Choosing the best type of loft insulation is crucial for improving energy efficiency, cutting heating bills, and maintaining a comfortable temperature year-round. With so many options available, it can be difficult to know which material suits your property best.
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In this guide, we compare the top 6 types of loft insulation commonly used in the UK, covering their pros, cons, typical costs, and best applications for homes and businesses.
Best loft insulation types compared
| Type of insulation | Pros | Cons | Typical cost (per m²) | Best for |
|---|---|---|---|---|
| Mineral wool | Affordable, easy to install, fire resistant | Irritant to skin, bulky | £5–£10 | Budget-friendly home insulation |
| Sheep’s wool | Natural, breathable, non-irritant | Expensive, needs treatment for pests | £12–£20 | Eco-conscious and older homes |
| Spray foam | Airtight, very efficient | Expensive, needs professional installation | £30–£50 | Hard-to-reach loft spaces |
| Rigid board (PIR) | Thin, high-performance, durable | Higher cost, requires precise fitting | £15–£30 | Loft conversions and businesses |
| Multifoil | Space-saving, lightweight, reflective | Lower standalone thermal performance | £10–£20 | Tight spaces and upgrades |
| Blown-fibre | Fills gaps thoroughly, quick to install | Settles over time, needs a professional | £15–£25 | Uneven or awkward loft spaces |
1. Mineral wool insulation (glass or rock wool)
Mineral wool, either made from glass fibres (glass wool) or stone fibres (rock wool), is the most widely used type of loft insulation in the UK.
Pros:
- Very affordable
- Easy to install (DIY-friendly)
- Excellent thermal and acoustic insulation
- Non-combustible
Cons:
- Can irritate skin and lungs during installation
- Bulkier than some modern materials, so needs adequate loft height
Typical cost: £5–£10 per m² (materials only)
Best for: Domestic homes, quick energy upgrades, and properties needing low-cost solutions.
2. Sheep’s wool insulation
A natural, sustainable alternative, sheep’s wool offers superb insulation with additional moisture control benefits.
Pros:
- Naturally regulates humidity
- Breathable and sustainable
- Non-irritant and safe to handle
- Great acoustic properties
Cons:
- More expensive than synthetic options
- Can attract moths if not treated
Typical cost:
£12–£20 per m²
Best for:
Eco-conscious homeowners, listed buildings, and properties in damp climates.
3. Spray foam insulation
Spray foam is applied as a liquid that expands and hardens to fill all gaps, creating an airtight barrier.
Pros:
- High thermal efficiency
- Excellent at sealing draughts
- Reduces air leakage dramatically
Cons:
- High installation cost
- Must be professionally installed
- Can complicate future roof repairs and mortgage applications
Typical cost: £30–£50 per m²
Best for: Hard-to-reach loft spaces, commercial properties, and buildings needing airtightness upgrades.
4. Rigid board insulation (PIR boards like Celotex or Kingspan)
Rigid boards made from polyisocyanurate (PIR) or similar materials offer high performance with thinner layers.
Pros:
- Very high thermal resistance
- Saves space due to thinner profile
- Long-lasting and robust
Cons:
- More expensive than rolls
- Requires accurate cutting and fitting
Typical cost: £15–£30 per m²
Best for: Loft conversions, businesses needing additional storage space, and projects with limited headroom.
5. Multifoil insulation
Multifoil insulation consists of several reflective layers and insulation sheets, offering a slim, flexible solution.
Pros:
- Very thin, perfect where space is limited
- Reflects heat back into the property
- Lightweight and easy to install
Cons:
- Lower thermal performance compared to thicker options unless combined with other insulation
- Can be expensive per m²
Typical cost: £10–£20 per m²
Best for: Loft conversions, tight spaces, and properties needing additional thermal upgrades without losing usable space.
6. Blown-fibre insulation
Blown-fibre insulation involves loose fibres being blown into loft cavities, particularly useful for awkward spaces.
Pros:
- Fills all gaps thoroughly
- Good for uneven lofts or hard-to-reach areas
- Quick installation process
Cons:
- Settles over time, reducing effectiveness
- Professional installation usually required
Typical cost: £15–£25 per m²
Best for: Old houses with irregular loft spaces and commercial buildings with difficult roof structures.
Conclusion – Which loft insulation is best for you?
- Best low-cost option: Mineral wool insulation
- Best eco-friendly option: Sheep’s wool insulation
- Best for tight spaces: Multifoil insulation
- Best for maximum energy savings: Spray foam or rigid board insulation
- Best for awkward loft spaces: Blown-fibre insulation
The right choice depends on your budget, loft structure, and priorities — whether it is cost, sustainability, maximum warmth, or preserving space.
If you are still unsure, it is always worth consulting an insulation specialist who can survey your loft and recommend the most effective solution for your particular property.