How to insulate the home

Discover all you need to know about double glazing, insulating your walls, and lagging your pipes

Believe it or not, the average uninsulated house loses around 35% of its heat through the walls, 25% through the roof, 25% through draughty doors and windows, and 15% through the floor.

1. Secondary, double, and triple glazing

If you add a second sheet of glass or plastic to a window, it traps a layer of air - which acts as an insulator and reduces draughts, condensation, and noise. Although it doesn't have a dramatic effect on overall heat loss (only about 5%), it does make rooms warmer and quieter near the windows.

With secondary glazing, a frame containing a pane of glass (or plastic) is fixed over the existing window frame, leaving an air gap between. You can get simple secondary glazing kits (usually made from aluminium and plastic) in a range of sizes.

Sealed double and triple glazing comprises two or three panes separated by spacing strips, bonded together and hermetically sealed at the factory before being fitted into the window frame. Inert gases that give extra sound and heat insulation can also be sealed inside the gap.

2. Lagging your cylinders, tanks, and pipes

It's well worth lagging your hot-water cylinder by fitting it with a jacket made from mineral-fibre insulation. If you're buying a new cylinder, choose one with foam insulation already fitted. Also, make sure you lag your cold water pipes in your loft and any exposed hot-water pipes running through unheated areas of your home with split foam tubes.

You should also insulate your cold-water cistern and the small feed-and-expansion tank (if you have one). You can wrap the cistern in a purpose-made jacket or a glass-fibre blanket. But don't insulate the area underneath it - any heat rising from the room below will help to prevent the tank from freezing.

3. How to insulate your walls

Insulating your walls to cut heat loss is a bigger, more expensive job than insulating your roof. If you live in a newer house, it may have had insulating panels inserted between its cavity walls when it was built - but this is less likely in older properties.

Cavity walls can be insulated - the insulating material is blown through holes drilled in the outside wall. However, this is really a job for a professional. You can insulate solid walls by dry-lining them - in other words, by adding an extra layer of plasterboard to their inner faces. Plasterboard with thermal and acoustic properties is ideal for this.

As it's up to 50mm thick, it's worth noting that the plasterboard will also reduce your room space by this amount. Fitting it isn't too difficult: you simply cut it to size, and then glue or screw it to the existing wall. But when you do this, you may have to move and reinstall electrical wiring, sockets and switches, radiators, doors, and windows.

4. How to insulate your floors

The floors in new houses have to be insulated. But in existing uninsulated floors, a good-quality carpet combined with underlay is often enough to minimise downward heat loss.

You can fill any gaps below your skirtings with flexible sealant, or cover them with wooden beading pinned to the skirting. Alternatively, you can lift the floorboards of a suspended floor and lay blanket or sheet insulation between the joists. If you have a concrete floor, you can build an insulated suspended floor on top of it.

5. How to soundproof your home