Do we need mastic?

[muckdiva]

We are just about to put up the secondhand greenhouse we got via Freecycle. Thing is, it took ages to get the glass out when we took it apart as it had been fixed with mastic and we did manage to break a few panes along the way, because they were in so securely. Is it advisable to rebuild the greenhouse using more mastic, or could we get away without?

Any advice gratefully received.

[rustylady]

Most new greenhouses don't use mastic, just spring clips. As you've found out, if you do use mastic or any sealant it makes it really hard if you have to replace panes. Obviously everyone hopes the panes won't ever get broken, but it can happen - either vandalism, accident or old age. It is much easier to replace panes if they're not permanently fixed in place.

[Mrs Dobby]

If you're worried about sealing it, then get some of the draught excluder type sticky backed foam, we used in on our 2nd hand greenhouse (that had also been mastiked previously), and gives a firm footing for the glass as well as some cushioning, plus makes the w clips have to work a bit harder, so much more secure!

We got ours off ebay, 5 rolls for about £12 if I remember, and used most of it on a 10' by 8'

Hope this is of help!

[Snadger]

Depends whether it's aluminium or wood framed? If aluminuium it should have rubber seals to seat the glass on and shouldn't really need mastic.

A wooden greenhouse frame could rely on mastic or putty though!

I spent last weekend in my homemade wooden greenhouse mastic-ing where the rain was coming in! When I say mastic, I really mean silicone which is water repellant but comes off quite easily if required! As a drip appeared I siliconed the contact area between wood and glass, only to have the water appear further down the slope. Eventually after chasing leaks I got the majority sealed off, doesn't help though when the wooden frame is rotten to start with!

[nick the grief]

If it's aluminium then I would buy some new seals from NA KAys ( they sell two sorts) The last thisg you want to do is mastic it is as it will be ridgid and won't flex in the wind & could smash all your glass. the clips are designed to flex with the frame

[Peter]

Actually mastic is misleading its more like blutack.

I used the mastic bead type stuff to put the glass on top of before using the spring steel tape clips on my secondhand house.

It came from Kays, six beads per drum, rolled up in greaseproof paper.
More like bluetack than mastic, it is essentail to cushion the glass from the metal.

[nick the grief]

Spot on Peter, I think it's grey in colour isn't it?

[Peter]

Spot on Peter, I think it's grey in colour isn't it?

Without a rummage in the garage, Yes.

[muckdiva]

Thanks for the advice everyone, a great help.