Comparing Insulation Types: Which Has the Best Payback Period?

When upgrading your home's energy efficiency, insulation is one of the smartest investments you can make. But not all insulation types are created equal — especially when it comes to cost, effectiveness, and payback period. In this post, we’ll break down the most common insulation options, what they cost, and how quickly you can expect to recoup your investment through energy savings.

Why Payback Period Matters When Comparing Insulation Types

The payback period is the time it takes for your energy bill savings to cover the cost of installing the insulation. The shorter the payback period, the faster your upgrade pays for itself — and starts saving you money.

1. Loft Insulation (Mineral Wool or Fibreglass)

Average cost: £300–£500 (DIY) Savings/year: £250 + Payback period: 1–2 years

Loft insulation is one of the most cost-effective improvements you can make. If your loft is currently uninsulated or under-insulated, topping it up to the recommended 270mm can significantly cut heat loss.

✅ Best for: Quick returns and lower upfront costs

🚫 Watch out for: Gaps around joists or pipes that reduce effectiveness

2. Cavity Wall Insulation

Average cost: £700–£1,000 (for a semi-detached home) Savings/year: £250 + Payback period: 3–4 years

If your home was built after the 1920s, chances are it has cavity walls that can be filled with insulating material. It's relatively quick and minimally invasive, and many UK homes still haven’t had it done.

✅ Best for: Homes built after 1920s with uninsulated cavity walls

🚫 Watch out for: Damp issues in poorly maintained walls

3. Floor Insulation

Average cost: £1,200–£1,800 Savings/year: £100–£150 Payback period: 8–12 years

Insulating under suspended timber floors helps reduce draughts and retain heat in older homes. It’s more expensive and intrusive than loft or wall insulation but can make a big difference in comfort levels.

✅ Best for: Older homes with accessible floor voids

🚫 Watch out for: Ventilation blockages that could cause damp

4. Solid Wall Insulation (Internal or External)

Average cost: £7,000–£15,000 Savings/year: £400–£500 Payback period: 15–30 years

Solid walls (common in pre-1920s homes) let through twice as much heat as cavity walls. Insulating them is highly effective — but also one of the most expensive upgrades, with a long payback period.

✅ Best for: Period homes with poor heat retention

🚫 Watch out for: Moisture issues and planning restrictions

5. Spray Foam Insulation

Average cost: £2,000–£3,500 (roof or loft area) Savings/year: £200–£300 Payback period: 8–12 years

Spray foam can be effective, but it’s controversial. Some mortgage lenders refuse properties with spray foam due to moisture trapping risks and inspection difficulties. At Absolute Interior Solutions, we do not recommend spray foam insulation for homeowners and advise against it in most domestic applications.

✅ Best for: Very specific commercial or industrial uses

🚫Watch out for: Reduced ventilation, trapped moisture, mortgage issues

So, What’s the Best Option?

Type	Avg Cost	Savings/yr	Payback
Loft Insulation	£300–£500	£250+	1–2 yrs
Cavity Wall	£700–£1,000	£250+	3–4 yrs
Floor Insulation	£1,200–£1,800	£100–£150	8–12 yrs
Solid Wall	£7,000+	£400–£500	15+ yrs
Spray Foam	£2,000+	£200–£300	8–12 yrs

How Absolute Interior Solutions Can Help

At Absolute Interior Solutions, we specialise in safe, effective, and mortgage-friendly insulation methods like loft and cavity wall insulation. Our team can:

• Survey your home and recommend the most cost-effective improvements

• Handle the installation quickly and professionally

• Help you qualify for government schemes (like the Great British Insulation Scheme)

• Ensure all work is compliant and fully certified

  
  

Final Thoughts

If you’re looking to compare insulation types for your home, loft and cavity wall insulation offer the best balance of cost and payback. And with rising energy prices, every month you wait is money lost.

Have questions?

Contact Absolute Interior Solutions today for a free insulation survey.