How to buy loft insulation Installing sheet insulation

Sheet insulation

Sheet or board insulation is a good choice for loft conversions

If you're planning a loft conversion or already use your loft as an extra room, insulating the sloping surfaces of your roof using sheet insulation can be a good alternative option to insulating the floor – but expect to pay more for this type of material than other types of loft insulation.

Fitting sheet insulation

This type of insulation is fixed between the roof rafters rather than between joists, and like blanket insulation it can be cut to fit or bought in pre-cut packs.

To avoid condensation, always leave sufficient space between the insulation and roof slates or tiles to allow for ventilation. It's also important to check the roof has no leaks or weaknesses that could let in damp before you start the work.

If the width of your roof rafters are too thin for sheet insulation, you could consider using foiled quilt insulation instead.

Sheet insulation can be covered with plasterboard once laid to give a clean finish.

Pipe insulation

Don't forget that pipes also give off heat - pipe insulation is cheap and easy to install

Before installing insulation

Whatever type of insulation you choose, you'll need to make a few preparations before you start - and if you're unsure what insulation will suit your loft best, consult a professional.

Clearing your loft

Even if you’re getting a professional loft insulation installer to complete the work for you, you’ll usually need to clear your loft before they arrive.


Wiring needs to be dealt with safely. Wires should be kept above the insulation but not stretched if they don’t comfortably reach. An electrician will be able to re-route any problematic wiring. You can use our Which? Trusted Traders service to find a recommended electrician near you.

Pipes and tanks

Pipework and tanks in the loft should also be insulated correctly, as less heat will be escaping into the loft and protecting pipes from freezing.

If in doubt

Insulation must be installed following the manufacturer's instructions to achieve the full benefit. If you're unsure about any aspect of insulating your loft, you should contact a professional insulation fitter.

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