Why is interstitial condensation problematic?

All interstitial condensation can cause uncontrolled mold and bacteria growth, rotting of wood components, corrosion of metal components and/or a reduction in the thermal insulation’s effectiveness.

How does interstitial condensation affect materials?

Interstitial condensation happens within the thickness of a building’s elements, for example inside the floors, walls or roof. The warm air vapour passes through the surface and cools down within the structure, leading to condensation which can result in the deterioration of the property fabric and structure.

How do I fix condensation in my ceiling?

Before you install more insulation, seal any air leaks that could let attic air flow to your ceiling. Apply rigid foam insulation to the top of the attic hatch and install weatherstripping on the edges of the hatch. Fill joist spaces with rolled-up insulation batts.

How do you fix interstitial condensation?

Another few methods to stop interstitial condensation is through vapour controlled layers positioned on the warm side of insulation, replacing old materials with newer materials designed specifically to resist condensation forming, ventilated cavities, and installing thermostat controlled heating to create a constant …

What can cause interstitial condensation on a roof?

Here are some things you can keep an eye out for so see if your home is potentially at risk of interstitial condensation in walls or roofs: Cold spots on walls, due to the reduced thermal efficiency of insulation that is saturated with moisture. Mold growth, which is a cause of respiratory allergies.

When does interstitial condensation occur in the air?

Condensation is the activity of water vapour held in the air being forced to condense from a gas to a liquid. It most commonly takes place when air with lots of warm moisture meets a cold surface, creating a reaction that forms either surface condensation or interstitial condensation.

How can condensation in roof spaces be controlled?

It recommends that with cold roof constructions (uninhabited, unheated loft spaces where the insulation is laid over a horizontal ceiling) there should be at least a 7mm continuous ventilation gap at the eaves when using a vapour permeable underlay with a normal unsealed ceiling. Good external air flow is also required for ventilation to work well.

How are buildings designed to prevent interstitial condensation?

Interstitial condensation tends to occur on the warm side of vapour resistant layers . To prevent this, buildings need to be designed so that the temperature profile across the construction remains higher than the dew point temperature: