Insulation only performs when it is deep enough, continuous, uncompressed and paired with a sealed hatch. Most cold upstairs rooms we see have insulation present — just not working.
On this page
- The common causes
- Causes that are not the loft
- What good looks like
The common causes
- Depth well below current guidance — often 100mm laid decades ago
- Insulation compressed under loft boards or stored items
- Gaps between rolls, or bare patches around the hatch and services
- Insulation stopping short of the eaves, leaving cold edges over the ceiling perimeter
- An uninsulated, undraught-proofed loft hatch acting as an open chimney
- Damp or matted material that has lost its loft
Causes that are not the loft
Cold upstairs rooms can also come from unbalanced radiators, poor cavity wall insulation, draughty windows or an oversized bedroom above an unheated garage. A loft assessment should tell you honestly if the loft is not the problem.
What good looks like
Around 300mm of mineral wool laid in two layers with the top layer crossing the joists, continuous to the eaves without blocking ventilation, a draught-proofed insulated hatch, and lap vents where the roof needs them.
Common questions
Why is my bedroom cold when the loft is insulated?
Usually because the insulation is too shallow, compressed under boards, or interrupted by gaps and an uninsulated loft hatch. Depth alone does not guarantee performance.
If you would like an honest opinion on your own loft, send us your postcode and a few photographs. Most lofts can be assessed and quoted remotely using satellite imagery, and we will tell you if work is not necessary.
Related: Signs your loft is losing heat • Price list • Project planner • Contact