Building ceiling between exposed beams - best methods

[Melter]

We had our hideous ceiling removed a while ago and now we have a bit of spare cash I want to improve this area. See pic below.

I'm going to plasterboard between the joists and then paint the exposed part of the beams. I also want to add insulation and some soundproofing into this project as we have bedrooms above with 2 noisy kids. I just need an idea of the best way to do this and suggestions of materials to use.

A few questions to start with:
1. Best way to fix the plasterboard. Do I batten along the sides of the beams or perpendicular to the beams on the floorboards?

2. Because I want to insulate and add some soundproofing should I get a board with the soundproofing included and then fill the void with insulation or is there a board that covers both things?

3. If I'm adding the insulation do I need to leave an air gap or can the void be filled?

4. Should I have the boards rendered or is it fine to just paint them?

5. Need some recommendations for materials to use please.

Thanks

 

[cmother1]

Any particular reason for leaving the joists exposed? It would be much easier to board over them. Polyurethane foam boards will give you good (if pricey) thermal insulation, but limited sound-proofing. For this you need something with a high density & consequently weight (eg concrete). Just plasterboard and foam, however, will be a big improvement on bare boards. You couldn't make it noisier than it is now!

 

[Melter]

Any particular reason for leaving the joists exposed?

They have some age to them and are more in keeping with how the cottages once were. Plus when they were covered over completely the room felt smaller.

The house next door has done some lovely work on their beams but left them completely exposed as they still have the original wide floorboards. Our house lost the original floorboards some time in the 70s so a happy medium seems to be to re-board between them.

 

[Deluks]

Sound will be an issue if you don't get the details right.
Whatever you do you will still get a degree of impact noise transmitting through the joists. But even this will be reduced if you proceed as below.

The first weak spot is the existing floorboards. They will be too thin and likely have gaps that will leak sound through.
First job then is to board these over from the underside; to seal the gaps and increase their mass somewhat. You could use plasterboard for this, or chipboard or mdf. I would go with 18mm mdf. Fix with a decent amount of screws ~don't screw right up through the floorboards~

Cut them ever-so-slightly smaller than the area they have to fit into and fill the perimeter with acoustic sealant.

Next you will need to deaden the void. Use rockwool type insulation as this is the best product for this task, bar none. Completely fill the void and slightly compress it ~slightly~

Lastly you will need a ceiling for the room below which also needs to be resistant to sound. More plasterboard, cut to size and fixed to 'side mounted' batten.
If you can get 15mm or 19mm plasterboard for this then even better.

You could leave it painted but giving it a skim will save you a decibel or so of sound as it will increase the mass and fill gaps around the PB.

A few tubes of acoustic sealant will come in handy to fill any gaps and zig-zag some on the uppermost side of the sheets when you do the 'floorboard underboarding'

Use deccy's caulk on the ceiling/joist joins if you decide to paint.

 

[cmother1]

Melter - see Deluks's post above. This is a classy solution - as good as you can aspire to in your situation I reckon.

 

[dasf173]

Thanks for the description - trying to do exactly the same in Edenbridge, Kent.