How strong should the mortar be for re-pointing brickwork FROM: John Bleackley (Surrey) What mortar should we use ?
Our property was built in 1878. A recent survey pointed out that repointing would be necessary. Unfortunately sometime in the past all the exterior brickwork has been painted. We have been advised that the paint is several coats deep and sand-blasting and chemicals may cause damage to the bricks. We have not been able to find a contractor that will work with lime-mortar and so we have opted for a 4:1 sand cement mixture – will this be suitable? What type of paint should we used to recover the walls? John Bleackley If your house was built in 1878 it is likely that the original mortar was bound with an early form of cement, but the basic material is sand and lime and any repointing should never be in anything as dense and strong as a 4:1 sand cement mixture. I would advise your builder to make a carefully measured 5:2 mixture of washed ‘screeding sand’ : lime; mix this in a tub really well using a power-drill driven plaster mixer, usually obtainable from your local Builders’ Merchant or
