Insulation Basics: Materials and Methods

Insulation work keeps buildings comfortable and energy costs down. Understanding the materials and methods helps whether you're installing or specifying.

Types of Insulation

Common insulation materials:

• Mineral wool: Flexible batts, good acoustic properties
• PIR/PUR boards: Rigid, high performance, thin profiles
• EPS/XPS: Polystyrene boards for various applications
• Natural materials: Sheep's wool, wood fibre, recycled options
• Spray foam: Expanding foam for irregular spaces

Where to Insulate

Heat escapes through:

• Roof/loft: Often the biggest heat loss
• Walls: Cavity or solid wall insulation
• Floor: Especially over unheated spaces
• Windows and doors: Often replaced rather than insulated

U-Values

U-values measure thermal performance:

• Lower numbers = better insulation
• Building regulations set minimum standards
• New build requirements differ from refurbishment
• Check current Part L requirements

Loft Insulation

The easiest upgrade:

• Current standard: 270mm mineral wool
• Lay between joists first, then across
• Don't compress - thickness matters
• Maintain ventilation at eaves
• Insulate loft hatch too

Cavity Wall Insulation

For properties with cavity walls:

• Injected through small holes
• Various materials (beads, foam, fibre)
• Must be done by approved installers
• Check wall condition first

Solid Wall Insulation

More complex but high impact:

• External: Thick layer outside, needs render finish
• Internal: Reduces room size, affects fixtures
• Both need careful detailing
• Significant cost but significant savings

Vapour Control

Critical to prevent condensation:

• Vapour barrier on warm side
• Breathable membrane on cold side
• Proper sealing at all edges
• Failures cause damp and damage

Safety Considerations

• Mineral wool irritates skin - wear protection
• Respiratory protection when cutting
• Work in ventilated spaces
• Dispose of waste properly