Attic Insulation Guide — Renfrew County, Ontario

Attic Insulation in the Ottawa Valley Climate

The attic is the single most important area to insulate in any Renfrew County home. Heat rises, and in winter — when outdoor temperatures in Pembroke and the surrounding area regularly plunge to −25°C or colder — a poorly insulated attic is the primary route for heat loss. In a typical home, 25% to 35% of total heat loss occurs through the attic.

Many homes in Renfrew County were built 40 to 80 years ago, when insulation standards were dramatically lower. A 1950s bungalow in Pembroke may have only 4 to 6 inches of loose-fill insulation in the attic — providing perhaps R-12 to R-20. Under current Ontario Building Code requirements (SB-12), the minimum for Climate Zone 6 is R-50, with R-60 recommended. That is roughly three to four times the insulation in most older homes.

The good news: attic insulation is one of the most cost-effective energy upgrades available. The improvement in energy efficiency from upgrading an R-12 attic to R-60 is dramatic, and the payback period — particularly with current energy costs in Ontario — is typically 2 to 5 years for an average home.

Types of Attic Insulation

Blown-In Cellulose

Blown-in cellulose is the most common attic insulation choice in Renfrew County. Made from recycled paper treated with fire retardants (boric acid), cellulose is blown into the attic using a hose and machine. It flows around obstructions — wiring, plumbing vents, truss members — and settles into a uniform blanket with few gaps. Cellulose also has good air-sealing properties due to its density, which is a meaningful advantage in cold climates.

Cellulose typically achieves approximately R-3.2 to R-3.7 per inch. To reach R-60, you would need roughly 16 to 19 inches of settled depth, depending on the product and installation quality.

Blown-In Fibreglass

Blown-in fibreglass is another loose-fill option, made from spun glass fibres. It is lighter than cellulose and achieves approximately R-2.2 to R-2.5 per inch, meaning more depth is required for the same R-value. Blown fibreglass does not settle as much as cellulose, but it also does not provide the same air-sealing benefit. It is unaffected by moisture (mould-resistant) and is non-combustible.

Fibreglass Batts

Fibreglass batts are pre-cut sheets of insulation that fit between ceiling joists. They are common in new construction and in simple, open attic spaces with regular joist spacing. Batts are less expensive than blown-in options on a per-square-foot basis and can be installed by a homeowner. However, in existing attics with complex layouts, multiple obstructions, and irregular joist spacing, batts leave more gaps and are harder to install properly than blown-in materials.

R-Value Targets for Ottawa Valley Climate Zone (Zone 6)

Renfrew County falls under Ontario Climate Zone 6 — the coldest zone in the province. The Ontario Building Code's supplementary standard SB-12 specifies the following minimum R-values for attic insulation:

To put these numbers in perspective: R-50 requires roughly 14–16 inches of blown-in cellulose or 20–22 inches of blown-in fibreglass. Many Pembroke-area attics currently have 4–8 inches of old material, meaning the homeowner would need to add 6–12 inches depending on existing depth and material type.

Ventilation Baffles and Proper Attic Ventilation

Adding insulation to an attic is not simply a matter of piling material higher. Proper attic ventilation is essential, particularly in Renfrew County's heavy-snow climate. The insulation must not block the flow of air from soffit vents (at the eaves) to ridge vents or gable vents. This is achieved by installing ventilation baffles (also called rafter vents or insulation chutes) at the eaves before adding insulation.

Baffles ensure that cold air can enter through the soffit vents and travel upward along the underside of the roof deck to exit at the ridge. This airflow keeps the roof deck cold (preventing ice dams), removes moisture that migrates into the attic, and extends the life of the roofing materials. Baffles are inexpensive ($2–$5 each) and should be installed between every rafter bay at the eaves before insulation goes in.

Air Sealing Before Insulating

Air sealing the attic floor before adding insulation is critical. Without sealing the gaps and penetrations that allow warm, humid indoor air to escape into the attic, additional insulation alone will not solve ice dam problems or achieve expected energy savings. Common attic air leaks in Renfrew County homes include:

• Plumbing vent stacks passing through the attic floor
• Electrical wiring and junction box penetrations
• Recessed (can) lighting fixtures — especially older non-IC-rated models
• Attic access hatches that are unsealed and uninsulated
• Chimney and flue chase penetrations
• Top plates of interior walls (warm air can rise through stud bays)
• Bathroom and kitchen exhaust fan housings

These should be sealed with caulk, spray foam sealant, or weatherstripping before new insulation is added. Many contractors include air sealing as part of a professional attic insulation upgrade. If you are hiring a contractor, confirm that air sealing is included in the scope of work.

Cost Estimates for Attic Insulation in Renfrew County

The following table provides typical cost ranges for attic insulation in the Pembroke and Renfrew County area. Prices are estimates only and vary based on access, existing insulation condition, and R-value target.

Costs assume standard attic access and typical obstruction levels. Attics with very low roof pitch, extremely limited access (crawl-only space), or requiring extensive air sealing may add 15–30% to the total.

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