar.net> wrote:

> From: "Michael O'Brien" <obrien at hevanet.com>
>
>  I would like to encourage you to set the glass panels in
>> gaskets or flexible blocks that would hold securely, yet
>> allow the glass to expand and contract with temperature
>> changes.
>>
>
> Hi Michael;
>
> Your priorities are right on. However, in this case, there
> is a simpler way to mount the glass that is easier, more
> durable, and also a lot more water tight.  That is to lay
> the glass on top of the rafters (ideally beams, so they
> have adequate width for lap and movement) with a
> stop, only at the bottom.    If there is foam insulation
> available, about the thickness of the glass compressed
> (or slightly thinner), cur it to bring the rest of the area
> up to level with the plane of the face of the glass. Leave
> a very small gap between the foam and glass edges.
> Only minimal is needed, for movement, since the foam
> will flex. Once the whole plane (roof around the glazing,
> in this case) is level, cut strips of Ice & Water Shield, or equivalent,
> to cover all non-skylight areas. It should
> overlap the glass as much as possible, without being
> visible from below/inside (or just a nice straight edge,
> barely visible).        Get a smooth piece of wood (or
> comparable) and use it to burnish the I&W shield
> where it bonds to the glass, to make sure that all
> the air bubbles, and crease lines are rubbed out.
> Battens can then be installed over the edges of
> the glass (keep screws and nails away from the
> glass edges). Wood battens tend to cup, so I
> recommend batten material that will not, such
> as fiber cement boards.
>
>   Detailing for the lower end of the glass is significantly
> trickier than described above. It is highly advantageous
> to avoid creating a gutter that would accumulate leaves,
> and other roof dirt/debris.    Ideally, you want the glass
> to slightly overhang the wall, or most outward structure
> (even a fairly conventional eave) so that water running
> off it, will fall outside the structure.   I have often used
> an aluminum angle with a short leg, about the same length as the thickness
> of the glass. No cap or batten
> covers the glass along this edge. Just fill any gaps with a quality
> silicone sealant.     Water and debris
> should freely slide off the edge of the glass roof.
> I did quite a few of these, back in the early 1980s,
> with design details to control overheating, and even
> used it to heat the domestic hot water.       If it has
> potential for Summer overheating, why not use that
> heat?  Under such a roof can be a pretty good place
> for a batch water heater.
>
>> With big panels it's a significant issue, because if the
>> glass expands in a frame that can't flex and causes
>> pressure on along its edges, it might fracture.
>>
>
> That is why it makes no sense to create rabbets to set
> the glass down into a place where it could get pinched.
>
>  If you look at a cross-section of a commercial glazing
>> system you can see elastic gaskets between the glass
>> and frame.
>>
>
>   Standard glazing tape does a very poor job at sealing
> site-built glass roofs. The problem is that, because it only
> seals the tiny distance between the glass face and a stop
> or batten, it lacks the ability to bridge gaps that increase
> by more than about 1/16", whereas the taping system
> I described, can remain weatherproof, even if the
> glass, were to moves an inch or more.
>
> -Laren Corie-
> Natural Solar Building Design and
> Solar Heating/Natural Cooling/Energy
> Efficiency Consultation Since 1975
> www.ThermalAttic.com  (many new
> photos and pages, coming soon)
>
> Read my Solar house design articles in:
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>
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