Precast Concrete and System Building

In 1960s and 1970s the walls of multi and deck access blocks were formed from precast concrete panels and concrete floor slabs. The system was used in three and four storey walk up flats, 10 storey tenements with lifts, stub blocks and deck access housing as well as high rise buildings.

In the 1960s, floors were generally poured concrete slabs. Floorboards would be laid on battens and the battens laid on quilt insulation. In the 1970s, large precast concrete planks were often used to make separating floors. These had joints which had to be filled and levelled with screeding. Floating floors on padded “resilient” cradles or battens were used to level the surface and reduce impact noise.

The underside of concrete ceilings would be strapped with timber battens and sheeted with plasterboard.

Problems – damp and cold

  • rain can be blown through the wall panel joints (including from below)
  • lack of insulation at the panel edges causes “cold bridging” where condensation dampness can form.
  • overcladding may have missed areas around pipes and services leading to condensation and mould

Solutions – damp and cold

Most multi-storeys have now been upgraded and overclad with insulation and rain screens (or demolished!).

Problems - noise

Concrete floors generally provide good noise insulation however problems can occur from:

  • slab joints not fully grouted and sealed
  • slabs not built into the perimeter walls causing flanking sound
  • junctions between the slab and the wall may have been poorly filled
  • resilient quilt to floating floor has deteriorated.

Solutions - noise

It is often hard to decide what the problem is and investigations may involve opening up the floor and walls to find out about the construction.

  • flanking sound, can be reduced by building an independent wall lining 20mm (1”) away from the affected wall.
  • install new ceilings using acoustic quilt and resilient metal battens fixed to the underside of the existing ceiling to hold plasterboard
  • a bonded soft floor covering over screeded concrete, may help with impact noise.
  • install a shallow platform floor if space permits.
  • replace the existing floating floor with resilient battens and a new floor finish.