Insulated plasterboard on an internal wall suffering from condensation

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Hi all.

I've read conflicting things about how to do what I'd like to accomplish so thought I'd post my own question as everyone's circumstances are different so here goes.

I live in an end-of-terrace circa 1906 property with cavity walls. Both internal and external walls are of red brick construction, with the inner being plastered.

However, the back of the house gets minimal sunlight and gets cold, especially in the winter. My little girls bedroom is the coldest and her two exterior walls gets condensation building up which can turn to mould if I don't keep on top of things, which adds to the cold. I would like to make her bedroom warmer so I'm going to install insulated plasterboard just on those exterior walls and have them rendered, to at least stop the wall from getting so cold and condensation occurring.

My question is, can I use dot and dab to stick the plasterboard on to the wall (an article I read said insulated PB has vapour protection qualities and so can be used directly even if condensation is prevalent) or should I use battens and fix the PB on to this thus keeping it away from the wall? My only problem here is that I don't have a lot of leeway where depth is concerned, because of the bedroom door frame .

Any advice would be greatly received!

Thanks in advance.
 
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You can use plasterboard foam and a few frame fixers (or screws with plugs). Battens aren't needed. As long as you seal all gaps with foam. Ideally you want to take the plaster back to the brick to maximise space. Don't bother with anything less than 40-50mm insulation unless the room is tiny.
 
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Even though the wall suffers from condensation? Will it not come through the plasterboard over time? Or are you saying that because it is insulated the wall won’t get warm and so the condensation won’t built up? Thanks @motorbiking.
 
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The condensation forms on the inner face of the plasterboard, not behind it. The insulation will hopefully reduce the thermal difference but I suspect that you need to additionally introduce airflow, eg, an air brick.
 
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Even though the wall suffers from condensation? Will it not come through the plasterboard over time? Or are you saying that because it is insulated the wall won’t get warm and so the condensation won’t built up? Thanks @motorbiking.
The condensation is caused by warm, heated air, coming in to contact with the cold surface of the poorly insulated wall. It then condenses and causes damp. If you improve the insulation, less cold will come through the wall and therefore there is no cold surface for the warm air to condense on. Its important that the wall is sealed completely as any warm air that can get through the insulation will condense on the inside of the wall. You really don't want that.

Hence all the gaps have to be filled with foam and any joints properly taped and skimmed.
 
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The condensation is caused by warm, heated air, coming in to contact with the cold surface of the poorly insulated wall. It then condenses and causes damp. If you improve the insulation, less cold will come through the wall and therefore there is no cold surface for the warm air to condense on. Its important that the wall is sealed completely as any warm air that can get through the insulation will condense on the inside of the wall. You really don't want that.

Hence all the gaps have to be filled with foam and any joints properly taped and skimmed.
Terrible post to read after having this recently done and knowing it wasn’t done to this standard. Can’t understand why this isn’t common knowledge/practice for all plasterers
 

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