Sound proof plasterboard

[Bragadocia]

Are all sound proof plasterboards pretty much alike? If anyone knows what to look for, I would be very grateful for any wisdom shared.

the more mass (weight) you have the better. Also, all joints and gaps must be very thoroughly sealed or noise will get through them.

Instead of an airspace between the skins, pack with dense mineral wool batts (heavier than loft insulation) which will also muffle noise. Detailing round the edges, and any holes for pipes, is important. Cutting big holes for downlighters means big holes for noise to come through.

If you are talking about a ceiling, there is an advantage in having an extra, suspended ceiling below the original one, so you have two ceilings and a gap.

Carpets in the room above, and a dense felt underlay, will also help. Many leases for flats prohibit hard flooring.

There are technical systems for soundproofing, which may involve rubber membranes, and studwork isolated from the noisy wall or ceiling to prevent transmission. That's specialist work.

Good points covered above. You can get covers to go over spotlights which you can then pack insulation around.
We used 15mm rather than 12.5mm boards. Bear in mind that 15mm acoustic boards 8x4 are pretty heavy!

Thank you, this is all very useful. It's for a property we haven't moved into yet, so trying to get as much sorted as possible before we move in. It's for a wall between our house and next door, where my son (4) will sleep. I'm a bit concerned that he and the little girl (11ish) next door on the other side of the wall might disturb each other. It may not even be necessary, although we can hear her telly when we've been there in the evening. I thought that while we are plastering his walls for decorating (after pulling off the rest of the wood chip) we may as well improve the sound insulation.

Also lift the floor below, and go into the loft above. The brickwork of internal walls is usually shoddily built, since it is out of sight and hidden behind plaster. Look for cracks and gaps, and fill them with mortar. Pack that dense mineral wool against the wall between the floor and the ceiling, up to the next joist, at least. Also take off the skirting and look for gaps and cracks. If there are, or were, back-to-back fireplaces, the party wall between them may be very thin. Bricking up the fireplace (leave a ventilation airbrick) will cut sound.

If the joists go into the party wall rather than parallel to it, take up enough floorboards to hoover out the slot that the joist goes into, spray it with water to moisten it, and inject Expanding Foam to fill the gap around the end of the joist. Do them all in one go, because the injector nozzle will block with hardened foam if you put it aside. Get at least a hundred disposable gloves, and overalls or bonfire clothes, before you start using expanding foam.

As it is a party wall, see if you can put a floor-to-ceiling built-in wardrobe, with doors, against it. When it is filled with sound-absorbing clothes, and the doors are shut, it will muffle noise. Try not to screw it to the wall, fix it to the floor and ceiling.

Excellent, this is very useful. The chimney has already been bricked up, with an air brick. I'm not sure we can stretch the budget to built in wardrobes there at this point, but the alcoves will definitely be full of stuff that might help - shelves of books, clothes, and toy storage.

I am optimistic that the joists will be parallel, as although it is a terrace, the house we have bought was built 10-15 years after the one I am trying to protect against (ours is late 1920s). We have yet to venture into the loft, to have a proper look, but our builders were up there today, so I'll ask them tomorrow.

Thank you very much!

Shelves don't work, because they have no doors.