Wat is the R-value of a typical EIFS system used in Ottawa?

The R-value of an EIFS system in Ottawa depends primarily on the thickness of the insulation board used, and for our climate, you want to be strategic about choosing the right amount. EIFS is one of the few cladding systems where you can dial in your exact insulation level by simply specifying thicker foam — and in a city with 8,000+ heating degree days, more is almost always better.

EIFS R-Values by Insulation Thickness

The standard insulation material in EIFS is Type 1 expanded polystyrene (EPS), which provides approximately R-4 per inch. Here's what typical Ottawa installations deliver:

• 1.5" EPS: R-6 — minimum for cosmetic applications, rarely adequate as primary insulation in Ottawa
• 2" EPS: R-8 — common for retrofits where wall thickness is constrained
• 3" EPS: R-12 — popular choice for Ottawa residential projects balancing performance and cost
• 4" EPS: R-16 — excellent for new construction or deep energy retrofits
• 6" EPS: R-24 — high-performance builds targeting near-passive levels

Some Ottawa installers offer extruded polystyrene (XPS) at approximately R-5 per inch, or polyisocyanurate (polyiso) at R-6 to R-6.5 per inch. However, polyiso's R-value drops in cold temperatures — at -15°C (a normal Ottawa January night), polyiso can lose 20–25% of its rated R-value. EPS is more stable across Ottawa's temperature range, which is why most EIFS specialists here prefer it.

What the Ontario Building Code requires: For Part 9 residential buildings in Ottawa (Climate Zone 6), the OBC supplementary standard SB-12 prescribes effective wall R-values that typically work out to R-22 to R-27 for the complete wall assembly, depending on the compliance path chosen. EIFS with 3–4 inches of EPS, combined with standard cavity insulation, comfortably meets these requirements. The continuous nature of EIFS insulation — no thermal bridges at studs — means its effective R-value closely matches its nominal value, unlike cavity insulation which loses 15–25% of its rated value to framing thermal bridges.

Cost versus R-value in Ottawa:

• 2" EIFS system: $14–$18/sq ft installed
• 3" EIFS system: $16–$21/sq ft installed
• 4" EIFS system: $18–$24/sq ft installed

The incremental cost of going from 2" to 4" is only about $3–$6 per square foot — relatively modest for doubling your insulation value. Given Ottawa's long heating season and rising energy costs, the thicker option almost always delivers a better return over the life of the system. For most Ottawa homeowners, 3" of EPS (R-12) is the sweet spot — meaningful energy savings without excessive wall buildup or cost.

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Looking for experienced contractors? The Ottawa Construction Network connects Ottawa homeowners with qualified professionals:

• Justyn Rook Contracting
• RenoMotion Inc.
• The Granite shop
• Grunt Work 4 Grunts
• Somar Contracting Inc.

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