I have a leak from the hot water pipes under the floor.

[Madrab]

Do they need to be cut down lengthwise to go around the pipe until it hits the joist?

The best way is to feed them onto the length of pipe before laying, that way you don't need to cut them. If the pipe is in and live and the lagging is a retrospective job then yes. They usually come with a pre marked cut line - they just need started with a stanley then run a thumb along the line and they should just split.

Then tape back up along the split with the stickiest tape you can find, personally I use gorilla tape as it seems to last for a long time, other tapes are obviously available.

 

[bluenun20]

Thank-you.

I did not explain myself very well.

I meant as the pipe will be fixed to the joists by nail in pipe clips the pipe will be touching the joists, not allowing the lagging to go right the way around the pipe.

 

[denso13]

Don't cut the insulation, fit something like galv band to clip it all.

All Purpose Fixing Band

Easy to cut and bend. For securing, supporting and strapping of cable, trunking and ducting.This 10 metre length, 12 x 0.7mm, configuration 8 galvanised TAG fixing band is ideal for use on suspended installations and anchoring.• Configuration 8, galvanised TAG fixing band of metal construction•...

www.toolstation.com

 

[bluenun20]

Thank-you.

I do like that galv band, it will be useful to support the pipe in many places in the bathroom and kitchen where I cannot fit a clip to anything.

In the loft I can wrap in around the lagged pipe and fix it to the joist.

On another note, I did find some of what I think are Mouse droppings under the insulation, laying on the plaster board.

I could hear one about 3 years ago and put a bait station up there in a couple of places and have not heard anything since.
I have ordered some more to put down.

 

[Agile]

If it was my property then I would wish to place pipes under the lagging to reduce the chance of freezing up.

 

[bluenun20]

Thanks for the helpful tips.

I have connected the pipes to the Kitchen hot tap and was surprised that I have decent pressure, it feels the same as when the pipe feeding it was underground, so no pump needed.

There is only 120mm between the airing cupboard wall and the cylinder. I would like to add 1 or 2 more fixings but cannot get a drill in there or swing a hammer. Is there any way to do that?