Home improvements: thermal insulation

By Jeff Howell 1100AM GMT seventeen March 2010

Jeff Howell gives on-the-level recommendation Photo MARTIN POPE

Q My smallish kitchen has discriminating floorboards with a integrate of mats, and is frozen in cold weather. I have to dance around on the building to stop my feet branch in to blocks of ice. Since there is an airbrick in the outward wall, I had regularly insincere there would be a feet of space underneath the floorboards, but I had to take one up and found to my abhorrence I was staring in to a chasm. The residence is on a bank (two storeys at the front and 3 at the back) and the opening underneath the kitchen building slopes down to 8ft (2.5m) at one end. What is the majority appropriate and cheapest solution? RW, Sheffield

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A The majority fit insulation element is firm PIR board, such as Kingspan or Celotex (as well as a little own-brand traffic names from builders merchants, that competence be cheaper). This is some-more costly than polystyrene or mineral-wool fibre, but given it will do some-more to reduce your heating bills, it should work out cheapest in the prolonged run. Get the thickest PIR residence you can means (available in thicknesses up to 200mm), cut it to size, and pull it up in in between the building joists to hold the undersides of the floorboards.

The majority fiddly piece will be measuring and slicing it to fit in in between the joists in an comparison skill these are doubtful to be uniformly spaced. Secure the insulation in place with nails, or joist battens tacked or screwed to the sides of the joists.

You are advantageous in carrying space to work in from below. Readers with a small opening next their ground-floor joists will have to do the work from above, by light the floorboards, regulating battens to the sides of the joists and pulling the insulation down onto them.

You competence be means to get afar with light usually a couple of play each sixth one, contend and pulling the insulation along. This pretence functions improved with semi-stiff mineral-wool batts, however, and is harder to do with firm insulation residence materials.

As with any form of thermal insulation, perfectly you should fit a polythene effluvium separator on the "warm" side (that is, the room side), to stop warm, wet air from inside of the residence anticipating the approach by to the cold side, and causing condensation. As prolonged as the subfloor space is well ventilated, however with air bricks front and back to yield a great through-flow of air afterwards this is not essential.

The value of you do the work from above, and light all the floorboards, is that you can lay a successive effluvium separator opposite the total room, and sign it to the walls at the trimming play to illustrate on condition that a utterly draught-proof floor. This additionally allows for the floorboards to be firmly butted up to each other, you do afar with irritating decline gaps.

Send your questions to Jeff at Life, The Sunday Telegraph, 111 Buckingham Palace Road, London SW1W 0DT or email askjeff@telegraph.co.uk The SundayGuide to Looking After Your Property by Jeff Howell is accessible fromBooks (0844 871 1515; books.telegraph.co.uk) for �13 and �1.25 p&p.