Wall insulation in 2026: ITE or ITI, and which grants?

Why insulate walls first

Walls account for up to 25% of heat loss in a poorly insulated house. Insulating them clearly improves comfort and the DPE — often the condition for a real performance jump.

ITE or ITI?

• External insulation (ITE): the most effective (no thermal bridging), with no loss of living space, but more expensive and subject to planning permission.
• Internal insulation (ITI): cheaper and simpler, but slightly reduces floor area and leaves thermal bridges.

The required performance

To be grant-eligible, the quote must state a compliant thermal resistance R:

• Walls (ITE or ITI): R ≥ 3.7 m².K/W

The contractor must be RGE-certified, and the grant application filed before works start.

Watch the 2026 calendar

From 1 September 2026, wall insulation is no longer fundable as a standalone gesture: it must be part of a whole-home renovation. If you want a single gesture, file your application before the deadline.

The right method

1. Estimate your grants and check your income band.
2. Ask for an RGE quote stating the R value.
3. File your application before signing the quote.

Indicative information — check the thresholds in force with ANAH.