How thick should EWI be?
As a general rule, 100mm insulation boards are typically installed. Some EWI systems are manufactured to be thinner whist providing better U-value savings.
How effective is EWI?
The lower the U-value, the greater the resistance to heat loss and the less it will cost to heat the building. A solid brick wall will typically have a U-value of 2.0W/m²K and installing EWI can reduce this to 0.30W/m²K or better which could cut heating costs by up to 50%.
How effective is 50mm insulation?
With 50mm of insulation you should expect to see a reduction in your heating bills by around 30%, but with 100mm that percentage will shoot to over 50%. Your heating system won’t have to work as hard, and as a result won’t use as much gas – so more cash in your pocket!
Is 50mm insulation board enough?
You can use two sheets of 50mm but it is not enough to comply with current regulations. You will not achieve the correct “U Value” which is the thermal resistance. In a nutshell your roof could end up with condensation (interstitial). Ideally if using Celotex you need a minimum of 120mm.
Do you need planning permission for EWI?
EWI is considered ‘permitted development’ so typically does not require planning permission. However, if you live in a listed building or a conservation area then you may need planning permission to get EWI installed.
Is insulation worth the cost?
The short answer is that getting proper insulation is worth it – the cost of installation is low compared to the amount you will save in the long term. Insulation is generally low maintenance and lasts a life time. You lose 35% of heat through your walls if you don’t have adequate insulation.
Can I install external insulation myself?
External wall insulation is not normally installed by a homeowner or DIYer, but instead is generally undertaken by a professional due to the complex procedures involved. Additionally, external wall insulation will transform the appearance of your home, so in some cases planning permission may be required.
How long does external insulation take to install?
The work takes 2-4 weeks, depending on the size of your property and weather conditions. All work is carried out on the exterior of your building, so there is no disruption to your daily life inside your home.
How to know if standard EWI is fit for purpose?
There are millions of solid wall and non-traditional properties in the UK which suffer from poor thermal performance. If these are structurally sound and the substrate of sufficient quality then a direct EWI system may be all that is required. How do you know if standard EWI is fit for purpose?
Can a structherm be used as an EWI system?
Whilst Structherm are renown for their unique Structural External Wall Insulation System we recognise that such a system may be over engineered for many projects. Often, a standard EWI system may be all that is required.
How much EWI do you need for external wall insulation?
EWI is carried down to 300mm minimum below internal floor level to prevent cold bridging, but stopped short of external ground level. Detail for external wall insulation to below ground floor level, with a periscopic vent and air-brick installed through EWI to ventilate a basement or cellar.
Is there any information available about ewi in the UK?
There appears to be little existing information available aimed specifically at clients looking to implement EWI. The UK Green Building Council retrofit task group carried out a high level search of literature sources related to domestic refurbishment, including EWI. While numerous technical standards exist covering some very specific aspects of a