Glossary · Insulation & windows

Continuous insulation (ci)

Also called: exterior insulation · exterior rigid insulation · insulated sheathing · insulative sheathing · outsulation

A layer of insulation running unbroken over the framing, usually rigid boards on the outside of walls, to stop heat escaping through studs.

What it means

Because studs and other framing conduct heat (see thermal bridging), insulation placed only between studs leaves gaps in protection. Continuous insulation, commonly rigid foam or other rigid boards, covers the framing too. It also keeps the wall sheathing warmer, which lowers condensation risk.

Why it matters in an audit

It's often the best way to raise wall performance during a re-siding job, because the outside of the wall is already open.

Typical numbers

Reference values with their sources. Your energy advisor’s report gives the figure for your own house.

What	Value	Source
NRCan (exterior retrofits)	Often possible to add R-15 to R-20 rather than R-4 to R-10; keep any air gap behind it to 10 mm or less (it cuts the insulation's effect about 5%)	natural-resources.canada.ca ↗
Rigid foam R per inch (DOE)	R-3.2 to R-6.5, depending on type	bsesc.energy.gov ↗

Sources

Learn more here

Related terms

Thermal bridging Heat taking a shortcut through materials that insulate poorly, like wood studs, steel or concrete, running from the warm side to the cold side.
Rigid foam (EPS, XPS, polyiso) Stiff insulation boards made of foam plastic, used on foundations, under slabs and as a continuous layer over walls and roofs.
Rainscreen A small air gap behind siding or brick that lets rainwater that gets past the cladding drain away and lets the wall dry.
R-value How well a material resists heat flow; higher is better, and insulation is rated with it, such as R-20 for walls or R-50 for attics.
Condensation Water that forms when humid air touches a surface colder than its dew point, on windows, cold pipes or hidden inside walls and attics.

← Every term, A to Z