Maintenance & Cleaning
CMU, like Brick is relatively maintenance free, but occasional cleaning, spot checks for water damage, and repointing are necessary in order to ensure long-lasting structural integrity.
Moss, mild, mildew
If a particular side receives little to no sunlight and the nearby vegetation is damp, be on the lookout for moss, mold, or mildew growth. A solution of one cup of bleach mixed with a gallon of water can be applied with a scrub brush can be used to clean most problem areas. Use a natural or synthetic bristle brush (wire brushes leave traces of steel behind that will rust and discolor).
Water damage
Water damage is caused by one of two conditions: splash back or rising damp. In splash back, rain continually beating against the block soaks into the mortar, causing the mortar joints or the block to crack. Rising damp results when ground water seeps up from below, leaving behind what is called a tide line. The moisture above the tide line will eventually evaporate, but the salt crystals that remain will, over time, cause the block and mortar to break down. Freezing and thawing cycles can accelerate damage to water-soaked block, so repairing problems early will prevent more extensive repairs in the future. Look for water damage on an annual basis, and budget for some possible repointing every five to ten years.
Repointing
Repointing is necessary in places where the mortar joints have become soft or the mortar itself is cracked or damaged. The damaged mortar is removed carefully so as not to disturb the surrounding brickwork. Fresh mortar is applied in layers. When repointing, the depth of the new mortar should be twice the width of the mortar joint. Mortar applied directly to the damaged surface will not hold up.
Cleaning
Once a year use a garden hose, with a spray nozzle, or a spray bottle to remove any loosen dirt.
- If your block is dusty or dirty, use a scrub brush to scrub at any surface-level dirt or dust. Avoid wire brushes, which can leave metal scratches on the brick and cause rust or corrosion over time.
- Spray the entire surface of the CMU wall with water first.
- Use dish soap and scrub the block with a brush or spray the soap on the wall then scrub it with a brush. Allow the soap to sit on the wall for 5-10 minutes.
- Use a hose to wash the wall off. Make sure all the soap has been washed off.
Be aware that power washing is a science. If done incorrectly, it can damage the block, blast the mortar off, and create future water damage. If power washing is needed, then always get a professional who can warranty the work and insure the block won’t be damaged. If any are, then their insurance should pay for replacement. Always inspect the work after it’s complete, before issuing final payment.