The U.P. is home to many historic commercial buildings. The stone or rubble foundations found in many of these buildings is a distinctive feature common in historic Upper Peninsula homes and commercial real estate alike.

Recently we were asked to perform a commercial inspection of a former grocery store built in 1890 in Marquette County. The 100+ year old mortared stone foundation of this property is a testament to historical craftsmanship and durability. However, as is typical of stone foundations of this vintage in the U.P., it has suffered the ravages of time.

As a home inspector, I believe that any commercial inspection (or home inspection) process should not only educate the customer about the condition of the building but also offer potential solutions to address any issues found. These may include both standard professional repair methods as well as preventive and maintenance standards.

If you are considering purchasing an older U.P. commercial building or home with a mortared stone foundation, be sure to look for signs of damage to the masonry when you view the property. The following points will give you a better idea of what can be done to repair such issues, as well as maintenance requirements for stone or rubble foundations.

Stone Foundation Repair Methods:

A crumbling foundation supporting an otherwise attractive building can make a prospective buyer think twice about a real estate purchase. However foundation damage does not mean a building is a lost cause. Even significant damage to mortared stone foundations can often be repaired. Here are some common stone foundation repair techniques you should be aware of:

Repointing:

Remove old, crumbling mortar and replace it with new mortar. This process helps to stabilize loose stones and prevent further deterioration.

Shotcrete:

For severely damaged sections, shotcrete (sprayed concrete) can be applied over a steel mesh framework to create a new, supportive wall. This method may alter the appearance but provides a robust solution for structural integrity.

Replacement:

In cases where sections of the foundation are beyond repair, replacing the damaged area with new concrete blocks may be necessary. This should be done by a professional to ensure proper support and alignment.

Key Maintenance Practices for Mortared Stone Foundations:

Maintaining the integrity of an older stone foundation requires regular inspections and timely repairs to address common issues such as mortar deterioration, moisture infiltration, and structural shifts.

Regular Inspections:

If you have a stone foundation, we highly recommend inspecting your foundation yearly. This is something you can do on your own to identify early signs of damage such as cracks in the mortar, loose stones, and water infiltration. Look also for uneven floors and jamming doors or windows, which can indicate foundation issues. You can find a more detailed explanation on how to conduct an annual foundation inspection here.

Moisture Control:

Moisture is a primary cause of mortar decay and stone displacement. Therefore it is essential to ensure proper drainage around a stone foundation. Use gutters, downspouts, and proper grading to prevent water accumulation near the foundation.

Repointing:

Repointing involves removing deteriorated mortar and replacing it with new, compatible mortar. This process should be done every 15-25 years to maintain the foundation’s stability. Use lime-based mortar for exterior repairs and pre-mixed rigid mortar for interior repairs to ensure compatibility with the original materials.

Vegetation Management:

Keep trees and large plants at a safe distance from the foundation to prevent root damage. Roots can exert pressure on the foundation, leading to cracks and shifts.

Proper Ventilation:

Ensure that crawl spaces and basements are well-ventilated to reduce dampness, which can accelerate mortar decay.

Avoid Chemical Exposure:

Limit the use of harsh chemicals, such as de-icing salts, near the foundation as they can damage both stone and mortar.

Preventative Measures for Stone Foundations:

I can always tell during a commercial inspection whether a foundation has been treated to regular maintenance. Just a little bit of maintenance over time adds up to a lot of savings when you consider the cost of major stone foundation repair. And that is if you can even find a qualified mason in your area!

It is important to perform annual maintenance to address minor issues before they escalate. This includes repointing small cracks, resetting loose stones, and ensuring proper drainage.

Finding the Right Professional Support (Mason or Engineer vs. Commercial Inspection)

By adhering to these maintenance practices and repair methods, even a 100-year-old or older mortared stone foundation can continue to provide reliable support and preserve the historical value of the property for many years to come. As most property owners cannot be expected to have the skills needed to maintain or assess a stone foundation on their own, it is important to have the right professionals on hand for your needs.

  • For significant repairs or structural concerns, it is best to consult a professional mason or structural engineer. Their expertise is crucial in maintaining the foundation’s integrity and ensuring the safety of the building. They can also conduct a detailed inspection and assessment for you, including an estimate of repair costs.
  • For initial assessment of the condition of the foundation (and all other aspects of the building), you need a certified home inspector qualified to perform a commercial inspection.

At U.P. Home Inspection, we see and inspect stone foundations regularly, both in commercial buildings and residential homes. We pride ourselves on taking the time to educate you about any issues that show up during a home or commercial inspection, and how they may affect your purchase decision. For property owners, we also offer maintenance inspections that can help you identify existing and/or potential issues and create a plan of action to address them.

Need a Home or Commercial Inspection?

We are happy to help. Call us directly at 906-360-3879 or schedule your home or commercial inspection here today.