But smaller electricity bills must, of course, be related to the cost of lining each glass roof and walls with strips of this clear, bubbled, three-ply plastic. For instance, £19.74 is the recommended retail price for a "small bubble" roll measuring 30 metres long by 0.75 metres wide. Prices for the "large bubble" type, which my friend prefers - "Superior insulation," he says - include £l.75 for a 1.5-square-metre rectangle.
You must also budget for securing the sheets to the greenhouse's frame. For example, 25 plastic clips and extenders cost £3.83.
The clips are very easy to fix - just slot them into the frame, then twist - and they keep the insulating material about an inch from the glass. Support pins perform the same function in wooden-framed structures. About two hours was all the time my friend needed to line a greenhouse measuring approximately 3.65 metres long by 2.75 metres wide.
Any strips and scraps should be saved, because bubbled plastic provides good protection if fragile items have to be entrusted to Postman Pat.
Netlon Ltd, Kelly Street, Blackburn, Lancashire BB2 4PJ (01254 262431).Reuse content