Insulating a Loft Conversion: What You Need to Know

Catherine Allen
May 17
2 min read

One of the most critical components of a successful loft conversion is insulation. It not only keeps your space warm in winter and cool in summer but also helps with soundproofing and energy efficiency. At The Loft Build Company insulating a loft conversion is part of our standard high-spec process - no shortcuts, no compromises.

With Emmet and the team’s extensive experience in loft builds across London and Surrey we make sure every project is properly insulated, fully compliant with building regulations and tailored to our clients’ needs.

Why Insulation Matters

Proper insulation ensures:

A comfortable temperature year-round
Lower energy bills
Reduced carbon footprint
Compliance with UK Building Regulations (Part L)
Improved soundproofing between floors

Skipping or underestimating insulation can lead to condensation, poor thermal performance and unhappy homeowners. That’s why we prioritise it from the design phase onward.

Our Standard Loft Insulation Approach

At The Loft Build Company our standard insulation package includes:

Rigid foam insulation (e.g. Kingspan or Celotex) between and over rafters for excellent thermal performance without sacrificing headroom
High-density mineral wool between floors for sound insulation and fire protection
Insulated plasterboard for external walls and ceilings, providing extra thermal resistance
Air gaps and breathable membranes to allow for ventilation while preventing moisture build-up

We also install mains-powered extractor fans in any bathrooms to help manage moisture and prevent damp

Client Options: Customising Your Insulation

While our standard methods provide excellent results, we also offer custom insulation solutions depending on your preferences, property type and budget.

1. Spray Foam Insulation

Fills every gap and crack, ideal for irregular or complex roof shapes
Provides excellent airtightness
Slightly more expensive and must meet specific ventilation standards

2. Multi-Layer Reflective Foil Insulation

A thinner option that can be used in conjunction with other materials
Good for space-constrained lofts
Ideal for secondary insulation layers

3. Eco-Friendly Insulation (e.g. Sheep's Wool)

Great for eco-conscious homeowners
Renewable and recyclable
Slightly lower thermal performance than synthetic options but excellent moisture regulation

We’ll walk you through the pros and cons of each option and suggest what will work best in your specific loft design.

Avoiding Condensation and Overheating

A common concern in poorly insulated lofts is condensation. It occurs when warm, moist air meets cold surfaces. To prevent this we use breathable membranes, vapour control layers and ensure all materials are properly installed.

We also factor in solar gain and heat retention. Loft spaces can overheat in summer, especially with large roof windows. That’s why we recommend solar control glazing, ventilation options and thermal blinds where necessary.

Let Us Handle the Details

Insulation isn’t the most glamorous part of a loft build but it’s one of the most important. With The Loft Build Company you can rest assured that every layer is professionally installed, fully compliant and designed for maximum comfort.

We help you choose the right insulation for your needs, explain all your options and make sure your loft stays comfortable, dry and efficient all year long.

Want to learn more? Browse more tips on The Loft Edit or contact us for a consultation on your upcoming project.