I am currently having my bitumen floor levelled in readiness for my laying an engineered wood floor. I had been looking at the foil backed green type underlay which works out at around £2.60 per sqm. However, the guy doing the levelling lays floors as well (well respected and been in the trade for decades) and has shown me some underlay which he recommends. It is foil backed but a heavier material than what I had been considering. He charges £70 a roll (£4.60 sqm) but says it is worth paying the extra. Should I go with his recommendation or will the cheaper stuff do the job just a well?