As condensation is a form of damp, finding the source or cause of the moisture is the most important point to treat the ongoing issue. However, there are several types of condensation which can occur within your property and I have identified these below including how each type can be diagnosed.
Cold-bridge condensation occurs when warm moisture air makes contact with internal surfaces, which are colder (equal to or below its dew point). This is caused by an element in the structure or fabric of the building being allowing coldness to pass through from the external surface to the internal finishes. This is most often caused by the lack of a insulation break between the external face of the building and internal surface (such as around windows and doors). When the warm moist air is produced in the building and it touches these colder elements, this is known as Cold Bridging.
If you are diagnosing this form of condensation, examples of this process include condensation at the base of external walls, condensation on window panes where evidence of decay to the timber frames is apparent, and condensation forming on the undersides of roof surfaces. This form of condensation can also be found when different types of damp are visible such as penetrating damp into structures, as this will usually degrade the insulating properties of the element and therefore form a ‘cold bridge‘, which completes the vicious circle resulting in further condensation. If you have noticed deterioration to timber window frames and/or door surrounds with evidence of flaking paint finishes, or water run-off marks to window and door jambs, which are both key indicators that your damp issue is cold-bridge condensation.
Older readers may remember frost appearing on the inside of windows, but in today’s central heated buildings, the ‘frost’ is now more likely represented in condensation forming and shows a lack of thermal insulation in the window panes, more commonly remedied by installing new double or triple glazed windows.
As mentioned above, cold bridging is more likely to occur on saturated surfaces, as wet surfaces as less thermally efficient. If you have a leak in your property, these areas are more likely to be colder and thus allow cold bridging to occur more readily. You will therefore need to ensure that any leaking gutters, downpipes, heating and water pipes and the like in the area are repaired before being able to treat the ‘cold spot’.
Interstitial condensation can be found in all buildings and can occur when warm moist air diffuses into a moisture-permeable material, usually fibrous wool insulation which is generally used in insulating walls and loft spaces. If one side of the insulation is colder than the other the moisture will continue through the porous material until it reaches a surface cold enough to condense, this is the point where the water vapour will condense to a liquid form and start to deteriorated the building materials. Of course, where condensation forms on the insulating materials it dampens it, reducing its thermal properties, allowing the colder surfaces and condensation formation to creep ever inward, thus being a degenerative defect.
The key indicator of interstitial condensation is mould growth to the wall surface, although the same defect occurs when other types of condensation are apparent the best way diagnose this form of condensation is to focus of the mould pattern. This form of mould can be distinguished by being over an entire surface instead of confined to a corner of the room or a particular area.
Now you can diagnose the different forms of condensation within your building, the final and most important part is the treatment methods. For those of you who don’t currently have a condensation issue but are worried about condensation occurring within your property, we will also detail the prevention methods which can be implemented to ensure this defect does not affect your home.
This form of condensation generally occurs in cold unoccupied buildings within the UK, the process occurs when warm moist air ‘warm front’, arrives from the Atlantic during the winter months and enters cold unheated buildings. This causes condensed water to run down the surfaces of the internal walls and windows which can lead to deterioration of the internal finishes, fungal growth, wet and dry rot. If these issues are left untreated for prolonged periods of time the damage caused to the building can be catastrophic, resulting in major structural issues and expensive remedial works required.
If you have a building which is currently unheated and unoccupied, you may have notice black mould growth and water staining to the interior surface of the external walls. The mold will form on the wall surfaces, generally at lower level where the water droplets have saturated the material finish.