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Home & garden.

30 June 2021

Installing blown insulation

Considering installing blown-fibre insulation? Make sure you know how it’s fitted and what you need to do before blown-fibre insulation’s installed.
Which?Editorial team
Blown fibre insulation2 450365

Installing blown-fibre insulation will help you to cut your energy bills. Find out what you need to know about blown-fibre insulation.

Blown-fibre insulation is made up of mineral fibres. In most cases you’ll need to hire a professional to install blown insulation, as it needs to be blown into place with specialist equipment. So bear this in mind when you’re budgeting.

Fitting blown-fibre insulation

With this type of insulation, mineral fibres are evenly blown and spread between the joists in your loft using specialist industrial equipment. Blown-fibre insulation works well in lofts where the use of blanket insulation isn’t suitable, or if your joists are obstructed.

It’s a fairly quick job for a professional to do. Which? Trusted Traders can help you find recommended loft-insulation installers, as well as electricians and plumbers, in your area.

Before getting blown-fibre insulation installed

Whatever type of insulation you choose, you’ll need to make a few preparations before you start – ask your installer if they have any particular requirements.

Clearing your loft

You’ll need to clear your loft before your professional installer arrives, unless you’ve agreed beforehand that clearing your loft is part of the work.


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 reroute any problematic wiring.

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.

Thinking of getting a loft conversion? Find out what you need to know - we reveal loft conversion insider tips from owners and experts.