The Pros and Cons of Houses with Preserved Wood Foundations in Canmore

If you're in the market for a home in Canmore, Alberta, you may come across houses with preserved wood foundations.  In a recent purchase, I helped my Buyers navigate a preserved wood foundation that wasn’t disclosed in the listing as it is a blended foundation with a concrete wall at the front of the house but transition to preserved wood in the sides & rear wall of the home, an understandable mistake to have made but an important disclosure to have stumbled upon for my Buyer.  Luckily, we had a home inspection condition and worked with Adam of Homestead inspections, who identified preserved wood in a small crawlspace area AND the there was moisture present in the rear wall of the house.  For many Buyers, this would have been deal breaking, a non-waiver signed and delivered before the home inspection was even finished.  My Buyers however wanted to continue to pursue the home but obviously needed more information in the evolving situation so we extended our condition date and got a foundation specialist in to make a recommendation.  In this case, with the slope of the lot and some exterior landscaping features, it appears to be a drainage issue where water was pooling in one area against the foundation wall and it’s suspected no weeping tile is present because it wasn’t needed for code when the home was built so there is nothing encouraging water to move away from the foundation wall.  The wall will need to be re-damp proofed and a sump pump installed if no weeping tile is found but once the repairs are made, there shouldn’t be any more cause for concern and after some re-negotiations, my Buyers are excited at the memories they and their family will make in their Canmore home.

These foundations have a unique history and characteristics, particularly in this beautiful mountain town and working through the questions, fears and unknowns with my Buyers, it seemed like a good time to take a closer look at preserved wood in Canmore which are common in Cougar Creek, Peaks of Grassi - and now apparently sprinkled around Eagle Terrace. In recent years, preserved wood foundations have gotten a bit of a bad reputation but in the right environment with a little education and care of ownership, they don’t have to be a bad thing compared to their concrete counter part, especially in the right environment like Canmore with it’s dry climate.

A Brief History of Preserved Wood in Alberta

Preserved wood foundations, often referred to as pressure-treated wood foundations, were a common foundation type starting in the 1960’s spanning the late 90’s.  This construction technique involves using lumber that has been treated with chemicals to resist decay and insect damage. The process involves pressure-treating the wood with preservatives like chromated copper arsenate (CCA) or ammoniacal copper zinc arsenate (ACZA). This treatment makes the wood highly resistant to rot and pests, extending its lifespan significantly.

Positives of Preserved Wood Foundations

1. Durability

One of the key advantages of houses with preserved wood foundations is their durability. The preserved wood is well-suited to withstand the often harsh mountain climate, including heavy snowfall, freezing temperatures, and moisture. It resists decay and insect damage, which are common issues for traditional wood foundations.  They also have more flex than concrete which is prone to cracking as the ground settles or it goes through a few freeze-thaw cycles so it can withstand movement within a ‘normal’ range any new home experiences.

2. Low Maintenance

Preserved wood foundations typically require less maintenance than concrete foundations. They are resistant to decay and pests, reducing the need for frequent upkeep.  Concrete foundations are durable but may require periodic inspections for cracks and may be susceptible to moisture-related issues like cracking or efflorescence, necessitating maintenance and repairs.

3. Cost-Effective

While preserved wood foundations may have a slightly higher upfront cost compared to concrete or other materials, they can be cost-effective in the long run due to their extended lifespan and reduced maintenance requirements.

Negatives of Preserved Wood Foundations in Canmore

1. Vulnerability to Moisture

While preserved wood is resistant to moisture to some extent, it's not entirely impervious (much like concrete which is porous and also not waterproof, just resistant). In Canmore's dry climate, this might not be a significant concern, especially in areas that aren’t affected by the high water table or steep creek hazards. If the house is exposed to excessive moisture, such as flooding from nearby creeks, it could be problematic with costly  repairs or if it is caught early and addressed properly, it doesn’t have to be deal breaking in our dry climate but further due diligence is requited before making a decision on what to do, including getting a foundation specialist in.

2. Aging Preservative Treatments

Houses built in the 1990s with preserved wood foundations may have older preservative treatments like CCA, which have faced environmental and health concerns. Although the risk is generally considered low, some homeowners may prefer alternatives with newer, safer treatments.

3. Limited Load Capacity

Preserved wood foundations may have a more limited load-bearing capacity compared to concrete foundations. This limitation can affect your ability to undertake structural modifications or additions to the home in the future, potentially restricting your renovation options.  It is also why we don’t see it in large multi-unit buildings, they are most common in single family and duplexes but have been found on rare occasion in some 4-plexes locally.

Neighborhoods with Preserved Wood Foundations

In Canmore, preserved wood foundations were prevalent in neighborhoods like Cougar Creek, Peaks of Grassi, and in a handful of properties in Eagle Terrace and South Canmore. If you're considering a home in one of these neighborhoods, it's essential to assess the condition of the preserved wood foundation, as it has likely been exposed to the elements for several decades.

Before purchasing a home with a preserved wood foundation, it's advisable to:

  1. Inspect Thoroughly: Hire a qualified home inspector to assess the foundation's condition, looking for signs of decay, insect damage, or other issues.  If further investigation is needed, a foundation specialist should be called in. 

  2. Ask for Maintenance Records: If possible, request maintenance records from previous homeowners to ensure the foundation has been properly cared for.

  3. Consider Future Maintenance: Factor in potential future maintenance costs and whether you are comfortable with the long-term care required for this type of foundation.  The key here is proper water management with lot slope, landscaping & eavestroughs/downspouts.  If you have a preserved wood foundation in a secondary home where you are not there all the time, making sure the person you have checking your property (which is usually required for insurance purposes anyways), is paying extra attention to any water in the lowest level of your home.

In conclusion, houses with preserved wood foundations can be a viable option in Canmore's typically dry climate. They offer durability and lower maintenance requirements but may have limitations in terms of aesthetics and vulnerability to moisture. If you're considering such a property in neighborhoods like Cougar Creek, Peaks of Grassi, or Eagle Terrace, make sure to perform a thorough inspection and consider both the advantages and disadvantages before making your decision.  If you google Preserved woof foundations, much like when you WebMD your symptoms, you end up with a death sentence but that’s not always accurate.  Education and working with the right people who know or understand the problem at hand is key.

NOTE:  There is a history of incorrectly built preserved wood panels used in a number of homes in Peaks of Grassi which have resulted in significant foundation issues because of the supplier’s poor craftmanship.  A developer in the area hired a manufacturing company to supply these pre-fab panels that were meant to be built, shipped then used onsite to erect the foundation walls, instead of building everything from start to finish in place.  We are now finding out that the Supplier of these panels used pressure treated plywood sheeting to encase the wall studs but the wall studs & hardware inside of the plywood panels was not pressure treated and that’s a problem.  If these untreated studs get wet, that can be hugely problematic to the structural integrity of the home.  The use of pre-fab panels vs. traditional on-site construction was not the preferred or common method used when preserved wood foundations were being built other than in Peaks of Grassi so it is again very situational depending on the property as to what your risk tolerance needs to be when looking at a home with a preserved wood foundation.  Abalon Foundation Repairs in Calgary are a wealth of knowledge on the topic for Peaks of Grassi and other foundation issues in the Bow Valley.

There was one builder in the preserved wood era who used it in some South Canmore 4-plexes, particularly on 5th Street, with the higher water table in the Valley floor, this is a less ideal environment for preserved wood making it a different conversation in that location as well.

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