Stone Foundations – Some Things to Know

Stone foundations were standard fare in houses built before World War I. Today, they’re a source of frequent worry to buyers and owners of old homes.  But are they really something to be concerned about?

Stone foundations require some extra attention considering that they are the foundation of your home.  If an older house suffers from sloping floors and cracked plaster, it’s reasonable to suspect foundation failure as the likely cause.  A brief visual inspection will quickly disclose bulging, bowing, shifting or settlement of a stone foundation. If you find any one these conditions, you should call in the services of an experienced mason.

Mortar is flaking away from this stone foundation

Re-pointing is one way of adding more support to the home.  A mortar coating on the interior foundation helps keep the stones in place, but it will eventually flake off from moisture migration, revealing the surface of the stones. As this coating continues to erode, the soft, sandy mortar in between the stones begins to fall out. When this occurs, re-pointing is needed as soon as possible to refill the voids where the old mortar fell out.

When re-pointing the exterior face of an old-house foundation, mortar needs to be softer than the surrounding stones or bricks. To avoid perpetual re-pointing, you will need to finish with a complete top coating.This top coat does not have to look like a stone artisan’s creation: It merely has to serve the purpose of keeping the old mortar in place.

Re-pointing is a very important part of maintaining your beautiful, historic home, but it is also important to note that the moisture penetration eroding your mortar can become a serious problem.  In excess, it can also lead to serious conditions like pressure against the foundation and frost heaving in cold winter climates.

To avoid these conditions, you need to maintain proper drainage around the perimeter of the house:

• Soil and surfaces of patios and walkways adjacent to the foundation should have a positive slope away from the structure.
• Roof run-off should be collected in a well maintained gutter system and extensions should be provided on the downspouts.
• The discharge from sump pumps, used in basements where water collects, should be directed well away from the house.

Irvine Construction is Maryland’s Premiere Historic Home Remolding and Construction Company. Contact us today to learn more about our process, our past projects, or to inquire about a potential renovation project.