Damaged insulation is usually described as something to tidy up. It is better understood as a bill that arrives every month until it is dealt with.
Why the roof matters more than anything else
A substantial share of the heat lost from a typical house goes through the roof, because heat rises and the roof is the largest surface it meets. Loft insulation is the cheapest and most effective single intervention available against that, which is why it is the first thing every energy-efficiency scheme addresses.
It follows that insulation which is not working is not a cosmetic problem. It is the most cost-effective part of the building envelope, switched off.
How the damage reduces performance
- Compression. Mineral wool works by trapping still air. Flatten it and most of the performance goes with the thickness — a squashed track is close to no insulation at all
- Hollowing. A nest bowl exposes bare plasterboard. That area is uninsulated ceiling
- Displacement. Batts pushed off the joists leave whole bays uncovered, and a bay is a large area
- Wetting. Where the roof covering has also been breached, wet mineral wool performs far worse than dry and stays wet for a long time in an unventilated loft
- Gaps at the eaves. Material pushed away from the edges leaves the coldest part of the ceiling bare
The thickness is the performance. Insulation is specified in depth because depth is the mechanism. Anything that reduces the depth reduces the effect roughly in proportion, which is why compression matters as much as removal.
The invisible part
Two features make this easy to under-rate. It is above a ceiling, so nobody sees it. And it costs a little every day rather than a lot at once, so it never presents as an event — the house is simply slightly harder to heat than it was, which gets attributed to the weather or to prices.
The comparison worth making
Reinstating a loft's insulation is an ordinary job with an ordinary cost. Running a house through several winters with a season's worth of squirrel damage in the roof is a recurring one. Set alongside £280 for the control work and £180 for closing the roof, the case for dealing with it in one go rather than living with it is not a close call.
Doing it properly when you do
- Remove contaminated material rather than covering it
- Lay to a consistent depth across the whole ceiling, not just the middle
- Carry it out to the eaves without blocking the ventilation path
- Do not compress it under boarding — if the loft is boarded, the boards want raising above the insulation
- Insulate the hatch itself, which is frequently forgotten and is a large cold spot
Questions
Can flattened insulation recover?
Not usefully. Once compressed it stays compressed, and the trapped air that did the work has gone.
Is it worth replacing the lot or just the damaged part?
Where the rest is in good condition and of adequate depth, the damaged area alone. Where it is old, thin or contaminated throughout, doing the whole ceiling is usually better value.
Should I insulate before or after proofing?
After. Fresh insulation in a roof that is still open is simply new bedding for whatever comes next.
Squirrel Control Woodbridge
Squirrel control in Woodbridge is £280 fixed cost. Proofing work, where it is needed afterwards, is £180. Call 01502 630 122 and tell us what you have heard or seen.
For squirrel control in Woodbridge, call 01502 630 122, or read the Woodbridge squirrel control page.