Continuous insulation

Continuous insulation is an insulation layer, typically rigid foam board, run over the outside face of the framing so it covers the whole wall plane in one uninterrupted blanket, without the thermal bridges that studs create through cavity batts. It is common in high-performance and passive-house walls.

The problem it solves is thermal bridging. When insulation sits only between the studs (cavity batts), the studs themselves are a path for heat to bypass the insulation, timber framing typically takes up around 15 to 20% of the wall area, and steel framing is far worse because steel conducts heat strongly. Those framing members short-circuit the batts, dropping the wall’s real-world performance below what the batt R-value alone suggests.

Continuous insulation goes over the framing, not between it, so the whole wall, studs included, is covered by an unbroken layer. The two are often combined: cavity batts between the studs plus a continuous board over the outside, which both lifts the total R-value and removes the bridging. It changes the wall build-up (the cladding fixes through or over the board, on battens), so the detailing, fixing length, and window flashing have to suit.

For a builder the practical points are that continuous insulation is one of the most effective ways to lift a wall’s actual thermal performance (and it is increasingly relevant as the NCC energy provisions tighten), but it needs the build-up worked out up front: how the cladding fixes back through the board to the frame, longer fasteners, batten thickness, and reworked window and door flashings so the weather line still works. Done as an afterthought it causes fixing and waterproofing headaches.

Also known as: Exterior insulation, over-frame insulation.

Category: Insulation / Thermal performance.

Related

• Rigid foam
• NCC energy efficiency

See also

• Sarking

References

• Rigid foam (Chalkline) (verified 2026-06-01)

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Last updated: 2026-06-01. Verified: 2026-06-01. Quarterly review for currency.