September to April is regarded as the condensation season, condensation and mould related problems are a very common problem that seem to go on and on in some properties, most of the problems I come across during my surveys are simple to fix with some basic tips. Condensation is best tackled at source, this is the moisture producing areas-the kitchen and bathroom, a decent humidistat extraction fan is a must. An extraction fan will not cure all the problems if there is no heating, a balance of heating and ventilation is required, sometimes this is the hardest part trying to explain to somebody that is suffering from fuel poverty that a certain amount of heating is required. Positive input ventilation (PIV) will also not cure condensation if the building isn’t adequately heated.
What does a condensation survey consist of?
A visual survey of the internal and the external areas in question. You also need some basic kit, hygrometer, infra red spot laser measurer, this can then measure the relative humidity, vapour pressure, air temperature and dew point. This can on most surveys along with an external and internal survey of the property give you an answer, sometimes though you need to got that little bit further, good diagnosis is the key to solving a problem.
Measuring extraction fan airflow
Measuring the extraction fan speed by means of an anemometer, this tells us the litres per second and if the fan is up to the job in question.
Thermal imaging for condensation
Thermal imaging plays the biggest role in my surveys along with my Flir MR77 meter as I can see exactly what the temperature difference is on all the building fabric, ranging from the floors, walls ceilings. A building with a cavity wall may need a small hole drilled in the outer skin to observe what is happening in the wall, is there mortar causing a cold bridge, insulation present, what type, is it wet or even vermin nest. A surveyor must sometimes have a good idea of building construction and be suitably experienced to diagnose condensation and mould related problems. Where there is a long term problem and a dispute between the landlord and tenant, data logging of the internal environment can give conclusive answers in visual graphs, showing what time there was high humidity and at what temperature the area was and showing the dew point. Thermal imaging for condensation and mould related issues is great, it gives me the chance to show my client exactly what the problem is visually. If you look at the thermal images below that have been created in my Flir software program, it shows the importance of temperature differences. A couple of degrees difference is enough for a condensation problem to occur.
The above condensation problem has been caused by the installation of a passifier vent, this was installed at the wrong height. It was actually installed to cure condensation in other parts of the property. The main problem with the installation is that it was not sleeved through the cavity, so what happened was the cold wind was blown into the cavity making the internal skin cold which then resulted in the mould and condensation problem.
The above problem on this wall as you can see has thick black mould all over it. You can see in the thermal imaging picture where the coldest area is, the cause of the problem was penetrating damp from the coping stones, the walls are now wet and are obviously cold which resulted in condensation and mould related issues.
The above picture shows a very common condensation and mould problem on a cold timber door. Look at the temperature differences showing the coldest spots and the warmer spots, you can see just a couple of degrees difference is enough for condensation to occur.
The above picture shows condensation occurring on a corner of an external wall which is north facing (a cold wall). Note SP6 and SP7 are on a thermal board and there is no condensation occurring, again a couple of degrees difference, which is enough to keep condensation and mould problems away.
The above problem shows a cold spot on the corner of an external wall.
The above thermal image shows condensation occurring at low level, this is actually adjacent to a Chapel of rest, which is obviously cold. This caused a fungal decay problem that was mis-diagnosed as rising damp, when it was a condensation problem.
The above pictures show how serious things can get if the problem is left to manifest.
Data logging for condensation and mould problems
Data logging is very important, most condensation surveys are a snap shot in time. It is sometimes necessary when there has been a long term problem and there is a dispute. This paints a picture of what is really going on, and is normally used in disputes for Housing Associations.
See the visual graphs showing what is actually happening every 30 minutes. I must emphasise that simply using an internal data logger isn’t really good enough, you will also need surface temperature measurement to show when a wall is below dew point (condensation) and an external data logger so you can show the differential vapour pressure, all of this is then put into a specialist Excel spreadsheet to produce our graphs.
I have been trained by the Property Care Association www.propertycare-org on condensation issues and I have also completed the Condensation And Moisture Management Master Class, along with being a Certified Level 1 Thermographer.
Contact Complete preservation for a condensation survey 01225 76925
I was fortunate to be personally trained by my friend Graham Coleman who is regarded as the “Expert” in dampness and timber problems. You can contact him direct for data logging and thermal imaging surveys www.buildingpreservation.com
Another expert in this area is another friend of mine, Bryan Hindle from Brick Tie Preservation. Bryan also offers data logging and thermal imaging surveys www.btpreservation.co.uk