• Blocks stacked on site and been used in the building should be kept as dry as possible.
  • Do not rake out the joints when pointing, use a half round tool so that the mortar remains on the front edges of the block. This method is better for waterproofing.
  • Any mortar that spills onto the face of the block, allow to partially dry before trying to remove, use a scraper and nylon brush with mortar-cleaning agent from a bucket.
  • Start off with a weak solution and increase the strength until the ideal dilution is found.
  •  Do not use a hose pipe on the block work, a high pressure water cleaner may be used as a final clean provided the correct nozzle is used and there is minimal water penetration into the block.
  •  After the block work has been cleaned and allowed to dry waterproof by using water repellant, a siloxane product or similar.


More guidance on building with concrete blocks can be found in the masonry manual obtainable from the concrete manufactures association or on their website:

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