Plumbing for radiators and dry lining

The Barrier

I’m just about to start drylining my new build. In some of the rooms the radiators will be on the outside walls. All of the radiators are coming out from the wall and not up from the ground. The builder is going to dry line first and then cut out the pieces of the dry lining so he can hang the radiators from the wall. The first thing that came into my head when I heard this was cold bridging. I’m looking for advice on best practice here.

heinbloed

You are right to worry.
Not only the thermal bridging is an issue but the holes in the vapour barrier as well.
Radiators can be hung onto dryling, ask a real plumber. If necessary a stronger, more loadbearing lining board can be put behind the radiator. But you can place them on footings as well.
All radiators should be put into the coldest place of a room, usually along the outside wall, under the windows.

Joey the lips

i am not out to prove anyone wrong but I am sure i read somewhere that in timber fram housing it is not necessary to put rads under windows as the walls are vapor sealed.

It actually suggests you put the rads as near the door as possible and even behind them. This way your using dead space and make use of the door draft to circulate heat....

Like i say...if i find the article or regs i will post it..

heinbloed

The radiators should always be positioned in the coldest spot of a room.

Here the SEI on the issue:

http://www.seai.ie/Publications/Your_Home_Publications/Radiators_sizing_and_positioning.pdf

They give further reference to:

http://www.gasman.fsbusiness.co.uk/radiators.htm


See also:

http://www.diyfixit.co.uk/central-heating/radiator-positioning.html

Micky Dolenz

My understanding is, under windows for two reasons.

Hot air raises, meets the cold front of the window and natural circulation begins . Also the space under a window is "dead" space so unlikely to have furniture.

Sparkpea

Toggles can be used on drylining to carry most radiators. If it really is a big heavy rad then you can normally measure out where the brackets are going to be and put in bridging supports. I've also seen someone putting pieces of plywood in behind the drylining roughly where the brackets might be so they dont have to be so accurate with their measurements.

knipex

The Barrier wrote: »

I’m just about to start drylining my new build. In some of the rooms the radiators will be on the outside walls. All of the radiators are coming out from the wall and not up from the ground. The builder is going to dry line first and then cut out the pieces of the dry lining so he can hang the radiators from the wall. The first thing that came into my head when I heard this was cold bridging. I’m looking for advice on best practice here.

I did something similar myself when renovating a room in an older timber frame house.

I'm not a builder, far from an expert on insulation and could have gotten it completely wrong but this is what I did.

All the pipes run in the walls. Pipes insulated, 4" rock-wool in the cavity plus a 50mm insulted dry lining board. Put in the T pieces in the central heating loop and ran two straight pipes (about 400mm long) straight out into the room.

I didn't use a separate vapour barrier as I used foiled slabs and was very very careful when putting them up to ensure that all edges were on studs and joints were neat and parallel. I cut two slots in the plasterboard where the rad pipes came out. Once finished I sprayfoamed all the gaps around the floor (including the slots for the rad pipes) and then taped it. (plasters never skim to the floor).


Its a kids room (kids love climbing) so I didn't trust the slab to hold the weight so after my plasterer finished I screwed a piece of 10mm finished marine ply (after running a seal of builders adhesive around the edges) on the wall to take the weight of the rad. I then pained the wall and the ply before putting reflective foil on the wall.

It looks perfect, you can stand of the rad and my seal was not compromised..

The other option was to hang the ply behind the slab either hanging it between the studs or ontop and notching the insulation to allow for it.

I chose the method I did as it was easier, quicker and didnt sacrafice any insulation.