mxslick. Yes, the polythene sheet is the outer vapor barrier. Barriers, (there's another between the sheetrock and the insulation), are essential when insulating dense structures, like stone/brick, especially in a damp climate. A dew-point will appear somewhere between the inner surface and outside, and the amount of air and water vapour that passes through sheetrock is quite amazing. On the molecular level, it's full of bloody great holes! This dew-water soaks into the insulation, degrades its performance and moves the dew-point toward the sheetrock, and so on. Eventual result- damp patches, fungi, black spots, smells, bigger heating bills etc. I once saw a layer of ghastly pink jelly ( fungus) nearly 2 inches thick on the inside of a non-barriered sheetrock panel- it had collapsed under the weight!
Trumpy, Bent it all myself using a hand pipe-bender. You can't bend straight French 22mm, as it's fully hard and snaps!, so I imported some Brit 22mm for the bends, using 22mm Froggypipe for the straights- see the different color? 22mm is the only French pipe compatible with UK plumbing fittings- they use every diameter from 6mm up, in 2mm steps ( 6-8-10-12-14-16-18-20-22 etc), handy, and as each pipe fits in the next, no need to buy reducers. French plumbers do not solder, they use copper-silver brazing with oxy-propane. They don't buy elbows or tees either, but make these up on site from pipe, using coils of very soft copper tube where manipulations are required.
My fittings are plumbers' lead/tin soldered, or compression with olives. I use an American flux, as it's just unbeatable for top notch joints. For drinking water I use a tin/copper/Al eutectic solder, safer, but more difficult to sweat.
Alan
