What is a Measured Building Survey, and why is it different from a normal survey?
When you think of a building survey, you usually think of the type of survey that a buyer may carry out before purchasing a property. This is a general look around a property, to identify any likely problems, such as damp, subsidence, defective wiring, and condition of the roof or other issues of that nature. Basic measurements may be taken, and a floor plan may be drawn up, but in reality this is not a particularly accurate plan, and it is not suitable for anything other than confirming rough dimensions.
On the other hand, a measured building survey is an extremely accurate way of measuring the entirety of a building. It is carried out in two stages; first an engineering surveyor will visit the property and carry out a scan with a laser scanner. The scanning technique creates a cloud of virtual reference points and measures the distances and elevations between them. This information is then transferred to the second stage where the engineering surveyor will use sophisticated software to process the raw data from the scan to produce a very accurate plan of the building. Unlike normal surveys, this can produce not only floor surveys, but also internal and external elevation plans, which identify the location of sockets and light switches, the size and height of doors and windows, including the dimensions of their reveals and soffits, and the precise angles of internal and external corners. It can also reveal architectural features such as cornices and corbels. In the correct hands this technique is 99.9995% accurate, and the plans can be used to produce 3D images as well as more traditional 2D plans.
Why do I need accurate plans?
If you are considering alterations or extensions to a property there are several reasons why you should have an accurate and detailed property plan. One of the most important reasons is that the details you provide to the planning authorities and any construction contractors forms part of a legal contract. If you provide inaccurate information at the planning consent stage, it can leave you open to enforcement action by the authorities. This is especially important if you are dealing with a listed building or a property within a conservation area, as the restrictions are even tighter, and accordingly the accuracy of your information needs to be greater. At the construction stage, inaccurate plans can leave you without recourse to the law if your contractor fails to comply, as he can cite poor quality information as a defence.
In these circumstances you cannot rely on architects’ drawings. There are a number of reasons for this, but in fact most properties in the UK do not actually have architects’ drawings. Despite notable exceptions, the construction of property is highly standardised, and most buildings are built to “pattern book” designs, where one plan encompasses a number of properties. Even if architects’ drawings are available they rarely accurately reflect the property as it stands. The cumulative effect of tolerances in construction materials and techniques mean that even in a new property, the dimensions of the finished product can vary considerably from the original design. If you add to this the effect of thermal movement and settlement over a number of years you soon realise that the original plans are only a rough guide to the current building as it stands.
These are the main reasons a simple floor survey is no longer sufficient. If you are planning alterations or extensions it is best to have a measured building survey.