Insulation
Internal wall insulation and ISO-Therm systems
Internal wall insulation and ISO-Therm insulated boards for solid walls, warming cold surfaces to reduce condensation and mould.
Why diagnosis matters
Treat the cause, then repair the damage
Solid walls and hard-to-treat cavities stay cold, and cold surfaces attract condensation and mould. Internal wall insulation, including ISO-Therm insulated board systems, warms the internal face of the wall. We detail it carefully to avoid trapping moisture and finish it ready for decoration.
Technical review
Dan, Director / Surveyor
Last reviewed: July 2026. Advice is general until the property, access and visible evidence have been assessed.
Guarantee & aftercare
Written guarantee terms are matched to qualifying work, with inclusions, exclusions and aftercare explained before acceptance.
What we consider
Possible causes and lookalikes
Solid walls with no cavity to insulate
Cold bridging at reveals and junctions
Low surface temperatures raising humidity
Poor previous insulation detailing
Inspection method
A clear work sequence
Step 1
Assess the wall, moisture and room use
Step 2
Confirm any damp is resolved before insulating
Step 3
Fit insulated board systems with correct detailing
Step 4
Finish ready for skim and decoration
Scope boundaries
Honest about what the work does—and does not—cover
We install internal wall insulation and ISO-Therm insulated board systems, and reinstate the finish in-house. We resolve any underlying damp first and refer structural or specialist waterproofing design where it belongs elsewhere.
Common questions
About internal wall insulation and iso-therm systems
What is ISO-Therm?+
ISO-Therm refers to an internal insulated board system fixed to the inside of a wall to warm the internal surface. It is one of the internal insulation options we use for solid or cold walls.
Can I insulate a damp wall?+
No. Any underlying damp must be diagnosed and corrected first, otherwise insulation can trap moisture. We assess and resolve the cause before installing internal insulation.
Will internal insulation reduce room size?+
Internal systems add a modest thickness to the wall, so there is a small loss of floor area. We explain the build-up and finish before you commit.
Related services
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Next step
Claim your complimentary survey before choosing a treatment
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