Module 3: Insulation Installation Techniques 

3.1 Wall Insulation (Cavity, Solid, External & Internal)

A) Cavity Wall Insulation

• Description: Fills the gap between inner and outer brick/block leaves

• Installation Methods:

• Blown mineral wool or polystyrene beads (most common)

• Injection foam for irregular cavities

• Key Considerations:

• Requires professional installation with specialized equipment

• Must check for existing moisture problems first

• Not suitable for exposed or rain-prone locations

• Benefits:

• Minimal disruption to property

• Improves thermal efficiency by 30-40%

B) Solid Wall Insulation

• External Wall Insulation (EWI):

• Insulation boards fixed to exterior face

• Finished with render or cladding

• Requires planning permission in some areas

• Internal Wall Insulation (IWI):

• Rigid boards or stud wall with insulation

• Reduces internal room space

• More affordable than EWI but causes more disruption

• Comparative Analysis:

• EWI is 30% more effective but 50-70% more expensive

• IWI better for heritage properties with facade restrictions

3.2 Roof & Loft Insulation Methods

A) Cold Roof Insulation

• Standard Approach: Insulation laid between and over joists

• Materials: Mineral wool (300mm recommended), rigid boards

• Critical Details:

• Maintain 50mm ventilation gap at eaves

• Use breathable membrane if re-roofing

• Board over insulation for storage areas

B) Warm Roof Insulation

• Installation: Insulation above rafters (under roofing material)

• Advantages:

• Creates thermally efficient envelope

• Prevents condensation in roof structure

• Materials: PIR boards (120-150mm typical)

• Considerations:

• Requires adjustment of roof detailing

• More expensive but superior performance

C) Pitched Roof Insulation

• Between Rafters: Rigid boards cut to fit tightly

• Under Rafters: Insulated plasterboard

• Hybrid Approach: Combination for maximum efficiency

3.3 Floor Insulation (Suspended & Solid Floors)

A) Suspended Timber Floors

• Installation Methods:

• Insulation between joists (net-supported)

• Rigid boards fixed to underside

• Combination approach for best results

• Key Requirements:

• Maintain 25mm air gap below insulation

• Install vapor barrier on warm side

• Use moisture-resistant materials (PIR, phenolic foam)

B) Solid Concrete Floors

• Above Slab Installation:

• Rigid insulation (100-150mm) under screed

• DPM must be correctly positioned

• Below Slab Installation:

• Insulation beneath concrete slab

• Requires structural considerations

• Edge Insulation: Essential to prevent thermal bridging

3.4 Pipe & Duct Insulation

A) Pipe Insulation Standards

• Minimum Requirements:

• Heating pipes: 25mm thickness

• DHW pipes: 19mm thickness

• Refrigeration pipes: Specialized materials

• Materials:

• Flexible elastomeric foam (most common)

• Mineral wool for high-temperature applications

• Pre-formed foam sections for easy installation

B) Ductwork Insulation

• HVAC System Requirements:

• External insulation preferred

• Minimum 50mm for supply ducts

• Vapor barrier essential in humid environments

• Installation Tips:

• Seal all joints before insulating

• Support insulation properly to prevent sagging

• Use fire-rated materials where required

3.5 Air Sealing & Vapor Barriers

A) Air Tightness Strategies

• Critical Areas:

• Window/door reveals

• Service penetrations

• Loft hatches

• Intermediate floors

• Materials:

• Expanding foam for gaps >5mm

• Compressible tapes for joints

• Membranes for large areas

B) Vapor Control Layers

• Positioning Rules:

• Always on warm side of insulation

• Continuous with overlaps sealed

• Material Selection:

• Polyethylene sheets (basic)

• Intelligent membranes (variable permeability)

• Foil-backed boards (integrated solution)

• Installation Checks:

• Minimum 150mm overlaps

• Proper sealing around penetrations

• Compatibility with wall systems

Professional Best Practices

1. Always conduct pre-installation moisture surveys

2. Follow manufacturer's installation guidelines precisely

3. Use appropriate PPE for each material type

4. Verify U-values meet building regulations

5. Document installation for warranty purposes

Common Installation Errors to Avoid

• Compression of fibrous insulation

• Gaps between insulation boards

• Incorrect vapor barrier placement

• Inadequate fire-stopping details

• Poor attention to thermal bridging

This module provides the technical foundation for proper insulation installation across all building elements, emphasizing correct detailing to achieve optimal thermal performance and compliance with building standards