Heritage Building Materials

Emily Brooks looks at ideas for putting traditional techniques to work in houses old and new
by Emily Brooks
26th November 2012

Building methods that have lasted down the centuries have done so for a reason: natural, durable and aesthetically appealing, they result in homes that have an intrinsic affinity for their surroundings. In older homes, using methods such as lime mortar rather than concrete is necessary to prevent damp, and like-for-like repair is always the best course.

Traditional techniques have much to offer new-builds, too. Certain construction methods partner ‘heritage’ finishes very well – green oak frames with lime-rendered walls, for example, or reclaimed brick masonry with decorative flint render. They can give an impression of a building that nods to the past without resorting to pastiche. Using an ancient construction method or decorative finish need not result in a backward-looking building: some of the most exciting contemporary designs successfully combine a modern profile with materials that have been around for centuries.

Brick

Period bricks have imperial, not metric, sizes and were softer, usually laid with lime mortar. Modern cements can damage these softer bricks, and should never be used to repoint them. Colours change locally from yellows to buffs and reds, as do their properties – depending on their raw materials and how they were processed. Hand-made or hand-finished bricks give an effective traditional look, but using them will push your budget up.

For refurbishments, SPAB recommends only replacing bricks that have been severely damaged. Then use new ones that will mellow in time, rather than reclaimed ones. It is cautious about using reclaimed bricks since they could be damaged or unsuitable for external use – but there are plenty of reclamation yards supplying second-hand bricks if you do want to go down this route.

Earth & Clay

Made from a mixture of earth, straw, dung and animal hair, cob buildings are predominantly found in Devon, but they do crop up elsewhere in England, and are once again being used to build by a select few. The cob is mixed on site, laid in layers and, when dry, finished with lime-wash. You can buy cob bricks to repair or rebuild an earth building, as well as a wide selection of natural decorating products such as lime, from Mike Wye & Associates.

Clay has been used for centuries for render, plasterwork and as a base for paint. Like lime, it offers a porous, breathable finish. You may find it for free in your garden. However, it is not nearly as hardwearing as lime, and will need additional weatherproofing; generally, clay external renders are not recommended because our wet climate means they could get saturated and, in extreme cases, wash away.

Lime

Lime was an essential building material until the turn of the 20th century. It was used for mortar to bond bricks, for render, limewash and plaster for walls and ceilings. Its key property is that it is permeable, allowing a building to ‘breathe’ and not trap moisture and air within, thereby preventing damp.

For modern uses, lime render works eminently well with traditional wood frames, especially green oak, as well as re-rendering old walls (as long as they’ve not been painted). Limewashed walls, either in natural white or with pigment added, give a deep matt finish and a pleasing multi-shaded appearance – the colour subtly changes according to how much moisture is retained in the wall behind it.

As a raw material, lime is either hydraulic (in powder form) or non-hydraulic (sold as either ‘hydrated’ or ‘bag lime’, or as a thick lime putty, in which case it will be in a tub). Usable lime putty can also be mixed from the hydrated powder. Formulations vary depending on use, and mixing requires skill to get the right blend for each job, with sand and even animal hair being added depending on the application. Lime is highly caustic and its reaction with water can be violent, generating significant heat, so protective gear is essential. It also needs protection from frost while it cures.

Stone

From limestone and sandstone to flint, stone has long been an indispensable building material. However, cost can be high for new builds, so you might want to consider reconstituted or imitation stone as an alternative. Stone was traditionally quarried locally, and grades and colours vary widely, from the honey-toned Cotswold stone that gives the area its enduring appeal to Cornwall’s tough granite.

In the past, flint walls could be structural as well as decorative, but due to Building Regulations’ requirements for cavity walls, flint is now usually knapped to give it a clean face and used as a form of cladding, embedded in render. “It’s important to get the style and type of flint right, to match the region and historical context,” says flint building expert David Smith. “A smaller, cottage-style build might have been built using simple field flints, whereas a bigger, high-status home might use more decorative knapped faces.”

Timber

Until the arrival of brick, timber frame was the dominant build method, and many concentrations of venerable buildings survive in areas such as Lavenham, Stratford-upon-Avon and Ludlow. It is enjoying a greater resurgence than any other heritage building technique, with many companies specialising in timber frame, green oak and post-and-beam builds. By their nature these buildings have a natural affinity with other traditional materials such as lime plaster.

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