Adjoining semi-detached properties were built as part of a small development of six, 3-bedroomed affordable properties circa 2006 for Shropshire Council. Since construction the properties had significant repointing works undertaken at regular periods.
Thomas Consulting was contacted by Shropshire Council to initially undertake a visual structural inspection of the properties and subsequent monitoring to determine if the cracking was progressive. The scope of work developed to include ground investigation to determine appropriate underpinning remedial works.
The inspection showed cracking to the external leaf of 20mm, monitoring confirmed that the cracks were progressive. Trial holes were undertaken to demonstrate the depth of the existing foundations and near surface soils in the garden. The trial holes indicated that the foundations were to approximately 1.0m depth to clay soils with water seepage from below the property. Soil testing was undertaken showing that the soils were high plasticity. By talking with local residents, it was understood from neighbours that large Leylandii trees had been removed from the site; therefore, the foundation depths were inadequate. Suitable load bearing strata was identified at 4m depth; therefore, traditional underpinning was not an option. Water seepage was found to be a damaged water supply pipe to the properties; Helifix micro piles were utilised to underpin the property to a depth of 6m.