Flat conversion - Suspended ceiling.

[Monsoon]

Hello,

I have a project coming up to convert a workshop/office into two flat (ground and first floor)

I want to create a fully independent suspended ceiling on the ground floor to accommodate the sound and heat insulation. Along with electrical cables and pipework.

Ceiling height = 3m
Length = 7.8m
Width = 6.3m

Open plan i.e. no supporting walls

See drawing of proposed suspended ceiling:-

My plan:-

1) Attach a 6.30m timber I beam with joist hangers across the centre of the room

2) Place timber battens on walls to support new ceiling joists

3) Attach new timber joist(3.90m) to the I beam and the timber battens at 600mm intervals.

4) Cover new ceiling with two layers of plasterboard[/img]

My Question:-

Is this best solution?
What size timber should I use for the ceiling joists? They will be a dead weight, just supporting themselves, rockwool and 2 layers of plasterboard.

 

[jbonding]

talk to BCO im sure your gonna have to if you go ahead with your plans

 

[masona]

Monsoon,
Have you thought about using suspended ceiling with insulated ceiling tiles? A lot cheaper, quicker and easier for service etc. Done a few of these under the garages with room above

 

[Monsoon]

talk to BCO im sure your gonna have to if you go ahead with your plans

It's a material change of use, so the BCO will certainly need to know what I plan to do.

It really can't be that hard to ascertain the size of timber required to hold up the plasterboad?

I seen a number of tables on the web but they all factor in an 'imposed load' i.e. us humans and all the other stuff we put on our floor.

My new suspended ceiling just needs to take a 'dead weight' ie. itself

 

[Monsoon]

Monsoon,
Have you thought about using suspended ceiling with insulated ceiling tiles? A lot cheaper, quicker and easier for service etc. Done a few of these under the garages with room above

I pretty much discarded the tile look as I want to plasterboad - it's going to be residential flat.

 

[Static]

Are you going to allow access to the void for mainentance, also what will the void size be?

 

[Monsoon]

Are you going to allow access to the void for mainentance, also what will the void size be?

The void will be approx 300mm. This will give me plenty of space to buffer the sound and run plasic pipework and wires.

No plans to allow access to the void

 

[Static]

Your looking at 150x50 ceiling joists with something in the region of 406dp TJI joist as main central beam or 2No 306's or maybe a paralam beam. Thats assuming no access to the void.

 

[Monsoon]

Your looking at 150x50 ceiling joists with something in the region of 406dp TJI joist as main central beam or 2No 306's or maybe a paralam beam. Thats assuming no access to the void.

Cheers Static that exactly the kind of info I need.

150X50 would it be just sawn timber? How much do you think the cost of materials will be for the job?

 

[Static]

145x47 C16 timbers should be available at any local timber merchants. No idea on costs.

 

[Roofer]

Why have a new supporting timber structure? You must have the existing ceiling to hang off of so would this be a solution or perhaps this

 

[Monsoon]

145x47 C16 timbers should be available at any local timber merchants. No idea on costs.

Having a look on the Building reg tables it says:- http://66.249.93.104/search?q=cache..._walls.htm+c16+joist&hl=en&gl=uk&ct=clnk&cd=2

47 x 147 mm a span of 2.61m with 600mm spacing

Now that is factoring in an imposed load of upto 1.5 kN/sq.m. and a dead load of upto 0.5 kN/sq.m.

I'm not sure how I would calculate the kN/sq.m. of my suspended ceiling but I would have thought around 0.25 kN/sq.m.

Surely if that is the case I can get away with much smaller timber joists? I do have an extra 1.2m span maybe only 1/10th of the load.

 

[Roofer]

Monsoon, we posted at the same time, did you read my post?

Why have a new supporting timber structure? You must have the existing ceiling to hang off of so would this be a solution or perhaps this

 

[Monsoon]

Why have a new supporting timber structure? You must have the existing ceiling to hang off of so would this be a solution or perhaps this

I have not ruled this out as an option.

Although my mind is not made up, the reason why I was leaning *away* from a metal suspended ceiling is:-

1. I would need access to to the existing floor joists to attach the metal supports. At the moment it is double plaster boarded. Leaving it undisturbed will give me added sound insulation, create less work and mess.

2. I've repeatedly read that the best solution for sound insulation is to create a totally independent ceiling. The metal will create an attachments to the joists above. I'm sure the sound transmission will be small but nevertheless it's not not totally independent.

3. I don't have any experience of working with these metal frames and no idea of cost to cover some 50m2 of ceiling. Wood just seems like a simple structually sounds solution.

 

[Static]

145x47 C16 @ 400c/c with a dead loading of 0.6kN/m2 can span 3.9m, as i said before thats with 0 live load. Your whole idea will be a little springy and your looking at about 6-10mm deflection in places, but thats within acceptable limits (just) and there is no live loading to create cracks.
A less flexible option would be 170x47 members @ 400 centres (also will get passed by building regs easier).