Tilt in Co. Clare

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Tilt is a term that is loosely used in the construction industry but it in fact a very rare occurrence.

When buildings constructed on traditional strip foundations move, the building will become distorted and cracking will occur. This cracking is usually very noticeable. However, in raft foundations, which are much stiffer, the failure mode is quite different as the whole of the building may move as one unit without any obvious signs of distortion. This is the definition of tilt. Of course, if movement progresses, occupiers will notice floors becoming more and more off level or doors swinging open.

The Building Research Establishment, a UK independent research organisation, has offered guidance in relation to acceptable levels of tilt for low rise housing but it is noticeability of 1/250 to 1/200 where problems normally begin when tilt is identified. At this point, investigation works should be completed to determine cause and monitoring considered, particularly if the tilt has surpassed 1/200. If the building has reached a tilt of 1/100, then some form of remedial action is required and feasibility comes into play. Therefore, it is important to address the concerns as quickly as possible.

This building in Co. Clare has in fact reached the value of 1/100 and underpinning works is required. The cause of the movement was identified as a leaking supply pipe in the kitchen. The design approach becomes more challenging as the building is sited in the middle of a terrace.