Insulated slab edge and slab-to-wall thermal break

Passive · New build only

Closes the second path a thermal bridge takes, from inside air to cold ground. Rigid insulation runs vertically at the slab edge and horizontally under the perimeter, with a break between slab and foundation wall, so heat does not run out of the floor through the slab edge into the soil. Cast in with the slab, so it belongs to the build.

One of 4 ways to meet Thermal bridging elimination. Build 2/4, Upkeep 1/4, Efficiency not rated. Cost, carbon and footprint below are rated against those 4, not in absolute terms.

Cost: Low
Upkeep: None
Skill to build: Intermediate
Lifespan: Matches the slab, being cast in with it and unreachable afterwards
Embodied carbon: Medium
Space / material use: Low
Output timing: None
Skill to repair: None

Inputs

none

Outputs

none

Ranking in its sub-function out of 4 alternatives

Every option in this sub-function, with the value on each axis and a note on what drives it (this solution highlighted):

Solution	Build skill	Upkeep burden	Efficiency
Continuous exterior insulation detailing	Basic	1	N/A
Strapped straw external insulation (ITE paille sanglee)	Intermediate	2	N/A
Insulated slab edge and slab-to-wall thermal break	Intermediate	0	N/A
Exterior slab-edge insulation (retrofit)	Intermediate	3	N/A

Build skill and upkeep burden are proxies (lower burden = simpler to maintain); the efficiency column is this sub-function’s ranking, 1 = best. “N/A” where an axis isn’t rated here.

Sources

Building America Solution Center, "Slab Edge Insulation" (PNNL / US DOE): heat is conducted out through the slab perimeter into the soil, and the slab-to-foundation-wall joint must be insulated or a significant thermal bridge remains

Tutorials

No build tutorial recorded yet.

What this page does not tell you

No sizing or quantities: how much a technique yields, and how much a household needs, both depend on the build and the people, so the catalogue compares options rather than dimensioning them. It carries no bill of materials and no build sequence, and it is written for an oceanic, clay-soil climate (Normandy, France). Regulatory notes are indicative and need confirming locally.