Insulated Plasterboard or filled studs

23 Jan 2013
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United Kingdom
I have been trying to research through forums etc for a while and have still yet to come up with a clear 'best' solution. I appreciate some of this has been asked before by I have some specific questions

I want to internally insulate the external walls in my kitchen (each 7m by 3.5m). The walls are currently dot n dabbed with 12.5mm plasterboard (20 years ago) but these appear not to have adhered well as the wall sounds hollow when tapped. The brick walls have many years of old paint on them so I am looking at mechanical fix solutions.

The 3 solutions I am looking at are:

(1) 2x1 batons at 400mm centres with 50mm Insulated plasterboard mechanically fixed


(2) 2x1 batons at 400mm centres with 50mm foil backed insulation mechanically fixed and joints taped with 12.5mm plasterboard mechanically fixed on top


(3) 3x2 batons at 400mm centres - in-filled with 50mm rigid foil backed insulation & VCL & plasterboarded on top

Are people moving away from using insulated plasterboard? Is this due to higher cost, ease of working, joints in insulation?

Is an air gap required between outer wall and insulation to stop condensation or can the insulation butt up against the wall?

With option 2 above should both the insulation and plasterboard be mechanically fixed?

If I create a stud wall (infilled with insulation) will I get thermal bridging through the studs?

Many Thanks,
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What is the make-up of the existing wall i.e. solid 9", cavity etc?

Painted walls are best battened. Use foil backed plasterboards as well as foil sandwich insulation. Tape all joints on the inso and you will have a pretty effective VCL.

No need for any air gaps, in fact the less the better.
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Another question -
On the Quinn-therm site they recommend wall->rigid insulation->baton->plasterboard.

Is it more efficent to have the insulation against the cold wall or the plasterboard?

Any thoughts? I am starting to get the feeling I am over analysing and should just crack on!
I have seen several methods illustrated on drawings with all that you have mentioned above.

One that architects favour is a continuous layer of insulation, i.e. not between studs but across, and that the insulation sits as near to the warm side as possible.

For example, if you had to insulate on the cold side of a wall, say on the outside of a house or a garage wall, then you would fix the insulation tight against the wall then batten then board.

In your case i would fix battens, then a continuous 50mm layer of foil sandwich insulation across the battens with all joints taped then fix foil backed boards through the inso' and into the battens.
9" solid brick you say, in that case I would favor a stand alone 3" x 2" stud wall, studs @600mm centers (1/2" P/board) fixed floor and ceiling, unsupported from the wall, if room dim allows.
Unless the old plasterboard is defuncked I would leave it in place, affix a breather membrane to it, erect stud wall 75mm mineral insulation hung between studs.

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