Is there a difference between the PVC membrane used for roofing and the PVC membrane used for site-installed liners in swimming pools? At a superficial level both are 60 mil (1.5mm) thick (other thicknesses available), have a polyester (or fiberglass) scrim/mesh sandwiched into it, and are highly UV and chemical resistant. PVC membrane used for roofing though is about 1/4 to 1/2 the cost of pool membrane. Other than color/print selection (greater for pools) is there a reason for this?
I'm curious to know because I live in Nicaragua and am building a pool and feel that a site-installed liner is the best option for waterproofing it. However, neither of these materials are available domestically and the shipping, brokerage, import duties and taxes can be very high. "Can be high" because the duties on "pool" materials are 50% whereas on "construction" materials only 5%. Also, an architect friend of mine knows of a project using PVC membrane for roofing that has an overage of material that he can pick up for a fraction of what it would cost me to import new material.
Tile and pre-made liners have higher risks and costs (higher purchase cost, higher shipping costs and duties, worthless warranties, high replacement costs) which is why a site-installed liner seems best. I've tried to talk to a few manufacturers and vendors about the difference but they won't say anything unless I can prove that I at least have a legitimate order for their product (and I really don't want to go through the deception and time of faking an order). So I was hoping some of you may have some thoughts on this. Thanks for dropping by the post.