Blown (loose-fill) loft insulation
Loose fibres blown into the loft through a hose until they form an even blanket. It gets into corners and around obstacles that rolls struggle with, and suits lofts that are hard to get around in.
| What it is | Loose mineral wool fibres or cellulose (recycled paper) blown in by machine |
|---|---|
| Comes as | Bags, fed into a blowing machine |
| Typical lambda | Around 0.035 to 0.045 W/mK, depending on the material |
| Fitted | Blown through a hose to an even depth, with depth markers |
| Best for | Low, cramped or awkward lofts, and topping up around obstacles |
How it’s installed
The machine stays outside or downstairs and a hose is run up into the loft. We blow the fibres across the loft floor until they reach the right depth, measured against markers fixed to the joists. Because the fibres flow, they fill gaps around joists, pipes and cross-bracing far more evenly than rolls cut to fit.
When it’s a good fit
- Lofts with low headroom where crawling around laying rolls is difficult
- Lofts full of trusses, braces and obstacles
- Topping up an uneven layer of existing insulation
- Where an even layer with no gaps matters most
Things to watch
- Loose fill moves about in a draught and doesn’t like being walked on. Boarding needs to be raised well above it, and the eaves need trays or barriers to stop it blocking ventilation.
- It settles a little over time; we allow for this in the depth.
- Fibres can drift through gaps around downlights and the hatch, so those need sealing first.
Common questions
Is blown insulation messy?
The work is done in the loft through a hose, so the rest of the house stays clean if the hatch is sealed off. We put down protection on the landing.
Can I store things on blown insulation?
Not directly. Anything placed on it squashes it. If you want storage, ask for raised boarding fitted above the insulation.
Ready for a free loft insulation quote?
Tell us about your home and we’ll give you a written quotation before any work begins.