Eco Home Insulation

In general terms, it’s worth remembering that in new home applications, your insulation material will play a huge role in ensuring your walls, floors and roofs meet the U-values required by the building regulations. Namely, all insulation materials will help you get to the same destination, just in different ways. So the less efficient your insulation, the bigger the thickness you’ll need – and this is, of course, a major issue for retrofit situations.

So what are your options?

Types of Insulation

Mineral Wool and Fibreglass Insulation

When people think of insulation, this is probably what they think of – it’s the stuff you can pick up in rolls in the major DIY retailers and is the most common form of insulation used. Not entirely coincidentally it’s also the cheapest to purchase. It works very well as an insulator when laid flat in lofts, and although it will sag over time (which is why your loft insulation needs re-doing every decade or so) it can be ‘wicked’ (rhymes with ‘licked’) to give it a bit of rigidity. These batts are often used in cavity walls. The main manufacturer in the field is Rockwool.

While the wools are the cheapest form of insulation, they do require significant thicknesses in order to achieve desired U-values.

Polyurethane Insulation (also Phenolic Foam and Polyisocyanurate Foam)

These are the rigid, foil-backed boards that tend to go by the trade names of Kingspan and Celotex. Boards of this sort are highly efficient – and as a result can achieve the required U-values on a much lower thickness than the wools.

Expanded Polystyrene

Supplied in either rigid boards or blown in bead form into existing cavity walls, expanded polystyrene – the best-known supplier of which being Jablite – is a good value insulator and performs similarly to the wools. It is commonly used as a floor insulation and where a cavity is partially filled. Also known as EPS.

Extruded Polystyrene

Best known as Styrofoam or Polyfoam, this form of polystyrene insulation is best used for floors. It’s denser and stronger than EPS.

Eco Home Insulation

Sheeps Wool Insulation

This is, of course, the original insulation material. Sheep’s wool is a pretty expensive alternative to the wools but it is much nicer to work with (fibreglass in particular is itchy). The best known UK supplier is Second Nature, whose product is known as Thermafleece.

Cellulose Fibre

This is formed from recycled newspapers and has to be blown in as it is not available in sheet form. The main UK product is known as Warmcel.

Cavity Wall Insulation

Since the 1920s most homes built in the UK were built with a cavity – a gap between two leaves of blockwork (or blockwork and brick). However, it was only until the 1970s that some housebuilders began to fill this cavity with insulation, and it only became compulsory in the 1990s to do so.

According to the Energy Saving Trust, at least one third of all heat lost in a home is lost through uininsulated walls, and as a result, those with uninsulated cavity walls can enjoy significant energy-saving benefits by insulating their cavities.

Insulating a cavity wall costs around £250. The process consists of injecting (or blowing in) a wool, EPS bead or foam insulation through 2.5cm diameter injection holes.

It’s important that the job is done properly, particularly to ensure that cavity barriers are inserted and ventilation to the property is maintained. Check out CIGA for a list of suppliers in your area.

Solid Wall Insulation

According to David Olivier of Energy Advisory Associates, H&R’s energy specialist, the first thing to look at is external insulation. “It is much more durable than internal insulation, keeps the walls extremely warm and you do not use up valuable living space as you can easily do installing internal insulation,” he says. With houses that are clad with weatherboard, hanging tiles or a render, he recommends removing the outer covering, installing insulation in the form of rigid batts or boards, then replacing the cladding.

When this is not feasible, or is unacceptable from a visual point of view, most architects would recommend a standard dry lining system from one of the ‘Big Three’: British Gypsum, Lafarge or Knauf. However, the answer is often not that simple, because this might well ignore the nature of the building. If, for example, it is a conversion project and the walls are of high quality, the last thing many renovators want is to lose the building’s character. In any case, should the building be listed or in a conservation area, the owner might well be required not to interfere with the appearance of the outer walls. To conform to current insulation requirements it might therefore be necessary to add insulation in other parts of the building, such as the floors and roof.

Standard dry lining systems will not always suit barn walls or the walls of old buildings that have very irregular walls. To get further insulation into walls like this you may well need to install your own system using timber studs from floor to ceiling with rigid insulation behind. The controversy will always rage on whether these materials will allow breathability in the same way as sheep’s wool or other natural insulation products. They do, however, have the advantage of compactness, though if you choose to use a board material like Kingspan’s Kooltherm or Celotex double-R, you will pay more than using mineral fibre.

One advantage of a ‘DIY’ system is that it should be sufficiently adaptable to be used in one section of a building and not another, so that where you choose to retain the inside of the original walls in full view internally, you can do so. The only problem of an approach like this, where the stud partitioning does not cover all the external walls, is that you may encounter problems in concealing services.

Further Reading

• Installing Loft Insulation
• How to Insulate Old Houses
• Solutions for Insulating Walls