Douglas Kent, Technical and Research Director at the Society for the Protection of Ancient Buildings (SPAB) offers his advice on when you should restore timber beams and when you should replace them.

Old beams should not be needlessly replaced or their surface finishes removed without careful consideration. The replacement of beams will nearly always reduce the special interest of an old house. Sandblasting or aggressive cleaning not only damages the wood but can destroy traces of early decoration.

Repair

Old beams are robust by and large but may suffer decay (particularly at their ends) or distortion. While conventional carpentry techniques employing well-seasoned, matching new timber will frequently be suitable to address these defects, the use of steel may be justified where it allows more of the existing beam to be retained than would otherwise be possible. Use resins and consolidants, but only with great care.

Reveal

Seriously consider whether exposing a beam is really appropriate and remember listed building consent may be required. Little is gained, say, from uncovering a beam boxed in during the Georgian period if the rest of a room features modern finishes. Generally, cleaning is best achieved by simply brushing beams or washing them judiciously with warm water. Should you decide to remove an inappropriate black finish, chemical strippers can work well (although it is important to first test areas).

Replace

The use of new beams may be justified in certain circumstances, perhaps to replace unsuitable modern ones or offer an immediate impression of characterful comfort when building an extension. Good quality European green oak is a sound choice. If you feel it necessary, beams can be treated with a beeswax and turpentine polish or micro-crystalline wax. This is often preferable to polyurethane varnish, stains or modern gloss paint.

Three of the best timber beams

Reclaimed beams Ready-aged new timbers
Reclaimed beams 1. Instant character: Lawsons Timber stocks reclaimed beams to buy off the shelf, from £150 (01704 893998; traditionaltimber.co.uk).
2. Loft extension: Oakmasters’ ready-aged new timbers cost from £30 for a 3m, 75mm beam (01444 455455; oakmasters.co.uk).
3. Vaulted ceiling: Traditional Oak and Timber Co’s reclaimed beams cost £45 + VAT per cb ft (01825 723648; tradoak.com).

A brief history of timber beams

exposed beams’ or ‘low-beamed ceilings’, so popular with estate agents, convey an endearing picture of ‘home’ to many people. A beam – a principal horizontal load-bearing member in a building – typically spans from wall to wall. Historically oak was the traditional native species chosen for beams in the United Kingdom, although elm, ash and other types of timber were also used.

Medieval timber beams supporting the upper floors of houses were exposed to view. In higher status rooms, they might be moulded or ‘chamfered’ (have their angles splayed off ), with the chamfer terminations (‘stops’) forming different patterns at the beam ends. The differing details can indicate the approximate age of a beam – although not necessarily a ceiling itself, because beams were sometimes re-used. Traces of plain or decorative paint finishes may also survive on old beams, although might not be readily apparent.

Ornamental plaster ceilings were popular by the late-16th century and could hide beams as well as the joists between them. By the 18th century, exposed timber beams were rare in all but the humbler houses; where not concealed completely, they were normally encased in boarding or plaster. However, come the 19th and 20th centuries, they were not only being exposed once again but also blackened artificially. More recently, the trend has been towards removing black coatings, which can prove a painstaking, messy job, and lightening beams, for instance, with liming wax or casein-based paint.

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