Unusual Wall Construction in 1980's Wimpey Home General problems, solutions, information and advice on fixing to walls of all kinds

[irongeezer]

I am installing some kitchen units for my sister. She lives in a small 1980's Wimpey house. The external wall construction seems unusual. Starting from the inside there is plasterboard, a few cm gap with insulation material, plywood sheeting, another gap (can't see if there is anything in it), then the external block work.
I had been expecting plasterboard over internal block work, a gap and then the external block work.
The previous cabinets were screwed to the wall using standard wood screws which I think penetrated in to the plywood sheeting.
Does any one have more information on this type of wall construction?
Is simply screwing the wall cabinets to the wall with screws through the sheet plywood adequate?
If not what should I do?
Thanks

[KitchenGuy]

It's an early form of timber framed house which is one of the most commonest forms of house construction these days. Basically a timber house clad in brickwork or the likes. You can just screw into the ply or any part of the internal timber frame. One note of caution, depending on construction method, somewhere between the inner skin and the outer skin there is a waterproof membrane, usually visqueen, a thick form of polythene. It is the only thing keeping damp from the outside skin to the inner walls so be careful not to penetrate it.

[irongeezer]

Thanks