Differences in types of insulation - walls

Coburger

Hi, I'm thinking of getting the walls of my house insulated and was wondering what people believe is the best way to go forward:

- exterior insulation of house
- interior insulation
- fill cavity walls with foam

Which is the best way to reduce heat loss as all the companies I have contacted who do them state that there way is the best?

Coburger

Lumen

Define "best"?

- Cavity fill with beads is cheapest.
- Cavity fill with foam is bravest.
- Interior insulation is best done very carefully to avoid interstitial condensation.
- Exterior insulation gives most effective heat retention, uses thermal mass of walls, and more freedom inside the envelope, but is expensive and is not appropriate for some period buildings (e.g. red brick).

All of them are best done with consideration for air tightness.

Obviously if you have only 50mm of space in your cavity then there are limits to what you can achieve by adding insulation into that space.

Metric Tensor

Lumen has covered most of it but just to add if you have an open cavity it's almost certain to balls up the effectiveness of external insulation unless you do some super careful (and expensive) detailing.

So pencil in the cost of pumping the cavity along with the external insulation.