Plywood Questions

[Reynardine]

With my floor joists exposed I've realised that I can't just lay fermacell flooring straight down onto the joists. A 'sub floor' is required first.

From reading the wiki and other peoples posts here it is clear that MDF or chipboard won't do. My alternatives seem to be replacement floorboards or plywood. I don't like floorboards so my plywood questions are ...

Do my joist centres decide the plywood thickness I must use ?
Must the plywood thickness be 18mm or do regs allow me to go thinner?
What is marine plywood ? Is this what I should buy ?
Is there something obvious I've overlooked ?

Thank you.

 

[mattysupra]

basically 18mm in minimum thickness you should use. As for the marine bit just ask for exterior grade. Its just more stable and resist moister abuse (humidity changes, water spillage etc)

 

[gcol]

What is it you are trying to achieve by using fermacell boards? What flooring are you laying on top?

 

[Reynardine]

What is it you are trying to achieve by using fermacell boards? What flooring are you laying on top?

I'm trying to achieve acoustic insulation. Quite a large area is involved at roughly 30 square metres, covering the bedroom and lounge.

My neighbour below has loud musical tastes. The bass is the problem. At its worst it feels like 100 decibels but I am going to buy a sound meter to verify the actual disturbance level.

My intention is to fill the space between the joists with 100mm high density acoustic mats - like rockwool but more dense. On top of the joists I will fix the 18mm plywood sub floor. Above the sub floor I will lay two floating fermacell floors ( 2x 15mm ) On top of the fermacell floors I will lay some acoustic carpet underlay. Finally, I will put down some new carpet. Fermacell claim a 60 decibel noise reduction using this technique.

 

[freddiemercurystwin]

My neighbour below has loud musical tastes. The bass is the problem

Probably best just to move realistically.

 

[big-all]

the trouble is the bass travels through the structure ceiling joists floor and walls

so although you will reduce it you will have a job to stop it

 

[Jasonb]

I would suggest you get flooring ply this comes 18 or 22mm thick and is T&G jointed on all four sides just like the sheets of flooring chipboard, it also comes in the same 600x2440 which makes it easier to get upstairs or into a lift. The T&G joints will also eliminate air gaps that the sound can travel through.

You will have to go to a decent panel supplier as its not something the DIY sheds will have.

Jason

 

[gcol]

And introduce your neighbour's shins to a claw hammer.

 

[joe-90]

As big-all says, the vibrations travel through the structure of the building and once they are in there - you can't get them out. It's the same principle of how an acoustic guitar works.
Better spending money on legal action against your neighbour. Talk to the Environmental Health people of your local council. You don't have to put up with inconsiderate neighbours.

 

[Reynardine]

Thanks all for your guidance. The interlocking ply sounds promising. I'm not aiming to eliminate the bass noise. If I can minimise it that may be sufficient.

In fact I moved out of the noisy flat in 2000 and have been letting it ever since. The noise reduction I have in mind is for my tenants benefit not mine. I am affected because my last tenants moved out due to the noise from below. The flat is currently empty and I am out of pocket.

I think I'll choose a drummer or trumpet player for my next tenant ... reaches for NME/Melody Maker !

cheers.

 

[JohnD]

your friendly local hitman should be able to cure the noise problem for you.