Attic Insulation in Peterborough and Kawartha Lakes
Just Spray It provides attic insulation and other spray foam insulation services for homeowners, builders, and commercial properties.
Unvented Roof Insulation
An unvented roof assembly offers a more controlled approach to roof performance by installing insulation directly against the roof deck. This creates a tighter assembly, reduces air leakage, improves thermal control, and supports a more consistent building envelope.
Here’s why that matters.
When insulation is placed directly at the roof deck, it helps reduce heat transfer between the interior and exterior of the building. That improves energy efficiency, supports more stable interior conditions, and allows the roof system to perform as part of a complete, intentional envelope strategy.
Spray foam is often used in unvented roof assemblies because it solves two problems at once: insulation and air sealing. Applied correctly, it creates a continuous barrier that limits heat movement and reduces uncontrolled air leakage. That level of continuity is critical. In high-performance assemblies, gaps are not details. They are liabilities.
Unvented roof assemblies have been widely studied for their ability to improve thermal performance, reduce heating and cooling demand, and support the long-term durability of the roof system when compared to traditional ventilated assemblies.
That being said, this is not a one-size-fits-all solution. Moisture management still matters. Indoor air quality still matters. The rest of the building still has to be considered. An unvented roof assembly performs best when it is designed with the full project in mind: climate, materials, installation quality, mechanical systems, and the specific demands of the space.
The takeaway is simple: unvented roof insulation can be a strong solution when it is planned properly, detailed correctly, and installed with discipline. It is not just about eliminating vents. It is about creating a roof assembly that performs with intention.
Cellulose Insulation & Poly Plastic
In roof assemblies, cellulose blow-in insulation and poly vapour barriers are very common choices for insulation. They are cost effective and straightforward to install. They can also support energy performance when used in the right application.
But common does not always mean best.
Cellulose can settle over time, which can reduce its thermal performance. Poly vapour barriers can tear/puncture, or fail when detailing is not handled properly. In assemblies where long-term performance, durability, or tighter air control is the priority, cellulose and poly vapour may not be the strongest solution.
Spray foam insulation for example, can offer improved energy efficiency, stronger air sealing, and more lasting performance in certain roofing applications. The right choice depends on the project’s requirements, budget, assembly conditions, and performance goals.
A roof assembly should not be built around habit. It should be built around what the project actually needs.
Hybrid Insulation Systems
Hybrid insulation systems that incorporate spray foam can deliver measurable performance without overcomplicating the assembly or the budget.
The value is in the assembly.
Spray foam can combine insulation, air sealing, and moisture control in a single application. That means fewer layers, fewer weak points and less reliance on a separate vapour barrier. In roof assemblies, this can greatly improve energy performance by reducing heat loss and limiting air infiltration.
It also brings durability into the conversation. Unlike poly vapour barriers, spray foam is not as vulnerable to tearing or puncturing during installation or over time. When detailed correctly, it can support a stronger, more reliable ceiling assembly.
The goal is not to use the most expensive system. It is to use the system that performs where it matters.
For projects that require better insulation, tighter moisture control, and long-term assembly performance, a hybrid spray foam system can be a practical, high-performing choice without unnecessary cost. Visit our blog for more information.
Attic Insulation FAQs
The best attic insulation often depends on your roof design and budget. It will also depend on existing insulation and moisture conditions. For many homes in Peterborough and the Kawarthas, spray foam insulation or a hybrid insulation system can be a solid option because it helps reduce heat loss, air leakage and moisture movement.
Yes. Spray foam insulation is often a good choice for attics because it can provide insulation and air sealing in one application. This helps reduce heat transfer and air leaks.
The amount of insulation you will need for your attic will depend on the project. Visit our Budget Calculator page for a rough estimate.
An unvented roof assembly offers a more controlled approach to roof performance by installing insulation directly against the roof deck. This creates a tighter assembly, reduces air leakage, improves thermal control, and supports a more consistent building envelope.
Although cellulose is common for attic applications, spray foam insulation is the stronger performance choice. Cellulose can settle over time, which reduces thermal performance. Spray foam insulation reduces heat loss, limits air movement and improves the overall performance of the attic.
Yes, we also recommend using spray foam insulation for basements. Please check out our basement page or request a quote here.