Loft insulation - Good or Bad for condensation

[mattysk]

Hi there,

I'm pretty sure I have a handle on the root cause of condensation in the loft (//www.diynot.com/forums/viewtopic.php?t=160032)

But one thing that I seem to get different answers on is loft insulation - I'm talking about fibre glass based normal loft insulation that isn't meant as a vapour barrier and is proplerly installed. Basically the two answers come down to:

1) Insulation makes it worse - Insulation makes the loft space colder so that it can't hold as much water in the air so when this moisture come into contact with the cold roof it forms condensation

2) Insulation makes it better - Because the loft space is cooler, the difference between the roof temp and the air temp is less so when the moisture in the roof space hits the cold roof condensation is less likely to form.

So which is it? Any answers would be welcome!

 

[freddiemercurystwin]

Neither, the greater the loft (ceiling level) insulation the less moisture enters the loft.

Furthermore condensation in a loft is not a problem provided it has adequate ventilation whether you zero insulation or 300mm.

 

[mattysk]

OK thanks!

Iwas sure that it git worse at my house it got worse after the insulation was installed but it might have been something else.