Does IWI make your house too airtight and can it be bad for your health? – CIJA? | Ep.49

One of the most common worries we hear about internal wall insulation is that it makes a house too airtight, leaving people feeling like they can’t breathe and creating unhealthy conditions inside. In this episode, Andy Banister and Chris Brookman, explains why that fear comes from mixing up two things that are actually separate: airtightness and ventilation.

Airtightness is about stopping uncontrolled air leaking through gaps in the building fabric, like the join between a window frame and the wall. Ventilation is the controlled fresh air you bring into a space, either by opening windows or through a mechanical system. You want high levels of both. A well sealed home with proper ventilation gives you better thermal comfort, good moisture control and lower energy bills, without any of the stuffiness people fear.

The key is making the insulation continuous. It needs to wrap around the whole interior rather than skipping the tricky spots like the kitchen or bathroom. Done properly, that continuous layer keeps all your internal surfaces warm, which is exactly what prevents the mould growth people often associate with insulation in the first place.

And it isn’t just a winter benefit. As Andy points out, an airtight fabric matters just as much in summer, helping keep homes comfortable through the kind of extreme heat we’ve been seeing more of.

Watch the video to hear the full breakdown.