Plumber chased out wall for radiator pipes (brick, lime render) - what's the best way filling?

[GeoffSmith]

Hi everyone, 

 

Just had a plumber fit a radiator in our living room, and we had him chase out the wall to fit the pipes. Everything's installed fine, I'm just wondering how I go about filling the hole in the pipes - what's the best practice? The chase is 80mm wide, and 2m long. Can I just fill it with bonding and then Easifill over the top, or do I need to fill with lime render?

 

Ideally, since it's such a small chase, I'm hoping it's just ok to do it the modern way and avoid lime, but I'll do whatever needs to be done. 

 

Also, side question - do I have to protect the copper pipes, or if it OK to just completely surround them in whatever I end up using?

[SteamyTea]

3 hours ago, GeoffSmith said:

do I have to protect the copper pipes

If it is an external wall, then yes, with insulation.

Generally best to insulate pipework anyway.

 

It is also possible that the 'filler' you use could react with the copper.

[saveasteading]

4 hours ago, GeoffSmith said:

to fit the pipes.

Heat in the pipes will be lost into the wall. Can you get some foam rubber or bubblepack or similar behind them?

[Nickfromwales]

https://www.bes.co.uk/class-o-adhesive-tape-black-3mm-x-50mm-x-15m-17548/

 

A bit of this both sides/around, and then nail clip the pipes. Then fill over.

It’s not the best things to chase a wall and bury pipes, but I’ve done it so many times I’ve lost count. 

Heat will leak into the wall, but a comet may also hit planet earth and kill us all, so decide if a neat room is important and accept the compromise afaic  

 

As per @SteamyTea’s comment, under NO CIRCUMSTANCES should you render or fill onto bare copper pipes. In a previous life, if I had to do this, I usually used 10mm plastic coated copper.

[GeoffSmith]

Argh, bugger, I don't think that's going to be possible, there won't be enough room to put a jacket round the pipes and the plumber has filled a bunch of it with expanding foam to hold in place. 

 

It is an external wall, but it's a cavity wall with foam bead insulation

 

 

I'll see if I can get enough space around the pipes to cover with that tape, thanks so much for the advice. As per the material, can I just use normal bonding instead of lime?

 

Edited October 21 by GeoffSmith

[Andehh]

Wrap pipes in duct tape, slight fill of expanding foam behind them?

 

 That's gotta get you half way there?

[Andehh]

Even try Armaflex tape?

[saveasteading]

3 hours ago, GeoffSmith said:

the plumber has filled a bunch of it with expanding foam

AAArrggh. Maybe it will be ok.....but expanding foam is used far too often because it is a quick bodge.

 

Does the can say anything about heat / shrinkage /reactions against copper?

[Nickfromwales]

10 hours ago, Andehh said:

Even try Armaflex tape?

Same kind of stuff I linked above, just a cheaper brand

[Nickfromwales]

12 hours ago, GeoffSmith said:

Argh, bugger, I don't think that's going to be possible, there won't be enough room to put a jacket round the pipes and the plumber has filled a bunch of it with expanding foam to hold in place. 

 

It is an external wall, but it's a cavity wall with foam bead insulation

 

 

I'll see if I can get enough space around the pipes to cover with that tape, thanks so much for the advice. As per the material, can I just use normal bonding instead of lime?

 

Bonding will be fine, just don’t try to fill it all in one set. Half fill, leave 24hrs, then final fill just a bit shy. Then finish with Easi-fill or Tupret filler which will sand back easily.

If you need to remove the plumbers foam then it’ll just scrape out tbh.

[GeoffSmith]

Thanks for the advice guys, I really appreciate it. I've thought about this a lot, and it seems that short of ripping the pipes out, making the chase bigger, and switching to plastic, my best option is as follows:

 

Coat front of pipes in Denso tape, and then backfill the pipes with expanding foam so that they are at least completely sealed. Then cover front with bonding, then skim. 

 

Is that a solution, or is there something better I can do for the same amount of work? I'd love ot insulate these pipes, but unfortunately, they just aren't far enough apart to get the jackets on them

[Alan Ambrose]

I guess it's possible the foam has some insulation value anyway.

[GeoffSmith]

This seems pretty good:

 

https://www.toolstation.com/soudal-genius-gun-pipe-plumbing-foam/p14637

[saveasteading]

Denso is vaseline on a bandage. I expect it will soak into the plaster as an oily stain

 

[GeoffSmith]

So just use duct tape, do you think?

[Andehh]

8 hours ago, GeoffSmith said:

 

Coat front of pipes in Denso tape, and then backfill the pipes with expanding foam so that they are at least completely sealed. Then cover front with bonding, then skim. 

 

Is that a solution, or is there something better I can do for the same amount of work? I'd love ot insulate these pipes, but unfortunately, they just aren't far enough apart to get the jackets on them

 

Just do this!

 

Very much over thinking it, this approach will work perfectly!

[GeoffSmith]

They didn't have Denso tape at hand, so I've used duct tape instead, and then backfilled with that insulated expanding foam I posted above. Can I be sure that the bonding I put over will stick to the duct tape?

 

Also, when I wrapped the pipes, instead of wrapping them individually, I wrapped them as one, because I figured the 15mm gap between them would be good for any expansion, movement over time etc.. Does that sound sensible?

[Nickfromwales]

15 minutes ago, GeoffSmith said:

They didn't have Denso tape at hand, so I've used duct tape instead

Thank feck you didn't use Denso tape!! The grease bleeds into the plasterwork and out to the painted surface, and you'd have had to hack that all off and do it all again in a couple of months, especially when the heat gets to the grease!!!!

Denso is now banned in most instances, bloody ghastly stuff tbf.

[saveasteading]

5 minutes ago, Nickfromwales said:

The grease bleeds into the plasterwork 

I said that earlier, and that I don't generally favour expanding foam.

In some discussions where the advice isn't wanted I duck out.

[GeoffSmith]

Hi mate, it's not that I didn't want the advice, it's that I couldn't see an alternative solution to filling the gap and still allowing for expansion, etc. The advice is always wanted, I generally only have common sense to rely on, which fails regularly, hence why I come here!

 

 

[GeoffSmith]

Hi everyone, just have a couple more questions:

 

So I have my pipes covered as described, with foam behind and duct tape over the front - I'm about to fill the chase. I'm using SBR because the walls are lime and brick, with hardwall plaster. 

 

Can I put the SBR over the duct tape, and can I be sure that the hardwall plater will stick to it?

 

Thanks!

[Nickfromwales]

SBR won’t really adhere to the duct tape, maybe use some 4” scrim (plasterers) tape to give it some help?

[GeoffSmith]

ah cool, thanks Nick, I have some, so just put it directly over the duct tape?

[SteamyTea]

Won't the pipe expand and contract during the heating season, so short of something quite flexible, not much will stay stuck to it.

[joe90]

2 hours ago, SteamyTea said:

Won't the pipe expand and contract during the heating season, so short of something quite flexible, not much will stay stuck to it.

IMO The foam behind will deal with the expansion and the scrim and plaster form a bridge over the pipes, just SBR the walls/plaster to grip both sides. No need for the pipes/duct tape to stick to the new plaster.