Geobear stabilised the flats affected by subsidence
Background
Paradigm Homes is a charitable housing association who manage over 15000 properties in the south-east. Two flats in one of their properties in High Wycombe had suffered from severe structural movement during the extended dry spell in 2018-19, which meant the tenants had to be re-homed.
The property was part of a block used to house elderly residents and had suffered from a combination of a settled concrete floor slab and subsidence to the rear perimeter wall. The entire slab in the flats at the back of the building had sunk, and the perimeter wall was affected by clay shrinkage resulting in severe cracking.
Customer alternatives
The extent of damage would have necessitated extensive repair works. The floor slab would need excavating entirely before a new sub-base and floor could be installed. To stabilise the perimeter wall underpinning could have been completed, although this would have taken up to eight weeks. The extended programme times made these options undesirable for Paradigm; they required a fast solution to minimise the disruption to residents and keep the flats occupied.
Cracks to walls
Why Geobear
In comparison to alternative methods, the Geobear solution is a fast, permanent repair. Stabilising a perimeter wall usually takes 1-2 days depending on the ground conditions, as would slab stabilisation works. Timescales are critical for housing associations due to the costs associated with re-homing residents and holding empty stock. On average, the Geobear solution saves up to two months on alternative methods.
Unlike underpinning, with Geobear there is no excavation required, this drastically reduces the time for a wall to be stabilised. The process leaves no mess with gardens and communal areas are unaffected. Furthermore, there is a minimal plant or enabling works meaning residents in adjacent flats are relatively unaffected.
Geobear Solution
Self contained Geobear units
For the Penn Mead flats, Geobear provided a solution that would stabilise both the external perimeter wall and concrete floor slabs within one week.
For the perimeter wall, the process required the injection of an expansive geopolymer material into the ground beneath foundations at a depth determined by ground investigations. In this instance, we treated 26 linear metres to a depth of 2m below the foundation.
The injections are made at 0.5-meter centres along the length of the wall; our specialist geopolymer material expands in the ground filling fissures and stabilising the area from any further movement.
Our slab stabilisation work followed a similar process, using site data we designed a solution whereby material was injected 750mm beneath the underside of the 10x10m slab. The material is injected through drilled holes set in a grid pattern across the affected area. The geopolymer expands beneath the slab filling voids and creating a solid base for the slab.
The Geobear solution for was completed within five days and we provided an insurance backed ten-year guarantee and a certificate of structural adequacy. Flats 4-5 Penn Mead could be handed back to the client to allow the residents to return to their property within weeks, rather than months.
Customer testimonial
Geobear provided stabilisation works to the concrete floor and perimeter wall, which they delivered within one week. The alternative would have been a rip out of the flooring and underpinning the perimeter wall, requiring elderly residents to re-homed for 6-8 weeks.
I’ve used Geobear many times over 30 years, they have provided fast and permanent stabilisation solutions without fail. I would not hesitate to recommend to housing associations.
Tony Parker, Paradigm Homes
