LPS high rise blocks comprise precast reinforced concrete walls and floors stitched together with in-situ concrete joints. These types of blocks were perceived as the answer to many Council housing problems in the 1960s, but the sudden collapse of Ronan Point as the result of a gas explosion in 1968 led to a radical rethink of the acceptability of this construction method. Design parameters were immediately changed, and many blocks already constructed had to be considerably strengthened, while others had their gas installations removed. Initially only blocks in excess of six storeys were required to be strengthened to minimise the risk of progressive collapse, but some years later (following new building regulations) it was changed to five storeys and above.
To this day many problems still exist with LPS blocks, as some seem to have “slipped through the net” and remain unstrengthened, while others were either not redesigned correctly to meet the new mandatory regulations, or strengthened adequately in the immediate post Ronan Point era.
Defects that have arisen and necessitated AWT’s involvement have generally, but not exclusively, been concerned with defective/inadequate wall to floor joints and inadequate tying of the outer skin of flank walls and spandrel “sandwich panels”.
AWT have extensive experience in remediating these defects, working in close connection with structural engineers to develop repair strategies and install strengthening brackets and ties, and stitching together of walls and floors to resist accidental loading. This work is always undertaken with care and attention to detail by trained and highly skilled operatives using specially designed equipment and supervised at all times by visiting engineers.