External wall insulation having already done internal wall insulation

[benjiman]

Hi,

I had internal wall insulation done on all external facing walls about 5 years back, using insulated plasterboard (30mm)

I'm now thinking of having it done externally. 100mm to really get the benefits during the colder months.

Am I likely to get problems with damp/mould internally if I get this done?

 

[oldbutnotdead]

No. You'll be increasing the temperature of the inside walls, you don't get condensation and mould etc on warm surfaces

 

[benjiman]

Great thanks. That makes sense.

 

[Justin Passing]

Insulation on the INside is what gives you problems. If warm air weeps through your insulation, it meets cold brick and you get condensation inside the wall. If you haven't seen any, ok, - probably!
I'd do the calculations before such an expensive move.

 

[jeds]

Unlikely to cause condensation/dampness, but insulation is subject to the law of diminishing returns. With internal insulation plus the masonry, there's a chance the external insulation won't be adding sufficient benefit to offset the cost. Or at least, payback will be so long you'll never see the benefit. As above, get it calculated against cost and see where you are.