When it comes to improving comfort and reducing energy bills, insulating older homes seems straightforward. But insulating an old house is rarely simple.
Unlike newer builds designed for modern energy performance, an old house often lacks proper wall insulation, attic insulation, and air sealing. Many homes built decades ago in Manitoba were constructed before today’s building code standards and before energy efficiency became a priority. That means insulating an old house requires more than just adding insulation; it requires understanding how the entire home performs as a system.
In Winnipeg’s cold climate, where long winters and extreme temperature fluctuations are normal, the challenges of insulating older homes become even more complex.
Understanding the Construction of an Old House
Every insulation project in an old house starts with understanding how it was originally built.
Older homes across Manitoba often feature:
- Solid plaster walls
- Minimal wall cavities
- Little to no exterior wall insulation
- Limited or non-existent vapor barrier systems
- Low levels of attic insulation
Many exterior walls were built with little consideration for modern R value targets. Instead of layered wall assemblies with continuous insulation, older exterior walls often rely solely on stud cavities; which increases thermal bridging through wood framing.
When insulating an old house, these construction differences matter. Modern insulation materials must work around structural constraints without trapping moisture inside walls or damaging plaster finishes.
Wall Insulation Challenges in Older Homes
Upgrading wall insulation in an old house is one of the most complicated parts of the retrofit process.
Many older homes contain:
- Empty wall cavities
- Settled loose fill insulation
- Deteriorated batt insulation
- Outdated fiberglass batts
Adding wall insulation requires careful evaluation of:
- Existing insulation
- Moisture management
- Electrical wiring in stud cavities
- Whether a vapor barrier exists
Dense-pack cellulose can sometimes be injected into wall cavities. In other cases, rigid foam boards or exterior wall insulation may be installed during siding replacement to reduce thermal bridging.
Reducing thermal bridging is especially important in cold climates like Winnipeg. Wood studs conduct heat, which lowers the effective R value of exterior walls. Exterior rigid insulation helps create a continuous thermal layer, improving overall energy performance.
Attic Insulation: A High-Impact Upgrade
In many older homes, attic insulation levels are far below modern standards.
Current Manitoba guidelines commonly target attic insulation levels around R-50. Many old houses have attic insulation levels closer to R-12 to R-20; or inconsistent coverage due to settling.
However, adding insulation alone does not solve every issue.
Before adding insulation, professionals should:
- Seal air leaks around plumbing stacks, electrical penetrations, and exhaust fans
- Improve the vapor barrier where possible
- Maintain ventilation channels
- Ensure proper airflow above insulation
Without proper air sealing, warm air from the home rises into the attic, condenses in cold weather, and can cause mold growth or moisture issues.
Proper attic insulation combined with air sealing significantly reduces heat loss and improves energy efficiency.
Crawl Space and Basement Insulation
Another overlooked area when insulating older homes is the crawl space or basement walls.
Cold floors in an old house are often caused by:
- Uninsulated floor joists
- Air leaks at rim joists
- Uninsulated crawl space walls
Spray foam insulation is commonly used in crawl space and basement applications because it acts as both insulation and an air barrier. It also helps control moisture in damp basement environments.
Batt insulation and mineral wool can also be used in floor joists, but must be protected from moisture to prevent performance loss.
Insulating a crawl space properly improves indoor air quality, comfort, and overall energy performance.
Moisture Management and Vapor Barrier Concerns
One of the biggest risks when insulating an old house is trapping moisture inside walls.
Older homes often lack a proper vapor barrier or weather barrier. If insulation is added without considering airflow and drying potential, excess humidity can become trapped within insulation layers.
This can lead to:
- Mold growth
- Wood rot
- Structural damage
- Reduced insulation performance
Moisture management is especially critical in cold climates, where warm air leaking into cold wall cavities condenses quickly.
A well-designed insulation project considers airflow, drainage plane design, and proper vapor barrier placement to prevent moisture issues.
Choosing the Right Insulation Materials
There is no one-size-fits-all solution when insulating older homes.
Common insulation materials used in retrofits include:
- Batt insulation (fiberglass batts or mineral wool)
- Dense-pack cellulose
- Rigid foam boards
- Spray foam insulation
- Loose fill insulation
Each insulation material offers different R value performance and moisture resistance.
Rigid insulation and exterior wall insulation help reduce thermal bridging. Mineral wool provides moisture resistance and fire protection. Fiberglass batts are economical but must be installed carefully to avoid gaps.
The right insulation materials depend on the structure of the old house, budget, and long-term goals for energy efficiency.
Why Insulating an Old House Requires Planning
An insulation project in an old house must account for:
- Existing insulation
- Air leaks
- Structural damage
- Vapor barrier placement
- Electrical wiring
- Stud cavity depth
- Drainage plane function
Improper installation can create new problems; especially when adding insulation without understanding airflow and moisture movement.
Professional guidance ensures proper installation method selection and reduces the risk of mold growth or structural damage.
Comfort, Energy Efficiency, and Long-Term Value
Insulating older homes improves:
- Comfort and energy efficiency
- Indoor air quality
- Reduced energy bills
- Lower energy costs
- Improved R value performance
While savings vary by home, properly insulating an old house often results in meaningful reductions in heating demand; particularly in Winnipeg’s long heating season.
The key is balancing:
- Proper insulation
- Air sealing
- Moisture control
- Ventilation
When done correctly, insulating an old house transforms it from drafty and inefficient to comfortable and energy efficient.
FAQ
Q: Can you add wall insulation to an old house without removing drywall?
Often, yes. If wall cavities are empty, dense-pack cellulose can be installed through small access holes from the interior or exterior. Before adding wall insulation, it’s important to assess existing insulation, electrical wiring, moisture management, and vapor barrier conditions to prevent future issues.
Q: What attic insulation level is recommended in Manitoba?
In Manitoba’s climate, attic insulation is commonly upgraded to around R-50. Many older homes fall well below this level. Before adding insulation, air leaks and ventilation must be addressed to prevent condensation and moisture problems.
Q: Why are the floors cold in my old house?
Cold floors are usually caused by poor wall insulation, air leaks at rim joists, or an under-insulated crawl space. Upgrading crawl space insulation, adding batt insulation, mineral wool, or spray foam can significantly reduce heat loss and improve comfort.
Q: What insulation materials work best for insulating an old house?
Common insulation materials include batt insulation (fiberglass batts or mineral wool), dense-pack cellulose, rigid foam boards, and spray foam insulation. In some cases, exterior wall insulation is added during siding replacement to help reduce thermal bridging and improve overall R value performance.
Q: Can adding insulation cause mold growth?
It can if moisture and airflow aren’t addressed. When insulating an old house, air sealing, proper vapor barrier placement, and moisture management must be considered to avoid trapping humidity inside insulation layers.
Q: Is exterior wall insulation worth it?
Yes, especially during siding replacement. Exterior rigid insulation helps reduce thermal bridging and improves energy efficiency by creating a continuous thermal layer over exterior walls.
Q: Will insulating an old house lower energy bills?
Results vary, but many older homes see meaningful improvements in comfort and reduced energy costs when attic insulation, wall insulation, and crawl space upgrades are completed together.
Final Thoughts
Insulating older homes is more complicated than many homeowners expect.
Limited wall cavities, outdated insulation materials, thermal bridging, moisture management concerns, and crawl space conditions all influence how an insulation project should be approached.
With thoughtful planning, proper air sealing, and the right insulation materials, even a century-old house can achieve modern energy performance without sacrificing its character.
If you’re considering insulating an old house in Manitoba, a professional assessment is the first step toward a safer, more energy efficient home.