We often hear claims about external wall insulation that are completely untrue so we thought we’d round them up to prove why we believe in it so strongly as an energy saving measure.

  1. External wall insulation stops buildings being able to breathe

It’s certainly true that houses need a good air flow to make sure that fresh air is supplied to residents and moisture and emissions can escape.

Our external wall insulation products don’t stop this circulation of air.

Obviously, you’ll still need to ensure adequate ventilation through opening windows and using fans when necessary in steamy rooms such as bathrooms and kitchens.

2. External wall insulation leads to mould

Kind of the opposite -Mould occurs from damp, often caused when warm, moist air in a room cools on walls and ceilings, causing condensation to form. EWI raises the surface temperature of walls, reducing the temperature difference between the inside and outside and meaning condensation is less likely to settle on walls.

Plus, as mentioned above, our renders are breathable and therefore discourage the buildup of damp. Also, our mechanical fixings are designed with plastic, to keep thermal bridging to a minimum.

So there’s no reason why external wall insulation would cause mould, as long as you take the normal precautions. As always, it’s important to ensure adequate ventilation through opening windows and using extractor fans in areas of the home where steam is present, such as kitchens and bathrooms.

3. It uses more energy to manufacture external wall insulation than the measure saves over its lifetime

This is categorically untrue. While there’s no denying the energy used in manufacturing chemical-bases insulation products such as XPS, the payback in terms of the energy you save through installing them makes it worthwhile in almost all cases. The manufacture of foam, glass, PU or XPS insulation is estimated at 1,3000kWh/m3. Based on these figures, the payback in terms of energy saved can be as little as 1-2 years.

For example, 90mm of EPS attached to a traditional 9-inch solid brick wall will reduce the U-value (which is a measure of how much energy is lost) from 2.2 down to just 0.3 per m2K, bringing it in line with a brand new wall built today. Even with the most expensive insulating materials installed at a high thickness, the energy amortisation period will generally be less than 5 years. 

4. External wall insulation is a fire hazard

All our insulation materials are fire retardant, especially Rockwool, which has unrivalled fire resistance.

5. External wall insulation can damage health

None of our insulation materials contain fibres hazardous to health as they come in solid blocks. They are also sealed with an impermeable coat of render.

6. External wall insulation encourages the growth of algae

While normally only a cosmetic problem, algae growing on walls can be an annoyance to the homeowner.

Our renders are hydrophobic, meaning they repel water and are resistant to the growth of vegetation. They’ll keep your home looking new – probably more so than standard brick.

7. A living roof will insulate just as well

Green roofs and walls, planted with grasses and flowers, have a minimal effect on heat transfer through solid surfaces. Although living roofs can help with air pollution in densely populated areas, the only way they affect temperature is that they can help keep walls cool in summer, because sunlight cannot shine directly on the facade.

Conversely, external wall insulation has an impact in both summer and winter – and a much bigger one at that. It can prevent up to 40% of heat lost from a property.

8. External wall insulation looks ugly

EWI can actually really smarten and brighten a property, as well as protecting brickwork underneath. Render, as the final stage of external wall insulation, can be chosen in a variety of colours and even covered in realistic brick slips if you would like to recreate period features.

We hope we’ve cleared a few things up about external wall insulation. If you think of any questions we haven’t answered, let us know!

If you’re interested in getting a quote for external wall insulation, fill in the form below:

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