Soundproofing question

I've just bought a new house with carpeted bedrooms upstairs and a large rumpus room underneath that I'm turning into my bedroom. The layout is perfect for privacy as my son is 17 and being sydney will probably be at home for a long time yet.

He's very allergic to carpet and it reeks of dog wee so I've already booked someone to rip it all up and polish the beautiful floorboards underneath. The problem is even with the carpet that is there the noisy carry is terrible. We can even hear conversations upstairs and downstairs through the floorboards.

So now our dream of privacy is dying a little and I'm keen for ideas how to soundproof.

First option would be to replace old carpet with an acoustic underlay product of some kind, not ideal given allergies and might cause some issues with deposit I've paid.

I started reading into acoustic foam insulation, spray and ones where you pull off wall panels and ceiling and stick in bats. I'm not sure if that is a super expensive idea or worth embracing. You can access the area between my joists and the floorboards above from the side by pulling down some drywall in a an unfinished storage room behind rumpus room. Feasibly something could be slid in or sprayed in from there.

All the doors are hollow with gaps underneath too so that's something I thought I could improve.

Any thoughts on what I should look into and what options are most cost effective?

The best soundproofing option you can get for between the floors sound proofing:

1) Attach you gyprock ceiling using noise proofing clips (such as Whisper Clips) and hat channels such as:

http://www.buyinsulationproductstore.co ... ing-clips/

2) Gyprock on the ceiling should be double 16 mm plaster with Green Glue in between plasters and acoustic sealant in the gaps or alternatively, a thick double OSB underlayment with green glue below your floorboards.

If all done well, you can achieve STC of 60 which is sound studio level of sound insulation.

Sound Batts themselves as well as spray foam won't be providing much of a noise insulation (may you get 5 STC improvement over standard set up at the best).

Green Glue, WhisperClips and Hat Channels can be all purchased from Amazon.

A cheaper and less effective option will be to go for Mass Loaded Vinyl under your carpet underlayment.

I found the following data very helpful to identify your best sound proofing set ups:

http://www.greengluecompany.com/test-data

(there are both floors and wall set ups there)

Hope it helps

WBR,
Alex

Replacing those doors with proper solid-core units that seal well around the edges is an absolute must - our last place had fantastic insulation and soundproofing but was let down by cheap doors. Never again.

Our approach was to utilise 13mm Boral Soundstop acoustic plasterboard for all of our walls and ceilings, with rockwool insulation bats installed in the walls. With a two-story home, insulation over the ground-floor ceiling would help too. If it's installed by the right people (so not Porter Davis) the plaster gets fitted to rubber mounts and the edges sealed properly, and can make a massive difference. If you can handle the cost and hassle of replacing plasterboard, then you'll get a good outcome.

Another common configuration is to have two layers of plasterboard on the walls, overlapping and staggered but that's a lot of hassle. A combination of 16mm and 13mm board is ideal in this case.

Rockwool insulation is a good product, but it's a finishing touch that delivers a small increase in performance. The plasterboard (both the material itself, but more imoprtantly the installation method) makes the bigger difference. I have very little experience with spray-in wall insulation but I wouldn't hold high hopes for it.

Good underlay will definitely help soak up the sound of footsteps overhead.

In a new build, I'd push you towards double-glazed windows as well, as external noise tends to add to the frustration of noisy kids banging away overhead.

Sound proofing is an expensive and tedious process, and one that requires a thorough understanding of the physics involved.