Cavity wall insulation and sound proofing ?

Question:i would like to improve my home and think that cavity wall insulation could be a good technic. Do you know if it can be applied to modern houses even when they have been built after 2003 ? If not have you any idea about an other technic ?

Answers:
I'm not sure I understand what you are thinking, all houses built for many decades have cavity wall insulation. Perhaps you are thinking of foam that is injected into existing walls or sprayed on to new walls before the drywall is applied. Foam is a better insulator than fiberglass in general but one has to be careful about what the foam off gases, it used to produce a lot of formaldehyde but there are better ones now. Foam is also a good sound killer so acoustically it is better than fiberglass. In terms of investment, if your house was built in 2003 it is well insulated and you will not get a return on investment for a long time foaming the walls or even adding blown-in in the ceiling. The difference on sound stopping will hardly be noticeable because sound enters so many other ways than through walls.