Mike Wray
The right insulation can be a gamer changer!
Choosing the right insulation for your loft can significantly reduce energy bills, improve comfort, and increase your property’s value. But one question UK homeowners often ask is:
Should I choose traditional loft insulation or spray foam insulation?
Both options have their advantages and the “best” choice depends on your home, budget, and long-term plans.
Let’s break it down clearly.
What Is Loft Insulation?
Loft insulation typically refers to mineral wool rolls or rigid boards laid between and over joists.
Popular materials include:
- Fibreglass or mineral wool (e.g. from brands like Knauf Insulation)
- Rigid PIR boards (e.g. Celotex or Kingspan)
Pros:
- Cost-effective (one of the cheapest insulation types)
- Easy to install or top up
- Widely accepted by mortgage lenders
- Works well with UK building regulations
Cons:
- Doesn’t seal air gaps completely
- Can lose performance if poorly installed
- Requires correct ventilation
What Is Spray Foam Insulation?
Spray foam is a chemical insulation applied as a liquid that expands into foam, filling gaps and sealing surfaces.
It comes in two types:
- Open-cell (softer, breathable)
- Closed-cell (denser, higher insulation value)
Pros:
- Excellent air sealing (reduces drafts significantly)
- High thermal performance
- Helps prevent moisture ingress
- Ideal for awkward or hard-to-reach spaces
Cons:
- Much more expensive than traditional insulation
- Can affect mortgage or resale value if not installed properly
- Difficult to remove once applied
- Requires specialist installation
Cost Comparison (UK)
| Type | Average Cost (UK) |
| Loft insulation (roll) | £400 - £1,200 |
| Loft insulation (boards) | £1,000 - £2,500 |
| Spray foam insulation | £2,000 - £5,000+ |
Tip: Spray foam can cost 2-4x more than traditional loft insulation.
Performance Comparison
Thermal performance
- Spray foam: ⭐⭐⭐⭐⭐
- Loft insulation: ⭐⭐⭐⭐
Air sealing
- Spray foam: ⭐⭐⭐⭐⭐
- Loft insulation: ⭐⭐⭐
Cost-effectiveness
- Loft insulation: ⭐⭐⭐⭐⭐
- Spray foam: ⭐⭐
Ease of installation
- Loft insulation: ⭐⭐⭐⭐⭐
- Spray foam: ⭐⭐
Important UK Considerations
1. Mortgage & resale issues
Some UK lenders are cautious about spray foam insulation due to:
- Roof timber visibility concerns
- Potential moisture risks
Tip: Always check before installing.
2. Ventilation matters
Traditional loft insulation requires proper airflow to prevent condensation. Spray foam reduces airflow, which can be beneficial but must be installed correctly.
3. Grants & funding
Most UK schemes like the ECO4 Scheme and Great British Insulation Scheme typically support standard loft insulation, not spray foam.
Which Is Better for Your Home?
Choose loft insulation if:
- You want a cost-effective solution
- You plan to sell or remortgage
- Your loft is accessible and standard
Best for most UK homes
Choose spray foam if:
- You need maximum air sealing
- Your loft has awkward shapes or gaps
- You’re staying long-term and not concerned about resale
Best for specialist or complex properties
Expert Recommendation
For the majority of UK homeowners:
Tip: Traditional loft insulation offers the best balance of cost, performance, and flexibility.
Spray foam is powerful but it’s usually a premium, niche solution rather than the default choice.
Get Expert Advice
Not sure which option is right for your property or have a any insulation related question?
Get expert advice and quote tailored to your home and budget. Contact our sales team at 02030 045 451 – we’re here to help!
FAQs
1. Is spray foam insulation better than loft insulation?
Not necessarily. Spray foam performs better for air sealing, but traditional loft insulation is more affordable and widely accepted in the UK.
2. How long does loft insulation last?
Most loft insulation lasts 20-40 years if properly installed.
3. Does spray foam increase home value?
It can improve energy efficiency, but in the UK it may negatively impact mortgageability if not installed correctly.
4. Can I install loft insulation myself?
Yes, many homeowners install mineral wool rolls themselves. Boards and spray foam usually require professionals.
5. What is the cheapest way to insulate a loft?
Mineral wool loft rolls are typically the cheapest and most cost-effective option.
6. Are there grants for loft insulation in the UK?
Yes. Schemes like the ECO4 Scheme may cover part or all of the cost if you qualify.