Attic Insulation Guide — Smiths Falls & Renfrew County

Attic Insulation Types Available in the Rideau Valley

Smiths Falls homeowners have three primary attic insulation options. Each has distinct advantages depending on your home's age, attic configuration, access, and budget. The right choice for a century home on Beckwith Street may differ from what works in a 1990s bungalow in a newer subdivision.

Blown-In Cellulose Insulation

Blown-in cellulose is the most popular attic insulation choice in Smiths Falls and across Renfrew County. Made from recycled paper products treated with fire retardant, cellulose is blown into the attic cavity to the desired depth using a hose from a truck-mounted blower. It provides excellent coverage around obstructions like wiring, plumbing stacks, and ceiling fixtures. Cellulose offers an R-value of approximately R-3.6 to R-3.8 per inch. To achieve Ontario's recommended R-60 in Smiths Falls, you need approximately 17 inches of settled cellulose. Costs range from $1.50 to $2.50 per square foot installed.

Blown-In Fibreglass Insulation

Blown-in fibreglass is an alternative to cellulose, offering R-2.2 to R-2.8 per inch. Because of its lower R-value per inch, achieving R-60 requires about 22 inches of depth — significantly more than cellulose. Fibreglass is non-combustible and does not settle as much as cellulose, but it costs more per square foot at $2.00 to $3.50. Some Smiths Falls homeowners prefer fibreglass for its moisture resistance in older attics with ventilation concerns.

Batt Insulation

Fibreglass batts are the most DIY-friendly option, available at hardware stores in Smiths Falls and Perth. R-30 batts (approximately 10 inches thick) can be layered to reach R-60. However, batts are difficult to install properly in attics with trusses, wiring, and obstructions — gaps reduce effective R-value significantly. Batt insulation material costs $0.60 to $1.00 per square foot, making it the cheapest material, but labour is extra if hiring a contractor.

R-Value Targets for Climate Zone 6 (Smiths Falls)

Smiths Falls is in Climate Zone 6 under the Ontario Building Code Supplementary Standard SB-12. This is eastern Ontario's coldest climate zone, reflecting the region's long heating season and extreme winter temperatures. The recommended and code-minimum R-values for attics in this zone are:

Many Smiths Falls homes from the pre-1990 era have attic insulation levels of R-12 to R-20. Upgrading to R-60 can reduce annual heating costs by 30–50%, representing a potential savings of $750 to $2,500 per year depending on home size and heating fuel.

Attic Insulation Cost Table

Note that these prices cover insulation material and basic installation only. Additional costs for air sealing, baffle installation, and existing insulation removal can add $500 to $2,000 to the total project cost.

Existing vs. New Construction Attic Insulation

Attic insulation requirements differ between existing homes and new construction in Smiths Falls. In new construction, the full attic space is accessible before drywall is installed, making insulation installation straightforward. The builder can install batts or plan for blown-in insulation with proper baffles and air sealing from the start.

For existing Smiths Falls homes, the approach depends on current insulation levels and attic access. If the attic has less than R-20, the most common upgrade is to add a top-up layer of blown-in cellulose over existing insulation. The Ontario Building Code allows top-ups if the existing insulation is dry, in good condition, and free of mould or pest contamination. If existing insulation is damaged, wet, or infested, it must be removed and disposed of before new insulation is installed — this adds $500 to $1,500 to the project for removal and disposal.

Smiths Falls homes with knob-and-tube wiring require special attention — insulation cannot be placed directly over knob-and-tube wiring as it may cause overheating. In these homes, the wiring must be evaluated by a licensed electrician before any attic insulation work proceeds. This is a common situation in pre-1950s homes in historic Smiths Falls neighbourhoods.

Air Sealing Before Insulating

Before any attic insulation is installed, air sealing of the attic floor is essential. Common air leakage points in Smiths Falls homes include:

• Penetrations around plumbing vents and electrical wiring
• Gaps around chimney and flue passages
• Recessed lighting fixtures (can lights) — these must be IC-rated and sealed
• Attic hatch openings — a major and often overlooked leak point
• Top plates of interior walls where drywall does not meet the ceiling
• Bathroom exhaust fan housings

Air sealing materials include acoustic sealant (caulking), expanding spray foam for larger gaps, and rigid foam board for attic hatches. A properly air-sealed attic floor reduces heat loss by an additional 15–25% on top of the insulation itself.

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