Your home's performance is dependent on the quality of its insulation and ventilation. Huge amounts of energy are lost through poor insulation. This wastes fuel, damages the environment and costs you money. New building regulations require owners to improve insulation, ventilation and soundproofing when carrying out alterations and renovations.

Home Insulation

Improving your home's insulation is one of the best overall investments of time and money you can make. Although the initial financial outlay may be quite high, the long-term savings on heating bills will make it worthwhile. You can insulate most parts of your home against heat loss, and even fairly modest measures can make a considerable difference. However, efficient thermal insulation must always go hand in hand with effective ventilation to prevent the buildup of condensation.

How Insulation Works

Heat flows from warm areas to cold areas, and moves in any direction. In the home, warm air expands and circulates, escaping through walls, ceilings, roofs, windows, doors, fireplaces and anywhere plumbing, ducting, or electrical wiring penetrates exterior walls. Thermal insulation acts as a barrier, reducing the amount of heat that escapes.

The term "U-value" is used when discussing thermal requirements in a house, especially in conjunction with insulation products. The aim is to achieve low U-values: this means that a house’s insulation is efficient. In a new-build home U-values are governed by building regulations, and the type of insulation used will therefore need to meet certain requirements.

Where to Insulate

Insulating the walls, attic, floors and windows of your home is the most effective way of reducing overall heat loss. However, there are many other parts of a home in which a few inexpensive and straightforward methods can make a dramatic improvement.

If you have a cold-water tank in your attic, make sure that you buy a cover for it, or that you cover it with blanket insulation. To avoid possible water contamination, install a secure seal underneath the insulation. You should also insulate any exposed attic pipes.

Modern hot-water cylinders are usually sold with a layer of insulation pre-fitted. If yours does not have this, buy a cover and fit it over the cylinder.

You should cover any attic traps with a layer of insulation, otherwise all your efforts to insulate your attic or roof space may be undermined by leakage through the hatch or around its edges.
Heat emitted by the rear of a radiator can be lost into or through the wall it is attached to. In the past, it was common practice to fit aluminum foil behind a radiator to reflect its heat back into the room, but now it is possible to buy purpose-made insulating kits to do this job.
Gaps between baseboards and floorboards can cause unpleasant drafts, and those drafts will lead to heat loss from your home. To avoid this, you can use filler or wood moldings to close up any gaps.

Thermal Image of Heat Loss
On a thermal image of a house, the roof shows up as cool and blue, suggesting there is insulation present, but the red windows and wooden slats show heat escaping. Even if you have good loft insulation it is important to consider other areas such as walls and windows. If you are fitting new windows in your home, they must have double-glazed units.

Insulating and Soundproofing Materials

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When choosing insulation, take into account the material's cost, ease of use, suitability to your needs and thermal properties (U-value). Bear in mind that greener materials are increasingly being used in this area. The effectiveness of a soundproofing material is based on what it is made of and how and where it is installed.

Blanket Insulation
Versatile and easy-to-use, rolls are usually the same width as the space between joists or rafters.

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Framefoil
Retards heat transfer by reflecting heat back to its source and by trapping air in its multiple layers.

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6 mil Polyethylene
This waterproof, clear polythene membrane is suitable for use below new concrete or wood floors.

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4 mil Polyethylene This polythene sheet plastic is used to stop water vapor from penetrating ceilings and sometimes walls.

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Cellulose
Requires a blower, which can be rented. Ideal for small spaces.

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Pipe Insulation Use this in a cold roof to prevent pipes from freezing, which may cause costly leaks and damage.

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Pipe Lagging
Use to wrap around attic water pipes.

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Flanking Tape
Use to cover gaps along edges when soundproofing.

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Acoustic Underlayment
Used under flooring instead of regular underlayment, this helps to improve a room’s sound insulation.

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Polystyrene Board
A rigid board installed below floors but also in roofs for insulation. Adjacent edges interlock using a tongue-and-groove design.

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Extruded Polystyrene Board
A rigid board used to insulate concrete floors. It is also bonded under flooring sheets to make storage decking in an attic.

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Rigid Board Insulation
This comes in panels and provides a high level of insulation. It is more expensive than blanket or loose-fill insulation.

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Acoustic Mat
Used in a continuous layer below flooring, this densely packed material reduces the effects of airborne noise.

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Acoustic Slab
This dense soundproofing material is sold in slabs. It can be laid below floors, above ceilings, and within walls.

Courtesy of DK - Do It Yourself Home Improvement © 2009 Dorling Kindersley Limited