Should You Remove Old Loft Insulation — or Just Top It Up?

This is one of the most common questions we hear from homeowners — especially in properties built before the 1990s. If your loft already has insulation, is it still doing its job, or is it time for a fresh start?

The short answer? It depends on what’s up there. In this guide, we’ll walk you through when to remove, when to top up, and what to avoid — so you can make the right call for your home.

What’s in Your Loft Right Now?

Many UK homes still contain insulation that’s 20, 30, even 40 years old. Back then, building regulations were very different — and so were the materials.

You might find:

• Thin mineral wool or fibreglass
• Patchy rolls compressed over time
• Outdated board-style insulation
• Or worse, spray foam directly on the underside of the roof

It might look like it’s doing something — but in many cases, it’s underperforming badly or even making things worse.

Signs It Should Be Removed

There are clear warning signs that your current insulation needs to come out:

• Damp or condensation
• Visible mould or musty smell
• Compressed or flattened material
• Rodent or pest activity
• Gaps in coverage or uneven layering

Insulation in this state isn’t just inefficient — it can encourage rot in roof timbers, reduce airflow, and contribute to poor air quality inside your home.

Can I Just Top It Up?

In some cases, yes — if your existing insulation is:

• Clean
• Dry
• Free from gaps or contamination

You might be able to top it up to meet today’s recommended depth of 270mm. But be careful — stacking new material on top of old can seal in moisture, disrupt ventilation, and reduce the effectiveness of the system as a whole.

In older homes, starting fresh often leads to better, longer-lasting results.

What About Foam or Board Insulation?

This is where things get tricky.

• Old foam boards can block airflow and trap heat in the wrong places
• Spray foam may affect mortgageability or surveyor access — even if it's decades old

These materials almost always need full removal. Learn more about that process on our Spray Foam Removal page.

Why We Often Recommend Full Removal

We’re not quick to recommend ripping everything out — but here’s what full removal allows us to do:

• Check the structure – Spot hidden damage, gaps, or rot
• Clean the loft properly – Get rid of dust, debris, or nesting
• Install insulation evenly – Using modern, breathable materials
• Ensure airflow – So your loft stays dry and your timbers stay healthy

Think of it like replacing old carpet — sure, you could lay the new over the old, but it won’t feel (or perform) right unless the base is sorted first.

What’s the Best Option for You?

At Snug & Secure, we don’t believe in one-size-fits-all. Every loft we assess gets a proper look — and we’ll talk through your options clearly.

Sometimes it makes sense to top up. Other times, starting again saves money and stress long term.

You can contact us for a free, no-pressure quote — or browse our full blog for more straightforward advice.

Final Thoughts

If your insulation is more than 15 years old, it’s definitely worth a check.

Loft insulation isn’t just about energy bills — it’s about comfort, home health, and peace of mind. And when done properly, it’s one of the few home improvements that pays for itself year after year.