Insulation Question

Optimal thickness of rockwool for separating floors (timber joist cavity)?

I've got 2 questions about Rockwool / Acoustic Mineral Wool (AMW) and soundproofing my flat.

I've got a ground floor Victorian semi-detached maisonette and I'm looking to install some soundproofing above my ceiling boards. The upstairs flat has their floorboards laid directly on the timber joists, so I know that I'm not going to get rid of the sound completely.

I would like to use Rockwool flexi 1200x400 as the joists are roughly 400mm apart, and these slabs would fit into the cavity. I have done the measurements and I know that I need 64 slabs in total for my bedroom and lounge.

1) My first question is about what thickness of slab I should get. I realise that if money were no objection I would go for the 100mm / 140mm slabs; but that is sadly not the case. I want to know if there's a very big difference between the 50mm and 60mm slabs in terms of sound dampening.

2) Does anyone know where I can get these size slabs from at a reasonable (i.e. lowest) price from? I've noticed that the size that I want isn't readily available, but that a lot of suppliers only stock the 600mm wide slabs, which would mean a whole lot of cutting to size and therefore a LOT of waste.

Thanks, in anticipation of many good, helpful answers :)

2 Answers

Best Answer

It's not clear how you intend to fit the insulation - you will need to take up the floorboards to the upstairs flat - nice if they let you !!

You would be better off fitting sound board plasterboard maybe two layers if it's that bad on your ceilings and then getting them plastered.

Only a suggestion !

Answered 23rd May 2012

SBS Ltd

Member since 23 May 2012

I think,maybe you need to check also for building ventilation and structure of the building...for better acoustic insulation..

Answered 27th Jan 2018

ADV Building Services

Member since 23 Jan 2018

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