We can undertake traditional underpinning works where loading and depth requirements are non critical. In the example given below we were required to support a brick outbuilding attached to a habitable property. The property is located on a sloping site in heavy clay soils and the outbuilding had started to rotate away from the house creating severe vertical cracking (up to 40mm wide) between the two structures. The repair strategy consisted of underpinning combined with Thor Helical Remedial Crack Stitching to tie the outbuilding back to the main structure, and replacement of clay sub-surface drains with a uPVC equivalent.
First concrete pad complete with adjacent hole for second pad being excavated
Second pad excavation through very stiff clay and chalk matrix
Excavation completed through to parent chalk material
Excavations revealed that the major cause of subsidence was the result of a sub-surface drainage leak removing fines from the soil reducing the outbuildings foundation capacity to support its loadings. Foundation depth for the outbuilding was also found to be of a non-compliant with current Building Regulation requirements. Drain pipes were found to be of clay vitrified type that had cracked and leaked over a period of time. Earlier inadequate repairs of these revealed that the problem had been ongoing for some time. A combination of these factors resulted in a rotation of the outbuilding away from the main house resulting in the large vertical crack between the two.
Original cracking problem at junction of outbuilding East flank wall and house
Original problem at junction of outbuilding West flnk wall and house
Thor Helical Remedial Crack Stitch installed in East flank wall ready for repointing
Thor Helical Remedial Crack Stitch installed in West flank wall ready for repointing
Completed underpin with new footpath in place. Just relaying of patio slabs and repoint of East flank wall to complete
Completed West flank wall with repointing and patio slab relay to finish job
In addition to the underpin works a structural repair was carried out above the Kitchen window opening to repair crack brickwork. This photograph shows a Thor Helical Remedial Masonry Beam in place alone with cracked bedjoint mortar rakeout ready to receive a repoint
