Help soundproofing upstairs floor

[traygamchris]

In my house in France the upstairs roof space has been converted into a new room. The trouble is the floor - you can hear anyone even tip-toing on it.

The floor sits on 9 inch x 6 inch oak beams, 5 metres long at 24 inch centres, so I don't have any concerns about them taking the weight. To level the floor wooden planks have been attached to the side of each beam and the floor - 20mm x 50mm thick planks - has been fixed to this. It's not very well done and my plan is to replace everything.

Has anyone got any idea how, when I do, I can reduce the sound coming from the upstairs to downstairs and vice versa? I don't have the luxury of being able to put in a floating floor because of the head height so, somehow, I have to work on top of the old beams. Also, I know carpet would help but it's not very French!

Thanks for you help in advance,
Chris

 

[ajrobb]

I'm no expert, but 600mm floor joist spacing seems a bit too wide.

It sounds like the joists are sagging. How about rubber furring strips and gluing the floorboards together just resting on top?

 

[mointainwalker]

@ajr

I don't think joists of that size will be sagging just because they are at 600 mm or so spacings even with the 5 m span.

As I read it, there are only the floor-boards between the two rooms which will transmit huge amounts of noise.

My suggestion is to insulate below the floor and between the joists using compressed fibre-wool . How much you decide to do will depend how much of the beams you wish toleave exposed below.

1) Decide what material you intend to use between the joists as your new visual "ceiling"

2) Taking into account the thickness of this and how much original joist you wish to leave exposed gives you the available depth to fill with sound-deading.

3) The depth of material required is 2 x available vertical space as compressed fibre will give better results.

4) You may also wish to put a sound-absorbing material on top of the joists to prevent transmission of impact noise from the floor. In French DIY magazines, they always recommend a product called "Phaltex" for this. Have not used it myself, don't know what it costs.

 

[traygamchris]

Hi Mointainwalker,

You hit the nail on the head, so to speak The beams aren't sagging but there are only the floorboards between the two rooms and to all intents and purposes they are fixed directly to the beams.

From everything I've read I think you're right about insulating below the floor and I'll also look out for Phaltex.

Thanks for taking the trouble to reply. Now all I've got to figure out is how to cut plasterboard or another ceiling material to the irregular shape of the beams