How does a blower door test result compare before and after adding rigid foam continuous insulation to an older Moncton home exterior?

A blower door test on an older Moncton home will typically show a dramatic improvement after adding continuous rigid foam exterior insulation — often reducing air leakage by 30-50% even when the rigid foam installation is the only upgrade performed.

Most Moncton homes built in the 1960s-1980s test at 8-15 ACH50 (air changes per hour at 50 pascals) before any upgrades. This means the entire volume of air in the house leaks out and is replaced 8-15 times per hour under standard test pressure — far above the current NB Building Code target of 3.5 ACH50 for new construction. After adding 2-3 inches of continuous rigid foam (typically XPS or polyiso) over the existing sheathing with proper sealing, the same home often tests at 5-9 ACH50 — a substantial improvement that translates to measurable comfort and energy savings.

The air sealing improvement comes not from the rigid foam itself, but from the installation process that addresses major thermal bridges and air leakage points. When contractors install continuous exterior insulation, they must remove and reinstall all the trim around windows and doors, which provides an opportunity to properly air seal these major leakage points with high-quality sealants and weatherstripping. The rigid foam also covers the rim joist area (where the floor framing meets the foundation wall) — one of the largest sources of air leakage in older Maritime homes. Additionally, the foam covers the wall sheathing joints and nail holes that have been leaking air for decades.

The building science behind the improvement is significant in Moncton's climate. Continuous exterior insulation eliminates thermal bridging through the wall studs, which in a standard 2x6 wall with R-20 batts reduces the effective whole-wall R-value from the theoretical R-20 down to about R-16 due to heat loss through the wood framing. Adding R-10 continuous foam brings the true whole-wall performance up to R-26+ while simultaneously reducing air leakage. This combination addresses both conductive heat loss (through solid materials) and convective heat loss (through air movement) — the two primary mechanisms of heat loss in NB's cold winters.

Typical before/after blower door results for a comprehensive exterior insulation project on a 1,200 square foot Moncton bungalow might look like:

• Before: 12 ACH50 (roughly 2,400 cubic feet per minute of air leakage at test pressure)


• After: 6 ACH50 (roughly 1,200 cubic feet per minute) — a 50% reduction in air leakage

This improvement typically reduces heating costs by 20-35% in the first year, with the air sealing component responsible for about half of that savings. The homeowner notices immediate comfort improvements — fewer drafts, more even temperatures between rooms, and less noise from wind and traffic due to the improved building envelope.

Important considerations for Moncton homes: The Maritime climate brings high humidity, and dramatically reducing air leakage can sometimes create moisture management challenges if the mechanical ventilation is inadequate. Homes that achieve very low ACH50 results (below 5) should have their ventilation systems evaluated to ensure adequate fresh air exchange. Many older Moncton homes rely on natural air leakage for ventilation, so when that leakage is reduced, controlled mechanical ventilation (HRV/ERV systems or upgraded bathroom fans) becomes more important.

For rebate eligibility, both NB Power's Total Home Energy Savings Program and the federal Greener Homes Grant require professional EnerGuide evaluations that include blower door testing before and after the work. The improvement in air tightness is a major factor in the energy savings calculations that determine rebate amounts — potentially worth $2,000-$5,000 in combined incentives for a comprehensive exterior insulation project.

When to hire a professional: Continuous exterior insulation requires removing and reinstalling siding, proper flashing details around windows and doors, and coordination with other trades. This is definitely professional-grade work that requires building science knowledge, specialized tools, and experience with moisture management in Maritime climates.

Need help finding a professional insulation contractor experienced with continuous exterior insulation? New Brunswick Insulation can match you with qualified contractors in the Moncton area for free estimates.