Cavity Wall Insulation - will it cause dampness or any problems?

Mojisola

fenwick458 wrote: »

so if you want insulation, you would need to stud the walls out and stick some sheets of insulation inside the stud, then plasterboard and skim. unless it's freezing cold and costs a fortune to heat i wouldn't bother

I would say do consider this. We've done it with two rooms that have three outside walls and it has made an enormous difference. Overall the house is keeping much warmer and the comfort in the room is greatly improved.

tony6403

anotherbaldrick wrote: »

In an unfilled uninsulated cavity wall void the air does not remain static, if it did, you would not be thinking of wall insulation as static air is a good insulation material. The air circulates in the void by convection , by picking up heat from the face of the inside wall and rising and loosing heat to the face of the outside wall leaf. Grade 1 Pysics.

How does the moisture escape?

anotherbaldrick

tony6403 wrote: »

How does the moisture escape?

Through the porosity of the external brick leaf. When the weather conditions improve the moisture is wicked to the outside face to evaporate. Remember, if you do not know already all house bricks are water permeable. A good dry windy day will dry out the previously sodden wall.

Leif

I once rented a flat in an old house, which I assume lacked cavity walls. At 7pm the chiropracter who owned the house turned the heating off and went home. It was amazing how quickly the house cooled down and became freezing. How much are you paying each year for central heating? Compare that to a well insulated house, and the cost of adding insulation, and that will tell you how long it will take to pay back. Still, you'll have to redecorate, which I assume would mean replacing skirting board, and coving, and painting walls.

fenwick458

anotherbaldrick wrote: »

Through the porosity of the external brick leaf. When the weather conditions improve the moisture is wicked to the outside face to evaporate. Remember, if you do not know already all house bricks are water permeable. A good dry windy day will dry out the previously sodden wall.

the bricks might be but what about rendering? modern render with rendermix in is pretty waterproof to stop any water getting in.
i would have said moisture is removed by ventilation, air bricks in at damp course level and then an open cavity into the loft space

anotherbaldrick

In ours the wall cavity is sealed off at roof level and their are no vents to the cavity except a couple of open perpends above lintels where thre is a cavity tray. At the foot of the wall the cavity tray tilts to the ouside face so that any moisture droplets will drain through the exterior wall leaf.

David_Aldred

Please see my previous posts on the subjects of both cavity wall insulation and cavity wall ties in relation to dampness which may be helpful regarding your query - Kindest regards, David Aldred Independent damp and timber surveyor

anotherdollar

thanks to all your advice.

macman

My advice is that all this is irrelevant, as a pre-1900 property will not have cavity walls.