Sealing a Cinder Block Retaining Wall

Cinder block is lighter than a solid concrete block as the aggregate that goes into it is cinder ash made from coal, not gravel. This makes it very porous and a less desirable building material for a wall that must withstand the elements -- unless it's well sealed. A retaining wall will seep moisture from the soil banked behind it and must get a good coating of a strong sealant, or paint, to keep it in top condition, just as a house basement of cinder block needs proper sealing to keep it waterproof.

Things You'll Need

• Liquid dish soap
• Bucket
• Sponge
• Stiff cleaning brush
• Patching compound
• Putty knife/trowel
• Sealant or paint
• Coarse brush

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Instructions

1. • 1

     Wash the wall with a mixture of liquid dish soap and water in a bucket and sponge off all dirt before letting the wall air-dry. Use a stiff brush on stubborn dirt.

   • 2

     Fix any holes or cracks in the wall with concrete patching compound applied with a putty knife or trowel.

   • 3

     Apply sealant or paint with a coarse brush -- no need for finesse. Brush it on with short strokes for consistent and adequate coverage. The thick coat will take longer than normal to dry.

   • 4

     Wait 24 hours for the coat to dry and cure then apply a second coat if necessary.