Have you ever taken a look at the foundation of your home where the siding ends and the earth starts? A typical foundation in this area is constructed with concrete masonry units. A mason will make that above grade exposed blockwork look good by parging it. Parging is the act of creating a covering on a vertical surface. The word parging derives from pargeting which is a technique for waterproofing or decorative plastering to a building’s walls dating back to the 16th century. However, it may have started way before then and lost favor.
The ideal parging for your foundation will be a mortar based product typically “Type N” or “Type S” mortar. Type N is a general purpose mortar and can be used above grade and Type S is a stronger product and typically used below grade. The mason will clean the wall thoroughly prior to painting on a bonding agent and then will trowel on two coats of mortar. He will wait for the first coat to cure prior to applying the second coat. Each coat is required to be 1/8 inch thick but a 1/4 inch per coat is recommended.
Not only does the parging enhance the look of your foundation it will fill any voids created during erection as well as create a weather barrier from rain and snow. It is not a dampproofing product but it does inherently give you some protection. You do not typically want to paint the parged surface because paint can crack and moisture could get in and have trouble getting out. This trapped moisture can give you problems over time. This trapped moisture could end up creating structural damage to your home’s foundation. If are going to coat with something be sure to understand the properties of the product you intend to use and how weather can impact it.
In addition, the masonry wall below grade shall be parged and then the contractor is required to provide waterproofing or dampproofing as per The International Residential Code Section R406. The type of “proofing” required will be determined by whether or not groundwater is present on your property. So this should cover your bases!