Step-By-Step Guide

Internal wall insulation involves adding a carefully selected insulated lining to the inside of external walls.
A safe, effective installation requires proper assessment, moisture awareness, correct system choice, and a controlled installation process.
This guide explains each step clearly so homeowners know what to expect.

Before any work begins, we assess the walls and room conditions in detail.This includes:

• Thermal imaging to identify cold spots, thermal bridges and cold junctions
• Surface temperature readings
• Relative humidity checks
• Identifying where condensation forms
• Discussing moisture patterns with the customer (drying habits, heating patterns, showers, cooking etc.)
• Reviewing furniture placement (large furniture against cold walls can create mould-prone areas)
• Checking ventilation and airflow
• Inspecting plaster condition and wall type
• Reviewing bay windows, reveals and chimney breasts

Short description:
This step ensures we fully understand how the wall behaves so the correct insulation system can be chosen safely.

Once the assessment is complete, the room and wall are prepared for installation.

This includes:

• Covering furniture, flooring, carpets and belongings
• Protecting adjacent surfaces and keeping dust contained
• Removing skirting boards, window trims and boxing-in where needed
• Cleaning the wall and removing loose or hollow plaster
• Checking window junctions, corners and edges
• Ensuring the surface is suitable for the chosen insulation system

Short description:
Preparation creates a clean, safe working environment and ensures the wall is ready for insulation.

Internal wall insulation is not a single method — different systems require different installation techniques.
Depending on the assessment, the chosen system may include:

• Cork insulation
• Mineral wool
• PIR systems
• TIWI systems

During installation we:

• Use the correct fixing method for the system (PU adhesive, mechanical fixings, battens/studs, or combined systems)
• Follow the specific guidance for each material type
• Ensure the insulation layer is as continuous as possible
• Pay special attention to corners, reveals, chimney breasts, bay windows and junctions
• Avoid gaps that could create cold spots

Short description:
Each insulation system has its own method. We install it using the correct approach to match the wall, moisture behaviour and chosen materials.

Step 4 — Sealing Joints and Improving Surface Performance

Once the insulation system is in place, all necessary junctions and connections are treated according to system requirements.

This may include:

• Filling or taping joints
• Treating reveals and corners
• Ensuring airtightness where required
• Reducing cold bridging at sensitive locations

Short description:
Detailing the edges and joints helps improve surface temperature and reduce condensation risk.

Step 5 — Applying the Internal Finish

The final internal finish depends on the insulation system used.
It may include:

• A skim plaster finish
• Breathable mineral or lime plaster for breathable systems
• Plasterboard finish where the system requires it
• Reinstalling skirting boards, trims and other interior elements

Once complete, the wall is ready for painting or decorating.

Short description:
A clean, smooth finish completes the insulated lining and prepares the wall for decoration.

Step 6 — Final Thermal Inspection, Aftercare & Ventilation Guidance

After the installation is complete, we carry out a final visual and Thermal Imaging check to ensure the insulated wall is performing as expected.

Because internal wall insulation must work together with good moisture management, we also discuss:

• Everyday ventilation habits
• How heating patterns affect condensation
• The importance of maintaining airflow behind furniture
• Whether additional ventilation may be beneficial
• How to keep the insulated wall dry and stable long term

Short description:
A final thermal check confirms the installation has been carried out correctly, and clear ventilation guidance supports long-term performance.

A safe, effective IWI installation requires:

• Proper moisture assessment
• Correct system selection
• Clean preparation
• Accurate installation using the right method
• Careful sealing and finishing
• Post-install thermal checks
• Ventilation awareness

Each step supports the next, creating a warm, stable, moisture-aware internal surface.