cracked brick investigations

Excel Building Surveying Ltd have recently been commissioned to complete a number of investigations to determine the cause of cracking within blocks of flats on the South coast, a domestic property in Twyford and a London School. The first included determining the condition of lintels and the cause of cracking to two blocks of council owned flats on the South coast. Cracking had been observed to brickwork facades about window frames, balconies and lintels. The client required data regarding the cause of cracking in order to guide their future maintenance regime. A number of defects were observed by both borescope inspection and localised brick removal by Arbortech. Defects included haphazard blown cavity fill insulation, a number of wall ties corroded through, debris filled areas, a lack of stop ends to cavity trays. The reinforced concrete boot lintels were however found to be in fair condition and the observable cracking to the external faces was confined to a thin render coat only. This positively impacted the projected budget for future maintenance requirements. The second involved completing an inspection of the cavity to a domestic 2-stoey detached house in Twyford. The building is timber framed with a brickwork façade, built on sloping clay in the 1980`s. Cracking had formed at both corners of the downhill gable and the cause was presumed to be from clay shrinkage following the 2018 summer heatwave. A Cavity inspection using both borescope and localised brick removal showed the cavity to be relatively clean with no obvious projections which may have been contributory to the cracking. The repair advised was localised underpinning using helical piles to a depth beyond the shrinkable zone of the clay substrate. The third was to the walls and floor slab of a London School. The site was built on a slope and the floor in question is approximately 1300mm above external ground level. Internal brickwork walls were found to be calcium silicate bricks with clay facing brickwork. The surveyor completed breakouts of the floor slab where the screed was found to be cracked however the underlying reinforced slab did not have reciprocal cracking. The underlying fill material was exposed and found to be wet despite being 1300mm above ground level. It was determined that defective drainage from the adjacent kitchen was probably the cause of elevated moisture levels and that the calcium silicate bricks were expanding differentially to the external clay bricks due to the wetting. The differential movement was causing cracking to the external walls. The cause of the screed cracking was not determined however the screed was found to have variable depth potentially cause a fracture plane in the event of movement (possible heave of the wet fill material). Excel personnel have been involved in testing bricks, mortars and renders on many projects. Our partners are able to complete chemical analysis to confirm materials conform to building specifications and current standards.