What's the most effective soundproofing material for internal walls?

12.5mm thick Gyproc Soundbloc boards fixed with Green Glue. So long as the existing plaster is good & sound,you can fix directly onto this with the boards & the glue. 1 layer of board fixed with the glue will make a significant difference to your soundproofing,even better with 2 layers of boards but please bear in mind that it might not give you 100% soundproofing as sound can travel through floors & ceilings. You will need approx 2 tubes of the glue per 2400mm x 1200mm board. Any good builders merchant will sell Soundbloc. Details of where to buy Green Glue are here: http://www.ebay.co.uk/itm/Green-Glue-Single-Tube-Revolutionary-Sound-Proofing-/120720532503?pt=LH_DefaultDomain_3&hash=item1c1b812417#ht_3116wt_932 Visit: http://www.greengluecompany.com/ for more information on the product and 'how to' video. If you require any further information,just come back on the forum. Carl.

Hi Sara, Please be aware that not all the noise is coming directly through the walls. Noise is also transmitted through the floor and ceiling joists and any connecting walls. I would recommend a free survey by a specialist company. There is nothing wrong with you then using that information to obtain quotes from other builders. Regards Mike

By internal wall im guessing you mean a stud wall. Dense fibre matting, sound breaker bars and sound block plasterboard on both sides. But bear in mind the above answer