Attaching Radiator to Timber Frame Wall

[efunc]

Hello,

I need some advice regarding the fitting of an electric radiator to the wall of my garden room. Unfortunately I didn't anticipate doing this whilst in the design stage and now it's too late to put in adequate support structures. The radiator is 160cm tall by 23.6cm wide:

Here is the room as it is now, and I'd like the radiator on this side wall positioned about 40cm to the right of that side window:

Here is the underlying wall construction:

The radiator is 12kg in weight which seems like a lot to have hanging from just plasterboard. I've obviously got the benefit of a vertical timber on either the right or the left of the radiator, but since these are 40cm apart and the radiator is 23.6cm wide, I won't be able to rely on both. Likewise the noggin in the center isn't any use either. I guess the positioning on the brackets are determined by the radiator design, and can't be placed arbitrarily:

Do I have any other options to fit this, or do I have to go with a standard convection or fan heater instead?

Thanks for any advice.

 

[ReJect]

The first vertical stud (about 400mm to the right of the window would give good fixing point there on top and bottom left side brackets. The right side you could use heavy duty cavity fixings.
Not as good as having timber on both sides to fix to, but still strong.

 

[^woody^]

Gripit fixings

 

[efunc]

Thank you both. Yes, having at least one vertical stud to use makes it less of a risk, and actually, being so narrow means that I'm not loading the unsupported side as much as I would be if it was a very wide radiator I guess. The challenge of course is finding and hitting the stud square on, since it's only a 4cm target.

Is there a problem using the Gripit fixings on plasterboard fitted flush to PIR insulation? I know you can get a tool to cut behind the plasterboard, I'm just wondering how much clearance is needed and if the wings can force their way open even without clearing it. I think I may have a 5-10mm void behind the plasterboard at this area so it may just work anyway.

 

[ReJect]

Stud detectors can work well, but you could use metal detector or strong magnet to find screw centres.
Or just use sharp nail or drill with fine drill bit to find timber.
Any holes easily filled later.

 

[23vc]

12kg without water in presumably?
Those spring toggles can take a decent load, done a few towel radiators using them and rock solid. Not sure if that’s the same thing as a gripit

argh just seen you said it’s got PIR directly behind the board, so they wont work.
Can’t you just drill some really small holes to find the stud which you can then fill in?

edit: sorry just basically repeated the above post from reject

 

[efunc]

12kg without water in presumably?

Well you ask a really crucial question. Here's the product page: Milano Aruba

I've called the supplier a couple of times to check and they said it's 12Kg, but didn't sound that sure and presumably were just reading the same info off their website. I think these are basically the same as their plumbed-in version which is 11Kg and found here.

The electric one comes pre-filled with fluid, but I'm having a hard time believing that only weighs an extra 1kg!

 

[23vc]

If it’s small/posh style, it may not contain much more than a kilo of water. When you drain them out you don’t get that much. I think due to your insulation you’re going to have to find a stud anyway.

 

[bsr]

I have a towel rail on four brown Grip It fixings, in insulated PB, using the undercutting tool. It has coped with my kids trying to climb it.

 

[efunc]

I have a towel rail on four brown Grip It fixings, in insulated PB, using the undercutting tool. It has coped with my kids trying to climb it.

Thanks bsr. Did you use the 18mm red ones? I'd like to use the smallest ones I can get away with because they make quite a hole in your plasterboard, but red or yellow seem recommended for radiators. Incidentally, if the the advertised loads seem a little on the optimistic side it's because they're calculated based on 15mm boards. I'd like to see what they are for 12.5mm boards. I wouldn't be surprised if it was almost half of what they advertise.

 

[bsr]

Brown, as I said above!

 

[efunc]

Brown, as I said above!

Doh!

 

[^woody^]

The room's looking good btw.

 

[efunc]

Thank you! It's getting there. Now clad in cedar but lot's more to complete:

We started cutting through the plasterboard today to start fitting out the sockets, switches and lights though and I think I've made a pretty worrying rookie error. I originally fitted it internally with PIR board, taped it all up and sealed off with VCL too. Then my sparky turned up and said he needed to cut huge chunks of it out to be able to fit the recessed lights and backboxes in later. In order to prevent breaching my VCL I fabricated plastic boxes to sink into the large holes in the insulation and for the downlights I found some 2 litre food tubs to cut down. The idea was to prevent the warm interior air from getting into the cavity space and form condensation:

The problem is, when we finally made the cut-outs today in the plasterboard to reveal the sealed recesses I made, it was all dripping wet inside:

I'm worried I may have caused more of a problem than I solved by sealing everything off the way I have. If warm air collects in these sealed spaces behind electrical fittings it'll condense and eventually corrode and trip out circuits. I'm already seeing slight patches of mould on the walls. Being positive I'm guessing that most of the water I'm seeing is what was released from the wet plaster as it dried and was trapped on the inside of the VCL behind the plasterboard. I'll air the room out for a few days now that I've cut all the holes out for the lights and sockets. But also I have to have a plan for what to do if the problem continues after the build is finished.

 

[John D v2.0]

The problem is there's no insulation behind the backbox so the back of it is freezing cold and a massive thermal bridge.
There will be a minimum amount of insulation needed to prevent it getting too cold.
It is better to trap the condensation in the box then let it form further into the structure though.
If the room has just been plastered them there would be a lot more humidity, so it would be less bad if it's kept dry and well ventilated in future.