Vented Attic Roof Assemblies
how soffit intake, exhaust vents, baffles, air sealing, and insulation depth work as one roof system.
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Roof Insulation System Guides
Roof assembly guides for vented attics, cathedral ceilings, low-slope roofs, bonus rooms, kneewalls, condensation control, attic access, and renovation planning.
Cathedral Ceiling Insulation
roof insulation choices where there is little or no open attic and ventilation space must be protected.
Low-Slope Roof Insulation
thermal review for flat and low-slope roofs on Canadian commercial and residential properties.
Bonus Room Over Garage Insulation
roof, floor, kneewall, and air leakage details that make rooms above garages uncomfortable.
Kneewall And Sloped Roof Insulation
side-attic and sloped-ceiling details common in developed upper floors and older rooflines.
Roof Deck Condensation Control
why frost, staining, and wet sheathing usually point to air leakage and ventilation problems.
Attic Hatch And Access Insulation
small access details that can create outsized heat loss, drafts, and condensation paths.
Roof Insulation For Renovations
planning insulation before roofing, solar, mechanical, ceiling, or upper-floor renovation work.
Calgary headquarters service
Build the roof insulation scope around the roof, not a generic square-foot price.
Good attic insulation planning starts with roof shape, ventilation paths, ceiling penetrations, access, material condition, and the actual comfort complaint. The right scope may be a top-up, air sealing, baffles, removal, or a staged plan with roofing work.
Assessment priorities
- Confirm insulation depth and coverage by roof zone.
- Find air leakage before adding loose-fill insulation.
- Protect soffit intake with baffles and clear ventilation paths.
- Document moisture, frost, staining, odour, and access constraints.
Roof assembly · Reviewed 15 July 2026
Expert review: Roof Insulation System Guides
What our crews see in the field
- Roof Insulation System Guides only performs when the air-control layer, vapour retarder, insulation layer and ventilation path are designed as one system.
- Vented attics need ≥1:300 net-free ventilation area, split roughly 50/50 intake-to-exhaust, with baffles maintaining ≥63 mm (2.5″) clear channel at every rafter bay.
- Cathedral and low-slope assemblies without a vent channel must meet NBC 9.25.5.2 exterior-to-total insulation ratios or use a Class II vapour retarder + fully-adhered air barrier.
- Sheathing moisture above 19% MC (measured with a pin meter) in February is the failure threshold — above that, we recommend removing insulation to inspect for rot before topping up.
How we source this content
Every page on roofinsulation.ca is written by a working estimator, reviewed by a professional engineer, and cross-checked against the National Building Code of Canada, NRCan EnerGuide procedures, ASHRAE Fundamentals and CMHC research reports. Job-cost figures are drawn from our own installed-project database (n = 2,000+ Canadian attics, 2018–2026) and refreshed each quarter.
Primary references cited on this page
- National Building Code of Canada 2020, Part 9.36 – Energy Efficiency
- NRCan – EnerGuide Rating System v.15 Technical Procedures
- Canada Greener Homes Grant – Eligible Retrofits
- Building Science Corporation – BSD-149: Unvented Roof Assemblies
- ASHRAE Fundamentals 2021 – Ch. 25 Heat, Air, and Moisture Control
- CMHC – About Your Attic Ventilation
- City of Calgary – Building Permits & Insulation Upgrades
Disclaimer: Information on this page is general Canadian building-science guidance and does not replace an on-site inspection by a qualified contractor, energy advisor or professional engineer. R-value targets, rebate amounts and code references are current as of 2026-07-15 and may change; verify with your local building department and NRCan before making a purchase decision.