Increasing thickness of concrete wall with formwork/new pour

[Deluks]

My garage is made from concrete sectional panels, as I am converting it into a music rehearsal space it would be useful to be able to increase the thickness/mass of the wall for extra soundproofing.
I 've been thinking of attaching rebar mesh to the walls via the bolts on the stanchions, and fixing ply shuttering up against it to then pour in some concrete to about a 2" thickness. Giving me nearly a 4 inch wall.

Never done this before but would like thoughts on this plan from those that know.

My main points of concern are:

Would the new pour stick to the old panels?

Would 2" be enough space for the concrete to work it's way down to the bottom of the shuttering, or would I get air gaps?

Do it all in one go or section at a time? ( I was thinking a couple of sheets of ply to do an 8ft square at a time.

What mix of concrete would I need, and total cost? (prefer to mix myself to save £££'s)

Minimum depth of coverage to the rebar?

How much is rebar mesh anyway?

Thanks in advance for all replies.

Just to confirm, this will be done with the roof off, as it's being replaced anyway. Will have to pass buckets of concrete up and pour in.

ps. Anyone mentioning eggboxes for soundproofing will be asked to get their coat

 

[noseall]

doesnt sound like a good idea to me.

i have seen wall thickening using sprayed concrete, but this is a speciealist job and not for the diy'er.

concrete at 2 inches thick will be to brittle regardless of re-inforcement.

the shuttering job alone would be quite an undertaking.

cohesion between the two surfaces will be a problem as the garage panels just won't be rigid enough.

if you were to do a job like this then self mix would be more cost effective.

 

[JohnD]

I have a feeling that an additional leaf of blocks would be easier and less unconventional. You could incorporate some insulating slabs in the cavity.

 

[Static]

Or build a timber frame internally with insulation between studs, least that can be removed later.

 

[Deluks]

Or build a timber frame internally with insulation between studs, least that can be removed later.

Thats what I'm, intending to do anyway. However for adequate soundproofing of instruments, I require a decent space between outer wall and studwork, with a thicker outer wall I can decrease the airgap needed and have more floorspace in the studio.

Alternatively how thick can a render coat be? that's a possibility too.

Regarding other comments, I don't see how the current panels wouldn't be rigid enough, they are currently 1½" thick, and reinforced with steel.

Also I dpn't see the shuttering as a problem, as I can bolt the bracing onto the concrete floor.

Thanks again for all replies.