Parging or Tuck-Pointing
For more information, visit our Stone Foundation and Structural Repair Page.
Stone foundation, the most common basement built before 1915, is a concern for homeowners of old homes. Homes that are a hundred years or older foundation were commonly made from fieldstone and limestone. Basements were made by stacking stones and using mild mortar and gravel to bond the stones together. As the stone foundation aged, the mortar deteriorated, the mortar turned to powder, and the wall lost strength.
Old Stone Foundations
In many old stone basement foundations, interior drain tile was not installed, which can cause the basement to be wet or damp. Many old stone foundations built before 1915 were without footers; they made them on packed soil. Digging down on the outside of a stone foundation loses the support of dirt that helps hold it up. If you dig down on the outside of the foundation of a stone foundation, it can cause the stones to fall out or even collapse the wall.
Basements appropriately designed with correct footer and foundation walls are often strong enough to hold up against the forces of nature for many years. The combined pressure of gravity, soil swelling with water, freezing, and thawing create hydrostatic pressure. Hydrostatic pressure and tree roots are forces that continue to excerpt pressure and gain entrance into your basement.
A visual inspection will disclose gaps in the joints, crumbly mortar, bulging, bowing shifting, or settlement that may require a home foundation repair.
The Need for Re-Pointing/Parging/Tuck-Pointing
Moisture migration will inevitably cause the mortar to deteriorate and expose the stones. When this occurs, re-pointing or parging is needed. If enough of the old mortar falls out between the rocks, they will shift around. A home foundation repair would be necessary if the sandy, crumbly mortar falls out, the stones also will likely fall out.
Proper Basement Drainage
Maintaining the proper soil pitch around the foundation is equally essential to correct any negative pitch. Proper basement drainage around the outside of the basement foundation's perimeter is necessary to avoid hydrostatic pressure. When properly grading around the foundation, window wells may need to be added in front of each window to keep the window from being buried and effectively raise the topsoil grade around the home, shedding water away. The ground and decks or concrete patios adjacent to the foundation should have a positive slope away from the house foundation. Roof water should collect in a well-maintained gutter system with downspouts and discharging away from the foundation. Sump pump discharge lines also need to be extended out from the home foundation.