3. Loft Insulation

Take care going into your loft. Avoid using a step ladder. Wear a cycle helmet (yes we know it looks silly). Take a torch. And try not to put your foot through the ceiling.

How much loft insulation does your home have?

1. Less than 15cm deep (which means you can clearly see the ceiling rafters)

2. More than 15cm deep (which means the rafters are hidden)

3. We live in a chalet bungalow so we don’t have a proper loft – do we? (Clue. See below)

4. No idea. It’s full of the children’s toys/my partner’s/ex-partner’s stuff and there’s no light switch. I last went up there in 1993 to remove a dead pigeon from the water tank.


Going through the roof

•Heat loss can be reduced by laying rolled thermal insulation between the ceiling rafters. The cost of adding insulation will pay you back, right up to a thickness of 27cm. This is incredibly cost-effective – as in an uninsulated house – around 25% of heat loss will occur through the roof.
•Increasing the amount of loft insulation is simple and cheap. A competent DIY-er can do this – just add to the insulation already there (after you’ve tidied it up and laid a vapour barrier – see below) between the ceiling rafters until the overall depth of the insulation reaches the top of these.
•You can continue to add more, for the second layer roll out the insulation at right angles to the ceiling rafters.
•Batt insulation (pre-cut flat pieces) can be used to create an accessible area for storage and/or around the water tank.
•Insulate the loft hatch where you can.
•Items to check as you proceed are: (1) pipework lagging. The loft will get colder with an increased risk of pipes freezing in sub-zero temperatures, (2) Vapour barrier. Once you build up the insulation you will need to include this – normally a 50cm wide polythene roll, (3) Eaves ventilation. You can buy proprietary brand trays or baffles, to stop loft ventilation becoming obstructed by the new insulation at the eaves.


For loft conversions and chalet bungalows – insulate accessible attic crawl spaces in the same way, and additionally run the insulation onto the backs of the attic room stud walls.

A thermal imaging camera used for a thermal image camera survey(postcard 7) will help identify any poorly insulated areas to dormers and attic rooms, such as where insulation fitted between rafters for sloping sections of ceiling is missing. Insulating wallpaper may be a solution if just small localisedareas of missing insulation are picked up in the survey.

CAUTION: Unfortunately, sprayed expanding foam applied to the underside of the roof, has previously been sold as a heat loss solution. However, there are now concerns that it causes its own problems including poor air circulation, increased condensation and even rotting timbers. This has left some homeowners unable to sell or remortgage their home.

Issued September 2022

Take part at your own risk.