Insulation can look fine from the hatch and still not be doing its job. Most problems are easy to spot once you know what you are looking at. This guide covers the common ones, how to check for them, and what usually fixes them.
Problem 1: gaps and missed spots
The most common issue is simply incomplete coverage. Batts that do not meet, bare patches around the edges of the ceiling space, and areas left out around hatches, downlights and pipes all let heat through.
How to check: look into the ceiling space with a torch. You should see batts laid snugly side by side, with no daylight-coloured strips of bare ceiling lining between them. Underfloor, look for batts that have dropped or fallen away from the joists.
The fix: fill the gaps, or if the coverage is patchy overall, add or replace. See our ceiling insulation and underfloor insulation pages.
Problem 2: damp
Wet insulation stops working properly, and damp underfloor spaces can cause other problems for the house. Damp can come from a roof leak above, or from moisture rising from the ground below.
How to check: look for stains on the ceiling, a musty smell, or insulation that looks dark, clumped or wet. Under the house, check whether the ground is damp and whether there is any plastic cover over it.
The fix: sort the source of the moisture first. A leak needs repairing. A damp underfloor can benefit from a ground moisture barrier before insulation goes in.
Problem 3: squashed or disturbed batts
Batts work by trapping still air, so they need their thickness. Stored boxes, people walking on them and trades moving through the ceiling space can flatten them, and batts that have been pulled aside to run cables often never get put back.
How to check: if insulation looks flat or has been shoved aside, it is probably not doing as much as it should.
The fix: put it back properly, or replace the affected sections. If you need to store things in the ceiling, use a raised platform rather than stacking on the batts.
Problem 4: pests
Rodents and insects can nest in insulation and leave it chewed, flattened or soiled.
How to check: look for droppings, shredded material, nests and tracks through the batts.
The fix: deal with the pests first, then repair or replace the damaged insulation. Closing off entry points helps keep them out.
Problem 5: old loose-fill insulation
Some older homes have loose-fill insulation, often called Insulfluff. It can settle, clump or get mixed with dust over the years, and it is hard to work around.
The fix: take it out before new insulation goes in. We do this as part of our Insulfluff removal service, so the new insulation can go in on a clean surface.
Signs something is wrong
A single sign does not prove anything on its own, but together these are worth investigating:
- Some rooms stay noticeably colder than others.
- Condensation or mould appears on ceilings or walls.
- Your home feels cold quickly after the heating goes off.
- Insulation you can see is flat, wet, patchy or very old.
When to call someone in
Checking the ceiling space is fine for most people, but take care. Stay on the joists, never step on the ceiling lining, watch for wiring, and wear gloves, a mask and eye protection. If you are not comfortable, or the underfloor space is tight, an assessment is the safer option.
We offer a free consultation and assessment, mostly through our online system, or in person for complicated homes or on request. If you would like us to look at your insulation, get a free, no-obligation quote. We aim to call you back within 48 hours, or phone us on 027 482 0333.