how do you work out how much pipe is needed?

[beesley121]

im doing a job for a mate. Need to rip out all the non barrier pipe in his house and replace with barrier pipe and new boiler. This is the biggest job ive had since I started up on my own and its going to be the hardest as all the pipes have got to go back in his walls
say this, its also going to be a job that Im not going to be earning the money i want to earn as hes a mate so when costing up materials apart from the obvious ie boiler, rads, trv's etc how do you guys work out how much pipe you will need?
this job will all be done in plastic barrier pipe but I cant help woundering if it will cost less to do it in copper as the pushfit fittings cost a fair bit but plastic is faster to fit. Anyone advise here? its for astandard 3 bedroom detatched house. new build
also, to save money, would you guys re-use the plastic fittings already installed or would you buy new for reassurance. polyplumb fitting used

 

[galaxy_plumbing]

hope that plastic is not for gas supply :bucktooth:

 

[Simon F]

just buy a 50 or 100m roll, its cheaper that way
the same for fittings buy bags of 10,
if you don't use them all they will come in

 

[beesley121]

hope that plastic is not for gas supply :bucktooth:

Don't be daft mate, doin it properly

All to be done using 21.5mm solvent weld with loads of glue just to be sure it's super gas tight. No u gauge needed!!!

 

[Nostrum]

You could use existing fittings but i'd avoid as 1 leak due to a torn O ring will cost you more agro in the long run. Plus if I remember you said it was sludging up so you'd be introducing dirt into a new system unless you wash them all out = hasslehoff

As said buy big rolls of pipe, to be honest the cost of the pipe is negligible for plastic so if you need another roll it may only be an extra £50. The other option if your mate is tight, rip it all out then measure how much you need!

 

[kirkgas]

surely the simplest/only way to measure pipe needed is to work out your runs along floors and up walls for each rad and end up with a total, if using coils of pipe you save on fittings, if using 3m lengths allow st couplings where required, do not on any account reuse any old stuff, you will be trying to do him a favour by saving him a few quid if that, but remember who he will phone/blame in a few months when one of them leaks in the wall