Loft insulation: topping up the floor of your loft

Mineral wool or similar quilt is laid between the ceiling joists and a second layer across them, so the joists no longer act as cold bridges. Blown loose-fill is an alternative where access is awkward. An existing thin layer can usually stay and be topped up, as long as it is dry and not contaminated.

The loft hatch is often forgotten: an uninsulated, draughty hatch lets warm, moist air straight into the cold loft. Insulating and draught-stripping it should be part of the job. HMRC even gives the example of cutting a new hatch to reach the loft as part of a zero-rated insulation job.

Care must be taken not to block the ventilation at the eaves, which keeps the roof timbers dry. Insulation pushed hard into the eaves is a common cause of condensation and mould on the underside of the roof. Installers often fit eaves ventilators or trays to hold the insulation back.

Once the loft floor is insulated, the loft gets colder. Cold water tanks and pipes up there need insulating, and the insulation under a tank is normally left out so a little warmth from below keeps it from freezing. Ask how the installer will deal with the tank and every pipe run.

Boards laid straight on the joists squash the insulation and leave little room for it. If you want to store things in the loft, ask for boarding raised on legs or a raised platform above the full depth of insulation, and for that part of the loft to be kept small.

Recessed downlights in the ceiling below can poke up into the insulation; they need suitable covers or fittings so they do not overheat or leak air. Cables buried under insulation can run warmer than intended, so the installer should point out any wiring that needs an electrician's look. Old wiring, signs of pests or damp timbers should be fixed before new insulation goes down.

Installing insulation in a roof space is exempt from Building Regulations approval. Where loft insulation is upgraded, Approved Document L gives an improved U-value for roofs of 0.16 W/m²K; if that is not technically or functionally feasible, the aim is the best standard achievable with a simple payback of no more than 15 years. If you are also renewing a quarter or more of the roof covering, the insulation standard in the Building Regulations applies.

Installing insulation in a home is zero-rated for VAT until 31 March 2027. Low-income households may get loft insulation free or subsidised through ECO4 or, in England, a council's Warm Homes: Local Grant. In Scotland, loft insulation can be funded by Home Energy Scotland if your EPC recommends it.

• depth and type of insulation, and whether existing material stays
• eaves ventilation kept clear
• tank and pipe insulation, and the hatch
• raised boarding if you need storage
• downlights and cables flagged
• clearing and disposal of old material if needed

Source: gov.uk · planningportal.co.uk

Tell us the house type, what is in the loft now and whether you need storage space. Insulation installers in your area see the request without your personal details, and the first to buy it is the only one who gets it. They pay Offrano; you pay nothing.

We email you the installer's name, address and phone number before your details go to them. We cannot promise that a small job like this will be taken, and unsold requests are withdrawn after 21 days. We check that the buyer is a registered business, not its work, so ask what it will do about the eaves, tanks and boarding before you agree.