Beginner's greenhouse?

To improve the performance you can add a second skin and inflate the space between sheets with a small blower. Its common in the states, they invented it at least 50 years ago

 

It also reduced the "rot" of the polythene that would otherwise be caused where it contacts the (hot) tubular pipework, so although you have to buy 2 x the Polythene it should last longer.

 

The inner skin should last longer as the outer skin takes the brunt of the uv and the weather.
The inflation pressure although minimal will keep the poly tensioned.
Less condensation and it acts a bit like a car airbag in gusty conditions too

I wasn`t surprised when i asked a tunnel manufacturer if they`d ever considered producing double skin tunnels and they replied it wouldn`t be cost effect and recommended bubblewrapping the entire tunnel instead.

 

Kirsten said,

They have a insulation tape that is attached to the metal tubes to insulate them against the polythene cover,you can get different covers some more u/v stabilised and tear proof than others you can get up to 10 years out of them, lot more costly though.
Hex said,

Wondered this myself they should at least give you the option,bubble wrapping the inside is a good idea but attatching it is a nightmare.

 

" Its common in the states, they invented it at least 50 years ago"

I installed about 1/2 acre of double skin, in the mid '70s. A firm from somewhere in the fens, can't remember their name offhand, and maybe they don't exist any more.

 

I haven`t come across any firms in the uk but perhaps the more specialised commercial suppliers offer the option. The usual mainstream ones, mentioning no names certainly don`t.

From a cost cutting point of view, they could easily use a 4mil (100um) inner and a standard thickness outer. The standard fixings will hold double poly as easily as single.
I wonder what the cost difference would be for 5yr uv stabilised bubblewrap plus the fixings versus an extra poly cover plus small blower.

 

The (commercial) house I was involved with (way back then) was heated, so the reason for he double skin was mostly to do with that. But we did build part of the site in single to have a comparison of heating requirements and cropping yield - less light through the double skin of course. But I have no recollection of what the result was :( sorry!

 

Just knowing it exists as an diy option may be useful for those that are considering replacing the tunnel poly
The light reduction could be an issue, although i guess it depends what your trying to grow.
having said that, it should allow more light through than a bubblewrap/glass or bw/poly combination.
I did some tests using 2 layers of 5mil poly and its does seem reasonably transparent even after a shower of rain.

 

"The light reduction could be an issue, although i guess it depends what your trying to grow."

Indeed, I doubt it would matter very much for the amateur. We were growing out-of-season tomatoes ...

 

I have put this question in the wants list but perhaps someone knows where I can get a replacement cover or a roll of this green reinforced plastic, Mine is just starting to show some wear my cold walk in greenhouse is approx 68in x 30 x 78

 

Hi Nathan
Have you tried http://www.allplaz.com/index.html
They do a fair assortment of poly and stuff.

 

Many thanks Hex