Directory of Traditional Building Skills - Mourne Heritage Trust

13 SPECIALIST SURVEYS & PHOTOGRAPHYAn accurate and appropriate survey of any building is the basis for informed decision-makingon a project and is usually the first step in establishing the nature and extent of the workrequired. Surveys range from simple recording in plan, section and elevation, to highlytechnical, non-destructive techniques to locate hidden problems.For most buildings, a traditional, measured survey will be sufficient but care must be taken notto overlook important details. Few old buildings are true and square, and it should not beassumed that rooms are perfectly rectangular – a series of diagonal measurements will give anaccurate picture of the real shape of the spaces, both internally and externally. When extensivework is planned, it is important to record the size, shape and location of all interior fittings suchas skirtings, architraves, dadoes, cornices and other mouldings. Once demolitions commenceit is easy to forget exactly where such items belong: labelling each piece of joinery as it is takendown helps to prevent mistakes later.Rectified, or corrected, photography can be a valuable tool for recording the elevations of largeand complex buildings. At its most refined, this technique is called photogrammetry, where thephotographic information is stored on a computer disc and used to generate highly accuratedrawings in two or three dimensions.Other tools, such as X-ray, infra-red and ultra-sound can be used to detect hidden problemssuch as voids or corroded metal fixings within the fabric of the building itself. The mostcommon are magnet-based ‘cover meters’ and impulse radar. The successful use of thesetechniques requires specialist advice, and they are normally only employed on the mostintricate and important of structures where the high cost can be justified. However, such costsmay be offset by the early identification of problems before they become serious defects,requiring major intervention to remedy.Access for surveying is often a problem and the cost of scaffolding can greatly outweigh thecost of the survey. Mobile hoists are in general use, but for very awkward buildings, ropedaccess techniques are often more effective, allowing even the most hidden parts of a buildingto be thoroughly investigated and recorded.133