Insulating Your Home

Minimal skills are needed. Follow the fixing instructions provided by the manufacturer of the product you are using.

When working in a dusty loft space, wear protective clothing - overalls, gloves, eye protectors and face mask. Lay planks across the joists to make a safe walkway.

When you insulate your home, you reduce the rate at which heat is lost through the roof, walls, floors, windows and doors. Less heat has to be produced to keep rooms at the required temperature, heating bills will be reduced and you will conserve energy. It is easy to see the dramatic reductions in heat loss that can be made by insulation.

Draughtproofing doors and windows not only saves money but makes your home much more comfortable too. The minimum recommended level of insulation thickness for lofts is 200mm (8in), but it is common to find as little as 25mm (1in) laid between the joists on the loft floor. Existing insulation can be topped-up to give a greater thickness. Although it may appear expensive to insulate your home to this degree, eventually the money you spend on insulation materials will be recovered in savings on your heating bills, and everything saved after that will be complete profit.

Insulating Your Loft

The loft Heat rises, and a lot of it is lost through the roof. Without doubt, the best place to start is with the loft. With a payback period of two years or less, if you are starting from a position of having no insulation at all, you will soon be saving a lot of money.

Insulating a loft, especially in an old house, is a really dusty job so you should equip yourself with safety clothing - overalls, gloves, eye protectors and face mask. Even if your loft is clean, you will still need protection when handling glass-fibre as it can cause skin irritation.

There are two ways to insulate loft floors - using blanket or loose-lay material.

The recommended thickness of insulation is 200mm (8in) but you may have to use 100mm (4in) if that is the height of your joists and you intend to board over the loft. Alternatively, build up the joists with strips of wood.

Blanket insulation is unrolled between the joists. It comes in two widths - 370mm (15in), which matches the joist spacing in older houses, and 600mm (24in) for more modern houses. It is in thicknesses of 100mm, 150mm and 200mm (4in, 6in and 8in).

Start at one side of the loft and unroll the material, working towards the middle. Tuck the end of the roll down into the eaves - but don't completely block them as it is important to get some ventilation into the loft to prevent condensation. As the loft will now be colder, warm, moist air from inside the house will condense on the cold roof timbers. If you prefer, fit eaves' ventilators to ensure an air flow.

Make sure you have light up in the loft while you are working - if there isn't a permanent light up there then get an extension cable and a lamp, or a large torch. Stand only on the joists, never between them, or you are likely to put your foot through the ceiling. Provide a series of boards to tread on, each one spanning at least three joists.

When you reach the middle, cut the insulation, go to the other end of the loft and start again, butting up the meeting edges in the middle. Repeat for each joist space. Tuck the blanket under electric wiring to avoid the risk of overheating.

Loose-fill fibre comes in bags which are tipped out between the joists and levelled off with the tops of the joists using a piece of hardboard.

It needs no cutting or fitting and is easier to use in lofts where the joist spacing is not of a standard size. It is also ideal for topping-up existing insulation of any kind.

Insulate the loft hatch by fixing a glass-fibre blanket to it. To keep the blanket in place, tap nails into each corner of the hatch and criss-cross string between them. In confined roofs, the spaces in between the rafters can be insulated with expanded-polystyrene boards which are compressed and squeezed into the spaces. They are suitable for spacings of 320mm to 395mm (13in to 16in).

Insulating Your Plumbing

A good starting point is the hot-water cylinder. An 80mm (3in) thick insulating jacket (BS 5615) is cheap, will pay for itself in a year and is easy to fit - you just strap it to the cylinder. If the cylinder already has a thin jacket, then simply place the thicker one over the top.

Insulating hot-water pipes will reduce the waiting time for hot water to flow from a tap. The most important pipes to lag are under the floor and in the loft. Insulate the pipe running from the boiler to the hot-water cylinder too.

You must also insulate cold-water pipes in the loft, the cold-water cistern and the small feed and expansion tank (if there is one). The cistern can be wrapped in a purpose-made jacket or lagged with a glass-fibre blanket.

All pipework can be lagged with split foam tubes which simply slip around the pipes. Use a double thickness at bends where freeze-ups are most likely. Tape or clip the tubes at intervals to keep them closed.

The stopcock is often left unprotected but covers are available and can be fitted in minutes.

If you insulate the loft floor, don't cover the area below the cistern - any heat rising from the room below will help prevent the tank freezing.


Draught excluders reduce fuel bills and make your home more comfortable. You should fit draught excluders to all gaps around doors and windows. There's a wide variety of excluders available, ranging from simple-to-fit foam self-adhesive strips to more sophisticated and durable EPDM seals. There are also complete door sets for external and internal doors.

Self-adhesive foam strips - economical and simple to fix in place.
V-shaped strips - best used for uneven or large gaps. Sprung strip is pinned to the rebates of the door frame.
Rigid strips with rubber seal - for larger or uneven gaps.
EPDM seals - better for larger gaps.

Draught strips and door excluders come in brown, white, wood and gold effect.

To work out the thickness of the gap you need to fill, use this easy formula: 1p piece = 1.5mm, 2p piece = 2mm, 50p piece = 2.5mm and £1 coin = 3mm.

Apart from windows and doors, remember to fit escutcheons over keyholes and draught excluders over letter boxes.

If you get draughts coming in under doors, fit threshold excluders, either a rubber or a brush strip that come as a single piece.

With two-part excluders, one part is fixed to the door and the other to the threshold; when the door is closed, the two parts interlock to form a tight seal.

While draught excluders help to prevent warm air escaping, they also prevent fresh air from entering. If your home contains coal and gas fires (and other gas appliances without a balanced flue) they need a supply of fresh air to keep them working properly, and to control condensation. Introduce fresh air into the house through ventilators which can be properly controlled.

Insulating Your Walls

In an un-insulated house, the walls account for up to half of the total heat loss. Around 70% of this heat loss can be saved in a cavity wall in houses built before 1976. Professional installation is recommended for this form of insulation.

Older houses with solid walls can be drylined, adding an extra layer to the inner face of an outside wall. The layer is insulating plasterboard - ordinary plasterboard stuck to a backing of expanded polystyrene - and is up to 50mm (2in) thick so you will reduce your room by this amount.

Fitting the insulating plasterboard is not difficult - once you have cut it to size it can simply be glued and screwed into place on the existing wall. If the wall is plain, it's just a matter of removing the skirtings and picture rails, fixing the board and replacing the woodwork. However, where there are doors, windows, radiators, electric switches and sockets, these will have to be repositioned or modified to account for the new 50mm (2in) layer of plasterboard.


Line the walls behind radiators with special foil to deflect heat back into the room. The foil is cut to size just smaller than the radiator and is fixed to the wall using adhesive.

Insulating Your Floors

Even though heat can be lost through suspended ground floors (floorboards on joists), it is questionable whether it is worth the effort of insulating them - unless you are having to replace floorboards anyway. Usually a good quality carpet combined with underlay or other floorcovering laid on hardboard is sufficient to minimise downward heat loss.

Gaps below skirtings can be filled with mastic or covered with wooden beading, pinned to the skirting rather than the floor so the floor is allowed to move.

Never block up the air-bricks in outside walls. The airflow beneath a suspended wooden floor is essential to keep the wood dry and free from rot.

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