is all roofing membrane created equal!

I was wondering whether anyone can enlighten me, Ive been quoted wildly differing prices for breathable membrane (100%) to go beneath a slate roof and the obvious question came to mind about quality, web uv15 versus icopal monoperm can anyone enlighten me thanks, Frank

Basically it comes down to tear strengh, amount of layers, permeability and what the manufacturer feels they can charge.

Get samples of either and generally you can feel the difference between the cheaper ones and the more expensive. You can expect to be quoted around £100 per roll for the better ones and as low as £40 ish a roll for the cheaper based on a 75m2 roll.

Dependant on the area of roof you are covering (and the competition you are pricing against), is the difference in cost a huge factor over the whole cost of the roof, if not then the better quality underlay will give a better roof in the long term.

We have used the cheaper underlays and our guys do not like them, they seem to tear easier and aren't so managable if the breeze picks up.

thanks will have a look