Now you’ve probably heard of condensation and almost everyone likely knows what it means, but how many of you out there have heard of interstitial condensation? For those of you who haven’t let me explain what interstitial condensation exactly is.
Interstitial condensation is a form of damp that occurs when warm moist air from inside a structure, moves into a wall and reaches the dew point and condenses within the core of the wall to form water. Interstitial condensation can penetrate the walls, floors and ceilings of a structure.
Now I know what you’re thinking – this sounds like surface condensation and while the two are similar they are some differences. Interstitial condensation is when the condensation is formed in the core of the structure, while surface condensation is formed on the inside surface of the wall or roof.
Interstitial condensation can cause a number of serious issues like mould growth, timber rotting and can even cause the corrosion of metal re-inforcement within the core of a structure. It will also be a contributory factor to increasing condensation on the surface of the external walls. And like other forms of damp you may be unable to spot the problem before significant damage is done.
One noticeable problem to look out for is freezing. This occurs when the water droplets formed by Interstitial condensation freeze and expand thereby damaging the masonry. If this happens it will most likely cause some structural damage.
How do I stop Interstitial Condensation?
Interstitial condensation is a tricky form of damp to tackle because you likely won’t notice it till a lot of damage has been done. Costing great expense to repair, the best option all round is to try and take measures to prevent interstitial condensation from occurring in the first place.
You can prevent interstitial condensation from occurring by controlling the indoor moisture at its most common sources. This can be done in many ways – for example you could use dehumidifiers or install fans and air vents in particularly humid areas.
Vapour barriers are a way of preventing interstitial condensation from occurring, but they must be used in a certain way. The vapour barriers should be inside the structure in a heated building and be outside the structure on a cooled building.
Ironically, interstitial condensation is a more common issue in more modern structures that have been built to be both warm and cool. Older structures generally have better ventilation as they were built with more permeable materials and have lots of natural draughts and ventilation through chimneys for example.