roof glazing

[pike]

hi, could anyone tell me how this sort of glazing would be done?

do you have to seal the glass?

i'm wondering if there are rubber strips under the "battens".

also it looks like a lot of weight to put on one bottom holder if it isn't gripped any other way?

thanks!

 

[9fingers]

Almost certainly will rely on the run off to stop water coming in plus the gradual build-up of dirt to seal.

Glass retention should be OK as at this low angle, most of the weight of the glass will have a vertical component and only a small force in the plane of the glass to make it want to slide out.
Also allows wood to move with the humidity.
I'm guessing this is a budget design based on greenhouse construction.
My concern would be the snow loading on the frame.

I would expect a better design to include glazing beads and seals but then there would be the problem of getting up there to fit them.

Bob

 

[Martingchapman]

The bottom picture looks like my Alton Cedar Greenhouse.
There is a slot across the top and down both sides of the frame.
The glass simply slides into the two side slots and is pushed into the top slot.
You then screw a plastic clip on the bottom frame member to stop the glass sliding out again.

Seems to work fine on my greenhouse, no leaks and no rattles.

Martin.

 

[pike]

thanks for the info much appreciated.

Some of the lean-to's I'm looking at have 8 foot long panes of glass using the design from the last photo (as far as I can tell).

Bob: I see that provided the pitch isn't steep the weight is going down too, thanks. The glass would be tough, but the issue of snow is a good point. At present I have no idea what the load of a 24 inch wide 7 or 8 foot long pane of say 5mm safety glass would be. It is a greenhouse budget style project. Do you mean snow loading on the frame, or the glass? The framing would be 2 x 6.

The other option I'm considering is aluminium capping with rubber gripping. Better maintenance but less pleasing for me.

Martin: thanks. as above I'm wondering if this is suitable for a lean-to with heading onto 8 foot long panes.

 

[9fingers]

Pike,

The whole structure has got to carry the snow load. Worst case for snow is not the soft fluffy stuff when it first falls but when the thaw-freeze-thaw-freeze cycle starts in a bad winter and you can end up with a few inches of ice.

This may help http://doctor-roof.co.uk/?m=200905 and there is possibly something in the building regs website maybe with regional variations.

I'm assuming this is a commercial product you are considering and so there should be a loading specification available from the manufacturers.

hth

Bob

 

[Martingchapman]

Pike,

Take a look at the Alton lean to greenhouse at the bottom of this page;
http://www.altongreenhouses.co.uk/index.php/greenhouses/traditional-collection

They only have one size which is 5ft wide, probably means the glass is about 6ft long, not quite as long as you are planning.

Take a look here at another Alton lean to;
http://www.altongreenhouses.co.uk/index.php/greenhouses/amateur-lean-to/109
Where there is a 7ft wide lean to which probably has 8ft long glass.

All their glass is toughened.

Not sure if this helps or not.

Martin.

 

[pike]

Thanks Martin. Their assembly instructions are interesting.

 

[Martingchapman]

I have the 6ft x 8ft Octagonal and it went together just as it says in the instructions, no problems at all.

Martin.

 

[MikeG.]

Glass is usually retained in these circumstances by a folded piece of metal clipping the bottom edge back to the timber....in much the same sort of way as a tingle holds a slate.

It can be done in zinc, copper, stainless steel and probably many other materials, but avoid galv. mild steel as the bending and unbending of the clip around the bottom edge of the glass will break the galvanising. I have seen it done in lead, but wouldn't be quite so confident of that.

It isn't dirt that seals the sides of these!!

In the old days, of course, it would have been puttied in, but now it can be a silicon product, or one of the glazing tapes.

Mike

 

[pike]

thanks Bob, I'm looking at a commercial product and also wondering if I would be wise to take on building the lean to myself, after a lot of r & d.

Mike, I am guessing that by glazing tape I could also say glazing foam. A sort of thick lining which goes either side of the glass keeping it out of contact with the wood and sealing it.

 

[GraemeM]

I built a load of cold frames for a client. Very simple frame with the bottom just as per your pictures illustrated below the line of the rebate for the glass and s top block.

But the one thing I would recommend is using exterior grade acrylic (not plexiglass which is an expensive brand). Its very much lighter than glass, tough so no problems with footballs, snow, dropping the frame etc. I went for quite thick, 7mm if I remember correctly. It may not be as cheap as 3mm glass, but then I think you were thinking about thicker glass anyway. The main things is seek out a plastics/acrylic provider who will cut it and sell it at a reasonable price. There were quite a few providers on the net who quote prices so you dont have to pay B&Q prices.

Good luck.

 

[pike]

Thanks Graeme, that does sound like a good alternative to glass (provided it has UV protection). I might get one of each and see what I think as opinions seem to vary in which is best for a greenhouse.