I am building a greenhouse and was wondering can I use standard 'household' polythene (which is far less expensive) instead of garden polythene? Is there a significant difference between the polythenes?

not sure of the question but if this helps you can put string to hold your trousers up it does the job ,but its how you want things to look ha ha ha

Nice one Juliano. Ha ha ha

We are going to try this 4mx6m heavy clear tarpaulin sheet down on our allotments it's mere pennies compared to brought normal garden polythene and will do the job just as good.

Just copy and paste the below link.Hel.xxx

http://cgi.ebay.co.uk/ws/eBayISAPI.dll?ViewItem&rd=1&item=290279906628&ssPageName=STRK:MEWA:IT&ih=019

Thankyou Helofadigger, Having looked at the link you gave me, even this seemed a little more expensive than standard thick polyythene. Have you tried this tarpaulin before? I am curious as to whether it works as well as garden grade polythene. Do you know what the difference between garden and standard polythene is, as I cannot seem to find any comparisons of the two anywhere and would ideally like to see the pros and cons of the two when used for a green house.

I think im right in saying this Ellem, hopefully someone else can confirm , but ordinary polythene gets effected by the sun and goes brittle after a while and in turn falls apart where as garden polythene is not effected by sunlight , unfortunately I dont know how long ordinary polythene or the thick stuff lasts out in the sun to work out if its economically viable

Ultra violet rays from the sun deterioates plastic over a period of time depending on the chemical content of said plastic. Usually its the particle size and grade of zinc oxide that stops polythene degrading. Ordinary polythene starts becoming brittle in 12-18 months and is not as good at letting sunlight through compared to greenhouse grade polythene. I'm not sure what you mean by garden polythene.
Greenhouse grade polythene should last for several years because it contains a better (more UV light reflecting chems.) grade of zinc oxide, hence the greater cost.
There's more to it than this, however my knowledge after this becomes sketchy at best.
I hope this helps. If it doesn't, it gave you something to read ;-)