The article 'Cleaning and Repairing Stone' by Clive Richardson (aj 21.5.98) critically describes certain masonry repair techniques as 'spabbing'. While the examples mentioned may be an individual interpretation of spab principles of conservative repair, the work described is not the only approach to masonry conservation that the Society of the Protection of Ancient Buildings might consider, nor necessarily something we would endorse. The objectives of our principles are simply to minimise historic fabric loss and to repair honestly. Tile repair can be an effective way to achieve this, but is not the only way.
The final draft of the Code of Practice for Cleaning and Surface Repair of Buildings (bs 6270 Part 4), seen by the spab, and quoted as a key reference document by your article's author, has the following clause about tile repair:
'In particular circumstances, depending upon location and materials, the use of clay or stone tiles, which are usually bedded horizontally, may be appropriate for surface repair. The tiles and their mortar should normally be of lower strength and higher porosity than adjacent masonry and the repair may be left either visible or covered'.
This bs6270 clause originates from the spab. It does not excuse poor workmanship, nor advocate the insertion of dpc material, and it need not be visually obtrusive.
The society is surprised that the author makes reference to the spab without a clear understanding of our ideas. We also find questionable and over-simplistic some of the repairs guidance suggested elsewhere in the article. For an explanation of our qualifications and reservations about the article's comments on the use of water repellent coatings, cleaning systems, limewatering or grout, limewash and shelter-coat mixes please telephone the spab direct (0171 377 1644).
spab technical secretary