Floor joist question any help would be great

Is it also a floor?

 

Why are you adding this much material to your ceiling?

 

have you checked your sums ? - that's over 300Kg - how much does a sheet PB weigh ? - 20Kg maybe ? - that's a lot of PB for room that's only 3 1/2m wide

it is a bowling alley ?

 

I don't have any span tables to hand and it is an unusual joist size and spacing so can't really say but it also may not be the best solution.

 

where did the need for two layers come from ?

for peace of mind you might want to either get the sound proofing or the capacity of your existing timbers professionally looked at (and calculated)

 

is that what's been calculated for you ?

 

you can't just add another 300Kg + off the bottom of timber structure when the top loading is unknown - you need to get a proper structural assessment done - and while that's being done ask whoever has specified double skins of PB for ceiling sound reduction to look at the alternatives - there are plenty and they weigh a heck of a lot less that the current solution

 

As Sean says 300kg is out of the question if the load above is unknown. I recently soundproofed a conference room using Soundblock, yes it is heavy but there are better alternatives than two layers. Have a look at some of the soundblocking closed cell foams that are available, much lighter and very effective.

 

have you enough height to put a suspended ceiling in,this is a far more effective way of sound proofing,the more you drop it the better,but the minimum is about 7 to 8 inch

 

Help and advice please! I am building a Garage with an Office above. Span of the Garage is 6.2 metres length is 8.0 metres. What size joists should I use to form the upstairs floor?

Thanks

 

If you are building the garage then you should use attic trusses. End of.

 

End of......one attic joist is how many metres from the other end?....and how far is one side from the other?.......and how far from top to bottom? Information rather than just throw away lines will be much appreciated please......end of.....this question!