We are often asked about condensation, particularly from people who have experienced ownership of single skin metal or plastic sheds or concrete sheds. Condensation in wooden sheds is not so visible as it is contained within the wood, but it is still there. This type of condensation is called interstitial condensation and can be identified by the damp environment and musty smell giving evidence of the wood slowly rotting.
What is condensation?
Warm air can hold more moisture than cold air, when the two meet and reach the saturation point precipitation takes place and falls as rain. When warm, moist air meets a cold surface (known as the cold barrier) precipitation takes place in the form of condensation.
All buildings, sheds, garages and houses, can suffer from condensation.
What can be done to stop condensation?
Condensation is a basic law of physics. It cannot be stopped, but measures can be taken to help prevent it forming on cold surfaces, these being ventilation and insulation.
Ventilation is the most important and efficient way to prevent condensation. Keeping the inside and outside temperatures the same removes the cold barrier and therefore removes the condensation surface.
Insulating between two surfaces exposed to different air temperatures can reduce or prevent condensation. Examples of this are double glazing and insulated building blocks. Insulation without ventilation can still promote condensation.
De-humidifiers can remove moisture from the air but require a sealed environment to be effective. They are costly to run and require daily maintenance. For these reasons de-humidifiers are not suitable for sheds or garages.
DaylightSECURE sheds tackle the condensation problem in three ways:
1) TPR has a low thermal conductivity of just 0.174 W/mK and is non-porous. Walls have a minimum thickness of 25mm creating an environment for the inner and outer surfaces to have different temperatures. Air on the outside of the shed walls will control the temperature of the outer panel surface and air on the inside of the shed will control the temperature of the inner panel surface. The two temperatures do not meet preventing the formation of a cold barrier.
2) The double skinned steel doors are insulated with a thick polyurethane core. The insulation removes the cold barrier which allows for temperature differentials between the air inside and the air outside.
3) The roof is a single skin and therefore more susceptible to condensation. To combat the risk all DaylightSECURE sheds are designed to provide maximum airflow across the roof through vents positioned at the top of each corner under the eaves of the roof. Air is drawn from the outside and passes through the top vents creating a natural airflow across the inside surface of the roof. The drawn air helps to keep the roof at the same temperature as the outside air to remove the cold barrier. It is important that airflow through the vents is not blocked or obstructed by fences, hedges or walls higher than the level of the roof vents.
Although DaylightSecure sheds offer better protection against condensation than sheds built from steel, plastic or wood it is still possible for condensation to form on the roof given the right atmospheric conditions (warm air with high humidity followed by a cold temperature and still wind). In the first five years of selling DaylightSECURE sheds only three cases of condensation have been reported, two of these were positioned with restricted airflow. If the shed has to be positioned where air flow is restricted, we recommend fitting a fan as a precautionary measure.
A fan, drawing air from outside the shed, will equalise the inside and outside temperatures when there is not sufficient wind to produce airflow through the shed. A fan will also prevent sheds from getting too hot in the summer sun and will accelerate drying any items that are wet when stored in the shed.
Brodco can supply both mains and solar powered fans that provide a 24/7 airflow of 2 cubic metres a minute through the shed as an optional extra.