Insulated board on cavity wall

[Super_Paulie]

hi guys.
Any benefit of using an insulated board internally on my insulated cavity wall, mainly on the wall with a radiator? (brick-cavity-block) it would be a dot and dabbed (or foamed) insulated board. I was hoping to reduce the amount of heat lost through the wall behind the radiator but don't know if that is worth my while. I am due to mount the radiator asap and if its worth me doing the insulated board then i'll stand the rad off by the 40mm or whatever when im positioning my tails. So to speak...

 

Cheers guys.

[Mr Punter]

Yes it will help keep the heat in.

[MikeGrahamT21]

It’ll help the heating respond quicker, but it won’t help the room hold it’s heat for as long once the radiator is no longer emitting heat.

[Mr Punter]

15 hours ago, MikeGrahamT21 said:

It’ll help the heating respond quicker, but it won’t help the room hold it’s heat for as long once the radiator is no longer emitting heat.

 

I am not quite with you.  Surely it will reduce the heat losses through the wall by improving the U value and therefore the room will stay warm for longer?

[MikeGrahamT21]

1 hour ago, Mr Punter said:

 

I am not quite with you.  Surely it will reduce the heat losses through the wall by improving the U value and therefore the room will stay warm for longer?

I’d agree with that if it was a solid walled property, but cavity which is filled should in theory hold its heat reasonably well, which is why like I’ve done, external wall insulation is a good addition to cavity, allowing the block work to even out the temperature. Aside from calculations though I don’t know of a property with IWI to compare with.

 

At the same time I’m not in total disagreement with you, internal wall insulation will give a good reduction in u value but you’ll be left with a lot less specific heat capacity in the build up, meaning it’ll take less energy to heat the room to a specific temperature, but will need top up heat more frequently. I’ve a feeling that the heat will soak into another surface or pass through another element which is colder/higher u value, and IWI can create problems with cold bridging which could make even more problems.

 

I never asked, what kind of radiator is it you are putting in (does it have fins on the back or not?), and have you tried any of the radiator panels/foil to reflect the heat into the room and away from the wall? An option like this should give a good outcome with no risk. What was the reason for replacing the radiator? Another question would be are you sure the cavity is properly filled with no gaps? Having recently taken bits of my roof off I found numerous empty pockets and ended up using a long length of timber to push it further down and fill the gaps before topping it up

[Super_Paulie]

4 minutes ago, MikeGrahamT21 said:

I’d agree with that if it was a solid walled property, but cavity which is filled should in theory hold its heat reasonably well, which is why like I’ve done, external wall insulation is a good addition to cavity, allowing the block work to even out the temperature. Aside from calculations though I don’t know of a property with IWI to compare with.

 

At the same time I’m not in total disagreement with you, internal wall insulation will give a good reduction in u value but you’ll be left with a lot less specific heat capacity in the build up, meaning it’ll take less energy to heat the room to a specific temperature, but will need top up heat more frequently. I’ve a feeling that the heat will soak into another surface or pass through another element which is colder/higher u value, and IWI can create problems with cold bridging which could make even more problems.

 

I never asked, what kind of radiator is it you are putting in (does it have fins on the back or not?), and have you tried any of the radiator panels/foil to reflect the heat into the room and away from the wall? An option like this should give a good outcome with no risk. What was the reason for replacing the radiator? Another question would be are you sure the cavity is properly filled with no gaps? Having recently taken bits of my roof off I found numerous empty pockets and ended up using a long length of timber to push it further down and fill the gaps before topping it up

 

its a 2m horizontal cast iron "style" rad in raw metal with triple columns, much like in the attached image. The part of the house its going in is the extension which is still at bare block and is insulated correctly to the best of my knowledge. At this stage im looking to keep the place as insulated as possible and i want to bring the rad circuit online now its getting colder and then i can work on my UFH over the winter, thats all ready to go bar laying the pipes. The rads are more to be eye candy as the UFH will do the bulk of the work.

It seemed a no-brainer to use insulated board behind the rad as id only lose 40mm and the added bonus that it would push out the rad so the tails do not foul on the joist that is close to the wall. The wall is external and north facing, its always baltic in that part of the house even in summer.

 

[MikeGrahamT21]

43 minutes ago, Super_Paulie said:

 

its a 2m horizontal cast iron "style" rad in raw metal with triple columns, much like in the attached image. The part of the house its going in is the extension which is still at bare block and is insulated correctly to the best of my knowledge. At this stage im looking to keep the place as insulated as possible and i want to bring the rad circuit online now its getting colder and then i can work on my UFH over the winter, thats all ready to go bar laying the pipes. The rads are more to be eye candy as the UFH will do the bulk of the work.

It seemed a no-brainer to use insulated board behind the rad as id only lose 40mm and the added bonus that it would push out the rad so the tails do not foul on the joist that is close to the wall. The wall is external and north facing, its always baltic in that part of the house even in summer.

 

is this an extension you have built on with building regulations? If so depending on the width of the cavity you will require some internal wall insulation in order to get it passed as 100mm of any type of insulation in a cavity won’t cut it these days. Make sure all of the external walls if there are more than one are all done the same, which again you’d have to do for BR.

 

 

[Super_Paulie]

6 minutes ago, MikeGrahamT21 said:

is this an extension you have built on with building regulations? If so depending on the width of the cavity you will require some internal wall insulation in order to get it passed as 100mm of any type of insulation in a cavity won’t cut it these days. Make sure all of the external walls if there are more than one are all done the same, which again you’d have to do for BR.

 

 

its all done and passed bar final sign off on fittings. BC didnt require insulated plasterboard nor did my architect specify it, its just my own preference really.

Plans are pre-jun22

Edited October 19, 2023 by Super_Paulie

[MikeGrahamT21]

54 minutes ago, Super_Paulie said:

its all done and passed bar final sign off on fittings. BC didnt require insulated plasterboard nor did my architect specify it, its just my own preference really.

Plans are pre-jun22

Yeah that’ll be why, wouldn’t need it til post june22.