I wouldn't be too keen on that method tbh, its very easy for 1200g polythene to be damaged when used in instances such as this. There are several proprietary methods on the market atm, however, if you require further info, i'd recommend reading the following
Thanks for the replies. Given that poly is more fragile than proprietary membranes but if treated gently it still does the same job.
All membranes must be pierced to fix them to the backing surface(b).
I would drill and plug with squirt of silicone and proprietary fixing.
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