Reglazing an old, very large wooden greenhouse

[paeony]

We are in the process of repairing an old wooden market garden size greenhouse, 80'x15'. We need to replace some of the rotten rafters and reglaze large areas using the glass that is already there. Some of the existing glass has been fixed in place using silicone, but this detaches from the wood on the outside, allowing water to seep in. We need a better solution so that the greenhouse will remain trouble free for a good many years after all our hard work!
Be grateful for any ideas.

 

[merlin50]

putty

 

[Burnerman]

For the traditional type timber framed greenhouse, traditional methods are best.
This involves removing the old glass panes, and scraping away any old back putty with a broad chisel. With the timber dry, apply some new backing putty for timber (available in mastic type tubes these days if you want) and press the glass back in firmly, rubbing hard where the edges contact the timber frame. Secure the glass panes with a few small headless nails called sprigs, and then its either more putty with a chamfered edge (not so easy without loads of practice) or nailing on some timber glass beads.
John

 

[paeony]

thanks. John. I like putty but it is my experience that in too short a time it dries out and cracks, letting the rain through, and wetting the timber. It is impossible to reach to the top of the greenhouse (being 10' from the eaves to the ridge). If it needs repairing again the whole row has to be taken out.
I was hoping for some new modern miracle!

 

[Burnerman]

Putty is still the best method for traditional timber sashes but silicone can be used, if its pressed well into the rebate and the timber is dry.
Like any other natural material, timber will deteriorate anyway if it not maintained - in your case varnished or treated with Sadolin or similar which is why glazing beads could be used here.
Access is always going to be an issue, but in the first instance the glazing would have started at one end with the glaziers inside the building, working to the other end as they go. As you seem to be having a total rebuild anyway, this is how it could be done.
Any other method would involve erecting a scaffold above the greenhouse, and working at it from above.
John

 

[paeony]

No modern miracle then! I f you bed the glass onto silicone would you run a bead of silicone down on the outside?

 

[Burnerman]

You could do, but the silicone would have to be smoothed down with a finger....straight out of the gun and it wouldn't stick.
Personally I'd go for timber glass beads and a good treatment of Sadolin stain / wood preservative. I've used this stuff on my home and although I agree that the frames aren't constantly wet, the timber is still sound.
John

 

[paeony]

Thanks for the useful advice. Been cleaning panes of glass today. Dry weather at last!