Hair Felt Lagging for Screed?

[kev999]

Hi
I need to put some radiator pipes in concrete screed.
I have been told to use Hair felt lagging of the tubular sleeve kind to cover them in.
Is it right that there is a special kind of hair felt lagging that has a plastic sleeve inside which is used especially for concrete screed or is it OK to just use the normal hair felt with no sleeve?
I have tried two local plumbers merchants and they have never heard of a lagging with a lining in.
If anybody knows if I need the lined lagging could they tell me what national shops I can get it because I really need to get it by tommorrow.
Many thanks

 

[namsag]

Felt push on has a plastic inner but this is not sufficent to protect pipe cover it all over in duct tape first then put felt on

 

[kev999]

Thanks for the reply.
Is felt push on the tubular roll kind, Is there only on sort of this kind, so I can;t make a mistake?
I should cover the pipe with duct tape first?
Will the duct tape stay on ok once it heats up?
I ask because I want to run the heating for a couple of weeks before I screed over the pipes case I have any leaks.

 

[Gasguru]

I use hairfelt lagging (allows expansion) and then double wrap with 50mm wide pvc tape for corrosion protection.

You could use DENSO tape but it's a messy job.

 

[kev999]

So should I wrap the pipe first with the plastic duck tape then put it in the hair felt lagging sleeve?
O rput lagging on then wrap the lagging?

 

[Gasguru]

No....put the lagging on...then wrap with pvc to provide protection. Don't wrap tightly....the lagging provides space for expansion. Make sure there is plenty of room for expansion lenghtways on long pipe runs.

Pipework is supposed to be accesible so you may consider purpose designed pipework trays.

 

[EliteHeat]

Or use the PVC encased copper - hugely, hugely expensive.