How to lag an external pipe?
I have a pipe that carries washing machine waste briefly outside the house (1.5m) before going back inside again.
Fcuk knows why it's plumbed like this - it would have fitted, with some work, behind the kitchen cabinets.
Anyway, it's frozen solid on account of not having enough of an angle on it to drain quickly.
Hence, I can't use the washing machine.
I took it off, thawed it, refitted it, lagged it with the standard foam stuff from B&Q etc, then further insulated it by using some water tank jackets which were redundant after changing the heating to a combi boiler.
It's now frozen solid again.
I'm thinking I need to either put a large circumference sleeve pipe (full bore drain pipe) around it and pack it with fibreglass, or box it in to the wall using whatever waterproof materials come to hand, and then insulate with fibreglass.
How do builders/plumbers usually deal with this?