Plumbing and cables with wood fibre board insulation

[Sikes]

I'm planning to use wood fibre board insulation on internal side of the walls for the kitchen and bathroom that leads off it. Lime plastering over it. I've never used it before. I can see posts and information about cables (ie using oval conduit fixed to the wall). What is the approach for plumbing? I could try and minimse the amount of pipes on the external facing walls but its not possible for all of the pipework.

A possible solution I was considering is to put a stud frame at the bottom of the wall. The skirting would then cover this frame. Hoping the pipes wouldnt get too cold being fixed to the external facing wall. Any issues with this? Is there a better way?

 

[Kearn]

All my services are surface mounted on the whole… good plumber who can do quality copper work and it’s lovely to look at.

 

[Zebra]

Shouldn't be a problem to mount the pipes on the wall then cut a channel out of the back of the insulation for them. The issue, as you noted, was with them freezing, assuming your walls are solid with no cavity. I don't know that the temperature would get that low between the insulation and the wall that this would be a serious worry, but if it's a concern you could wrap the pipes in their own insulated sleeves.

 

[Sikes]

All my services are surface mounted on the whole… good plumber who can do quality copper work and it’s lovely to look at.

Do you mean you've attached pipes directly onto lime plaster and into wood fibre boards?

 

[Sikes]

Shouldn't be a problem to mount the pipes on the wall then cut a channel out of the back of the insulation for them. The issue, as you noted, was with them freezing, assuming your walls are solid with no cavity. I don't know that the temperature would get that low between the insulation and the wall that this would be a serious worry, but if it's a concern you could wrap the pipes in their own insulated sleeves.

Thank you @Zebra Yes it's solid stone & brick. I was happy with fixing them to the wall and insulating over. Then I started to overthink it.

 

[Kearn]

Shouldn't be a problem to mount the pipes on the wall then cut a channel out of the back of the insulation for them. The issue, as you noted, was with them freezing, assuming your walls are solid with no cavity. I don't know that the temperature would get that low between the insulation and the wall that this would be a serious worry, but if it's a concern you could wrap the pipes in their own insulated sleeves.

It really shouldn’t - if that’s the case, the dew point will be breached and there will be tons of interstatial condensation and mould and the whole insulation setup will be a failure.

Frankly, internal insulation at the depth of a woodfibre board isn’t moving the dial against a solid stone wall. It’s largely unnecessary. So popping pipes behind wouldn’t be an issue from a temp perspective. However, I personally really wouldn’t want to have pipes behind all of that in case something went wrong. It’s a big undertaking to source a leak. And a slow one would do its thing for a long time before showing any symptoms.

 

[Kearn]

Do you mean you've attached pipes directly onto lime plaster and into wood fibre boards?

I’ve no need, we’ve used the timber frame as mounting points. But you could go through the fibre boards into the stone/brick to get a fixing. I’d do it before plastering

 

[CliffordPope]

However, I personally really wouldn’t want to have pipes behind all of that in case something went wrong. It’s a big undertaking to source a leak. And a slow one would do its thing for a long time before showing any symptoms.

We are contemplating adding internal insulation and I had already considered this point and agree your advice sounds sensible.
But it massively adds to the complexities of the job. The thought of moving all the existing pipework inwards by 3" or whatever is daunting. This would include wastepipes, foulwater downpipes? What do you do with a boxed-in corner trunking concealing an insulated flue pipe, hot water pipes to the tank in the roof, cold water supply, hot and cold down pipes to taps, and various electric cables.

Do you insulate inside a built-in cupboard in a wall, alter the doors, insulated the doors instead, or ignore it and count the cupboard as a piece of defacto insulation in itself.

How close can an uninsulated section of flue pipe run to an insulated wall, compared with closeness to an uninsulated stone wall?
Can one leave electricity cables currently chased into the walls behind the insulation as well, or does it have to be replaced in a suitable duct through the insulation? Does it need a duct at all?

All this, not to mention the problem of wooden panelling in the window reveals, moving mouldings round windows, inserting extensions into mouldings (because the reveals are angled in the wall), and moving or replacing covings, all puts me off ever starting the job.

 

[Zebra]

Cables will be OK. You are allowed to put them behind, under or next to insulation, as long as it is only touching them on one side and not completely surrounding them.
I imagine the same will be true of the pipes.