Insulation: Can You Ever Have Enough?

Short answer: almost certainly not.
Longer answer: many UK homes have some insulation, but far fewer have the right amount, in the right places, installed to modern standards.

This blog looks at the crucial difference between what you have and what you should have – and why that gap matters for your comfort, bills, and carbon footprint.

---

What Most Homes Have

If your house was built before the 2000s, typical insulation looks like this:

🏠 Loft

• 100–150 mm of mineral wool

• Often patchy, compressed, or missing at the edges

🧱 Walls

• Cavity walls: may have older blown insulation (or none at all)

• Solid walls (common pre-1920): usually uninsulated

🪵 Floors

• Timber floors with no insulation underneath

• Draughts coming up through gaps you only notice in winter

🚪 Windows & doors

• Double glazing, but with:

  • Poor seals

  • Thermal bridges around frames

This setup was once considered “reasonable”. By today’s standards, it’s leaky.

---

What You Should Have (Modern Expectations)

Current best practice – and what building physics actually wants – looks very different:

✅ Loft Insulation

• 300–400 mm of insulation

• Continuous, uncompressed, with raised boarding if needed

✅ Walls

• Fully filled cavity walls or

• Internal/external solid wall insulation where cavities don’t exist

✅ Floors

• Insulated between joists (rigid board or mineral wool)

• Airtight membrane to stop cold air movement

✅ Airtightness

• Sealed gaps around:

  • Loft hatches

  • Pipes

  • Cable runs

  • Door frames

This doesn’t just reduce heat loss – it stabilises indoor temperature, making heating systems far more effective.

---

The Key Difference: Thickness and Continuity

The biggest misconception is thinking:

“I’ve got insulation, so I’m fine.”

In reality:

• Thin insulation slows heat loss

• Thick insulation dramatically reduces it

• Gaps undo everything

Heat loss doesn’t scale linearly. Doubling insulation thickness can more than halve heat flow.

That’s why:

• Topping up insulation often gives better returns than a new boiler

• Insulation improvements keep working every hour of every year

---

Comfort vs Cost vs Carbon

Good insulation gives three wins at once:

🌡 Comfort

• Fewer cold spots

• Less need to “turn it up”

• Warmer walls = less condensation and mould

💷 Cost

• Lower heating bills

• Smaller heating system required

• Heat pumps work far better in well-insulated homes

🌍 Carbon

• Less energy needed overall

• Bigger emissions savings than most “smart” gadgets

---

Can You Over-Insulate?

In practice, no – not in UK homes.

The real risks come from:

• Poor ventilation

• Trapped moisture

• Bad installation

Which is why insulation should always be paired with:

• Controlled ventilation (trickle vents, MVHR where appropriate)

• Moisture-aware materials

• Proper detailing

Insulation itself is rarely the problem. Bad design is.

---

The Takeaway

Most homes aren’t under-heated – they’re under-insulated.

The gap between what you have and what you should have is often:

• Invisible

• Above your ceiling

• Under your feet

• Inside your walls

And closing that gap is one of the cheapest, simplest, and greenest upgrades you can make.

---