Mike Wray
The right insulation can be a gamer changer!
Loft insulation is one of the simplest ways to make your home warmer, reduce energy bills, and improve energy efficiency. But what exactly is it and how does it work?
In this guide, we’ll break down everything you need to know about loft insulation, from how it prevents heat loss to the different types used in UK homes.
What Is Loft Insulation?
Loft insulation is a layer of insulating material installed in your roof space (loft) to reduce heat escaping from your home.
In most UK properties, heat rises naturally and escapes through the roof. Without insulation, up to 25% of your home’s heat can be lost through the loft.
Pro Tip: Loft insulation acts as a thermal barrier, keeping warm air inside during winter and helping keep your home cooler in summer.
How Does Loft Insulation Work?
Loft insulation works by slowing down heat transfer through three main processes:
1. Conduction (heat passing through materials)
Insulation materials trap air pockets, which are poor conductors of heat.
2. Convection (heat carried by air movement)
By reducing airflow, insulation prevents warm air from escaping.
3. Radiation (heat energy transfer)
Some materials reflect heat back into the living space.
Pro Tip: The effectiveness of insulation is measured by its thermal conductivity and U-value (lower is better).
Types of Loft Insulation (UK)
1. Mineral Wool Insulation (Most common)
- Made from glass or rock fibres
- Comes in rolls or slabs
- Affordable and easy to install
Popular brands include Knauf Insulation and Rockwool
Pro Tip: Best for standard lofts and general use.
2. Rigid Insulation Boards (PIR)
- Dense foam boards with high thermal performance
- Used in loft conversions or where space is limited
Common brands: Celotex and Kingspan
Pro Tip: Ideal when you need maximum insulation with minimal thickness.
3. Loose-Fill Insulation
- Made from lightweight materials (e.g. cellulose or mineral fibres)
- Blown into gaps or irregular spaces
Pro Tip: Good for hard-to-reach areas.
4. Spray Foam Insulation
- Expands to fill gaps and create an airtight seal
- Provides strong thermal performance
Note: More expensive and may impact property resale or mortgage approvals.
Recommended Loft Insulation Thickness (UK)
Current UK guidance recommends:
- 270mm thickness for mineral wool insulation
This is usually achieved by:
- 100mm between joists
- 170mm laid across joists
Pro Tip: Proper thickness is key to achieving maximum energy efficiency.
Benefits of Loft Insulation
- Lower energy bills: Reducing heat loss means your heating system works less.
- Warmer home: Keeps indoor temperatures stable during colder months.
- Environmental impact: Lower energy usage reduces your carbon footprint.
- Increased property value: Improves your home’s EPC rating.
Where Is Loft Insulation Installed?
There are two main approaches:
1. Cold loft insulation (most common)
- Insulation placed between and over joists
- Keeps heat in the living space below
2. Warm loft insulation
- Insulation placed under the roof
- Used for loft conversions or habitable spaces
How Loft Insulation Is Installed
Typical process:
- Inspect loft space
- Clear or lift existing boarding
- Lay insulation between joists
- Add second layer across joists
- Replace or raise boarding if needed
Most installations take 2-4 hours for a standard loft.
How Much Does Loft Insulation Cost?
Costs vary depending on materials and installation, but typically:
- £5-£15 per m² (materials)
- £15-£40 per m² (installed)
👉 You can read a full breakdown in our guide to loft insulation costs.
Do You Need Loft Insulation? (Quick Checklist)
You likely need insulation if:
- Your home feels cold in winter
- Energy bills are high
- Your loft insulation is less than 270mm
- Your property has a low EPC rating
Best Selling Loft Insulation Boards
- Superior Loft Boards (1220mm x 320mm x 18mm – Pack of 3): Durable and strong, perfect for general loft storage.
- Supreme Moisture-Resistant Loft Boards (1220mm x 320mm x 18mm – Pack of 3): Ideal for humid environments, offering added protection against moisture.
- Eco Loft Boards (1220mm x 310mm x 18mm): A sustainable option for environmentally conscious projects.
- High-Performance Wood Screws (4mm x 40mm – Box of 200): Designed for secure and efficient installation.
FAQs
What is the purpose of loft insulation?
To reduce heat loss through the roof and improve energy efficiency in your home.
How effective is loft insulation?
It can reduce heat loss by up to 25%, making it one of the most effective home upgrades.
What is the best type of loft insulation?
Mineral wool (e.g. Knauf Insulation) is the most common, while PIR boards offer higher performance.
Can I install loft insulation myself?
Yes, especially roll insulation. However, professional installation ensures correct coverage and thickness.
How long does loft insulation last?
Typically 40+ years with minimal maintenance.
Does loft insulation stop condensation?
It can help, but proper ventilation is also essential to prevent moisture build-up.
Is loft insulation worth it?
Yes, it offers one of the highest returns on investment for energy-saving home improvements.
How do I check my current insulation?
Measure the depth of insulation in your loft. If it’s below 270mm, it likely needs topping up.
Conclusion
Loft insulation is a simple, cost-effective solution that delivers long-term benefits for comfort, energy savings, and property value.
Whether you’re upgrading existing insulation or starting from scratch, understanding how it works helps you make the right decision for your home.
Explore our Loft Boards Collection to get started on your project today. If you have any questions or need advice, contact our sales team at 02030 045 451 – we’re here to help!