C O N T E X T 9 9 : M A Y 2 0 0 7 total overall thickness of no more than 250mm. Voids occurred throughout the height of the rear wall of the extension. In another case a 19th century wall (pictured below and p9 top), some 450–500mm thick, had been faced with a solid full-brick wall without any bonding into the face behind at all. There were fears that the outer face would fall away when heavy building construction started on the adjoining site. The method for dealing with such situations involved providing some temporary support for the external wall face. The usual way of doing this would be to use extensive raking shores, as indeed was the case originally when I looked at the brick wall. Our practice has developed a method for clamping walls through their thickness. We have used vertical timbers on the external face with holes and then bolts through the wall into further timbers internally, thus clamping the wall to prevent its collapse. We have used this system in very much more difficult circumstances to restrain the external faces of flint and stone buildings. The photograph on p9 shows a wall which has bulged away from its original position, with cracks forming at the back of the quoin stones. Initial ladder access to this wall, using the hand-banging technique, indicated that the wall was hollow behind its front face. It was held together simply by the hard mortar holding the external stones in place. The builder involved with this project was of the opinion that it would be necessary to take the whole wall down and rebuild it. He refused to carry out the work based on the clamping method. I appealed to the Engineering Division of English Heritage, which sent one of its engineers. He agreed with my clamping approach.Throughout the height of The gable end of this house was constructed out of two thin skins of rubble flint. This 19th century wall had been faced with a solid full-brick wall without any bonding. Clamping timbers through the wall’s thickness prevents collapse temporarily. The bulging wall was hollow behind its front face.
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