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.
Complimentary survey
Book Your Complimentary Survey
Over 35 years of independent expertise. Written findings included. No sales pressure. No obligation.
Book your complimentary surveyTechnical 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.
Complimentary specialist survey
Your Complimentary Specialist Survey
Backed by over 35 years of independent damp and timber expertise.
We believe in diagnosis before treatment. That's why we offer every homeowner and property manager in Dorset, Hampshire and Wiltshire a complimentary specialist survey — carried out by an experienced specialist, not a salesperson.
Over 400 combined reviews across Google and Checkatrade. Over 35 years protecting Dorset homes.
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.
Is the specialist survey really free?+
Yes — completely. We offer every homeowner and property manager across Dorset, Hampshire and Wiltshire a complimentary specialist survey at no charge. This includes an on-site inspection, written findings, a clear scope of any recommended work, and an honest referral if the problem falls outside what we do. You pay nothing for the survey. You only pay if you commission the remedial work, and you are under no obligation to do so. The reason we do this is straightforward: we believe in diagnosing the problem before recommending a treatment. A proper inspection takes time, and we'd rather invest that time up front than quote a solution before we've understood the cause.
Not sure if this is your problem?
That's exactly what the survey is for. Book your complimentary specialist survey and one of our experienced team will identify the cause on-site, consider the alternatives, and give you written findings — at no charge and with no obligation.
Related services
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Recent work
Photographed on our own projects
A selection of real jobs from this service, photographed on site across Dorset, Hampshire and Wiltshire.
Reviewed by local homeowners
Trusted across Dorset, Hampshire and Wiltshire
Independent feedback from customers on Google and Checkatrade — alongside over 35 years of damp proofing and plastering experience.
Next step
Claim your complimentary survey before choosing a treatment
Tell us what you can see, when it changes and where the property is. Photographs can help us triage the next step.