Notch big enough for pipe insulation?

[turpis]

Just wanted to check I'm not missing something before I go and swap my copper pipes for plastic.

Say you want to run 15mm copper heating pipes perpendicular to joists and use foam insulation which is typically 13mm. Because it's copper you need to notch the joists rather than hole them. The total pipe + insulation diameter is 45mm. That's beyond the maximum 35mm notch depth.

So instead, you skip insulation on the notched sections so the bottom of the pipe is in contact with the joist and there's a 13mm air gap above it. You still need 13mm above so the pipe sections between joists can be insulated. That takes the notch depth to 28mm which is only permitted for joists >225mm deep.

This means that an installation on typical <200mm joists would need sistering / reinforcement, or use of foil-type insulation, at which point it's easier and cheaper to just use plastic pipe and hole the joist rather than notch it.

So are insulated copper heating installations basically unheard of?

 

[endecotp]

15mm pipes are probably serving a single radiator in the same room, so it can be argued that heat loss from those pipes is not lost because it usefully heats the room.

So are insulated copper heating installations basically unheard of?

There are places to route pipes other than through joists!

But yeah, based on places that I’ve lived and many photos posted here, it’s rare to find insulated pipes. Which is a bit depressing.

 

[turpis]

15mm pipes are probably serving a single radiator in the same room, so it can be argued that heat loss from those pipes is not lost because it usefully heats the room.

Yeah I've heard this line of thinking. I don't agree with it because, in my old house at least, the space between floors is fairly draughty + any heat escaping up will be absorbed by the floorboards / carpet rather than actually heating the room. Building regs for new builds also says any CH pipework in voids should be insulated.

There are places to route pipes other than through joists!

I guess you mean visible pipework / boxing? Yuck!

 

[endecotp]

I guess you mean visible pipework / boxing? Yuck!

I was thinking below the ground floor joists, above the top floor ceiling joists, buried in walls. routed via cupboards, and so on.

 

[StephenStephen]

As an amateur, what I've done when the pipe is running just under the floorboards is:
- I use 25 mm insulation if I can find it, or double up on the thinner stuff and tape the second layer on
- I trim off the top of the insulation so that it forms something like a U shape, and forms a pretty good thermal seal with the underside of the floorboards
- I don't bother insulating in the notch itself, I just make sure that the insulation is firmly butted up either side of the joist

...but to be honest, I'd rather run plastic (unless I'll have no future access) than notch joists.

 

[Madrab]

Certainly the standard would be to insulate CH pipework - more so the 22mm backbone but the 15mm as far as possible. Nothing to say that the pipework can't be fully insulated between the joists and the sections in the notches wrapped in felt

Because it's copper you need to notch the joists rather than hole them

Who said that? Smaller sections of copper could be used and then soldered but notching is more ideal as there's obviously less work.

So are insulated copper heating installations basically unheard of?

Not at all, did a full copper installation last year fully insulated but they did have larger joists and notching wasn't an issue but it is becoming less sought after and I get clients now asking for plastic to be used rather than copper. Time and cost seems to be a deciding factor.

30m of 22mm copper is over £210 at current prices, you'll get at least 50m of plastic for similar money