Fixing radiator to insulated plasterboard wall

Strummer22

I need to install a new radiator on a wall with 62.5 mm insulated plasterboard over cement render skim and thermalite blockwork. The insulated plasterboard is bonded directly to the render with insulated plasterboard fixings too.

The radiator weighs about 32 kg empty. 

What's the best method to attach the radiator? I had thought long fixings into the blockwork would work, but having doubts now due to a) cold bridging and b) too much load on a single point.

These also appear to be an option: https://www.amazon.co.uk/Bullfix-Universal-Pack-Plasterboard-Insulated/dp/B092FSQWS7/ as they claim to hold tens of kg, but I just want to make sure that whatever is used won't damage the insulated plasterboard or risk falling off the wall. Any advice gratefully received.

531063

Ah thermalite block the work of the devil I feel your pain, I would go with some 5mm threaded bar and fix with this https://www.screwfix.com/p/rawlplug-r-kem-ii-styrene-free-polyester-resin-300ml/32863

MikeJXE

!00/120mm x 8mm frame fixers from Wicks 

Murmansk

I'm not intimately familiar with Thermalite blocks but I have used the resin suggested above lots of times on problem walls and it's very good stuff. There are YouTube videos showing how to use it such as this one:

https://youtu.be/Wl0QhjtPtdM?si=oYseU7kU9vaLMCNy

FreeBear

531063 said:

Ah thermalite block the work of the devil I feel your pain, I would go with some 5mm threaded bar and fix with this https://www.screwfix.com/p/rawlplug-r-kem-ii-styrene-free-polyester-resin-300ml/32863

I'd go for M6 stud, and make sure there is at least 50mm going in to the blockwork. yes, there will be some cold bridging, but heat from the radiator will negate that.

Is there an alternative wall that the radiator can be bolted to ?

tacpot12

You can also fit reflective foil behind the radiator to offset the cold bridging.

kimwp

I don't know about thermalite block, but I used corefix screws to fit a radiator to insulated plasterboard on bricks. 4 screws take 100kg.

stuart45

Corefix are used because the screws can pull the plasterboard in and break it on dot and dab.

Strummer22

It's not dot and dab, the board has been bonded using adhesive so it sits flush to the wall. Thanks for the advice, a majority of you advise regular (but long) fixings into the blockwork. Our plumber agrees. 

I'll let you know if this goes wrong for any reason!

FFHillbilly

Strummer22 said:

It's not dot and dab, the board has been bonded using adhesive so it sits flush to the wall. Thanks for the advice, a majority of you advise regular (but long) fixings into the blockwork. Our plumber agrees. 

I'll let you know if this goes wrong for any reason!

sounds a bit like dot and dab to be fair. I think the point Stuart45 was making is you can have the absolute best fix in the world into the block, but it's easy to just crush the plasterboard or insulation which will cause movement and the fixing will no longer be tight. corefix is a prefect solution for this

531063

Strummer22 said:

It's not dot and dab, the board has been bonded using adhesive so it sits flush to the wall. Thanks for the advice, a majority of you advise regular (but long) fixings into the blockwork. Our plumber agrees. 

I'll let you know if this goes wrong for any reason!

Your biggest problem is the block it just crumbles to dust once you drill into it and try to use any sort of expanding fitting