The benefits of proper insulation and ventilation


When DIYers or those with limited building experience try to improve the insulation of a home, they need to ensure that they do so in a way that will not create problems with condensation either within the structure of the building fabric (called interstitial condensation) or on the inside surfaces of rooms due to the unintentional creation of cold spots – called ‘thermal bridges’

Thermal bridging can be a particular problem for existing buildings. Making sure that there are no areas left uninsulated – such as under floor boards for example – is important as these will become cold when compared to the rest of the building and attract condensation and promote mould growth.

Seeking technical advice on the best way to insulate walls, floors or roofs is a great way to get the best result from any refurbishment or new build project as it ensure that the proposed solution delivers the appropriate U-value (a measure of heat loss through the construction) and has passed a condensation risk analysis. For new build projects a SAP or SBEM calculation, available through Energy Assessments by Saint-Gobain Interior Solutions brand Celotex, is carried out to assess performance of the whole building fabric.

The guidelines for the advice are taken from an Approved Document of the Building Regulations called Part L – The Conservation of Fuel and Power along with the appropriate British Standards relating to the control of condensation within buildings.

Another Approved Document – Part F, plays an important role as this addresses Ventilation. Good ventilation is key within buildings as it ensures that a good level of indoor air quality is maintained further reducing condensation risks and also helping to keep the home cool in the summer to prevent overheating.

Insulation often gets the blame for overheating however, insulation serves both purposes: it keeps the home warm by stopping heat from escaping, but it also keeps the home cool by preventing the heat getting in.

Recently built homes constructed to Building Regulations can suffer from overheating in the summer months and this is also the case with retrofit projects because frequently, a proper assessment of the existing insulation and ventilation measures isn’t completed and both strategies aren’t considered in unison.

Part L and Part F of the Building Regulations used to be revised at the same time to ensure that insulation and ventilation were on the same page. However, this has not happened in recent revisions, making it vital that an appropriate ventilation strategy for the designed footprint / layout of new build or refurbishment projects is carried out and implemented

Whether new build or refurbishment, what’s needed is a holistic approach. For example, on a retrofit project, a home might have double glazing to conserve heat and provide security, but do the windows also have a secure purge ventilation option for night cooling and are the homeowners aware of the solution and know how and when to use them?

Insulating properties without due consideration of condensation and ventilation issues can be damaging to the health and wellbeing of building users, but equally, if you insulate correctly, it will have a positive influence on those who use that space. To strike the balance, it’s all about understanding the relationship between insulation, condensation and ventilation, knowing what you’re starting with (on a refurbishment) and getting the right advice.