Loft insulation types compared
Most lofts are insulated with rolls laid on the floor, but there are several materials to choose from. Here is how they compare, and where each one makes sense.
| Material | Typical lambda (W/mK) | Best for |
|---|---|---|
| Mineral wool | 0.032 to 0.044 | Most pitched-roof lofts with a clear floor |
| Sheep’s wool | 0.035 to 0.040 | Older and traditional homes, and people who want a natural material |
| Recycled plastic (polyester) | 0.035 to 0.044 | Lofts where comfortable handling or moisture resistance matter |
| Rigid board (PIR) | 0.022 | Warm roofs, loft rooms, shallow spaces and hatches |
| Multifoil | Depends on how it is fitted | Roof slopes and tight spaces, often combined with other insulation |
| Blown (loose-fill) | 0.035 to 0.045, depending on the material | Low, cramped or awkward lofts, and topping up around obstacles |
Lower lambda means less thickness is needed for the same effect. Ranges are typical; each product’s declaration of performance gives its exact figure. We recommend a material for your loft in our quotation.
- Mineral wool loft insulation
- Glass wool and rock wool rolls: how mineral wool loft insulation works, the depth usually recommended, pros, cons and when it’s the right choice.
- Sheep’s wool loft insulation
- Natural sheep’s wool loft insulation: how it compares with mineral wool, why it suits older and traditional homes, and what to know before choosing it.
- Recycled plastic (polyester) loft insulation
- Polyester loft insulation made from recycled plastic bottles: non-itchy, moisture-resistant and easy to handle. How it compares and when to use it.
- Rigid board (PIR) loft insulation
- PIR and other rigid insulation boards: thin, high-performing insulation for rafters, loft conversions and lofts with little depth. How it works and when it’s used.
- Multifoil loft insulation
- Multifoil (multi-layer reflective) insulation: how it works, where it is used in lofts and roofs, and what to check before choosing it.
- Blown (loose-fill) loft insulation
- Blown or loose-fill loft insulation: how it’s installed, when it suits awkward or low lofts, and what to ask us about it.
Ready for a free loft insulation quote?
Tell us about your home and we’ll give you a written quotation before any work begins.