Flood Damage Building Drying

The drying of flood damaged buildings doesn’t have to take an age. Desiccant dehumidification is the key

Engineered for efficiency, built to last.

Drying buildings following flood and water damage

A major setback in the restoration process is the time taken to dry out buildings, prior to starting remedial building work. There are potentially hundreds of litres of water that remain hidden within the building’s structure.

As a result, buildings remain unfit for use or occupation for many months, during which time high internal humidity levels can cause secondary damage and increase the risk of dangerous mould growths.

Whilst the drying rate of a material will vary according to its porosity and density, it is also determined by the ability of moisture to evaporate into the surrounding air.

Drying rates are greatly improved by lowering relative humidity, adding heat and increasing air movement.

Ideal drying conditions of 35 to 55 %RH can only be maintained if the dehumidifier capacity is greater than the rate at which moisture is being evaporated.

If the internal relative humidity rises uncontrollably (e.g., condensation on external walls and windows) it is a clear indication that the dehumidifier capacity is too small.

Why choose desiccant dehumidifiers to dry out flood damaged buildings?

The majority of flood damage within the UK occurs in the colder months of the year. Many homeowners are often left wondering why the traditional refrigerant type building driers take so long to remove the moisture from the building following flooding.

The answer is very simple, refrigerant type (condensation type) dehumidifiers are not suitable for operation at low temperatures due to the nature of how they work.

In many cases, below 10.0°Cdb a condensing type of dehumidifier, will remove little moisture as this sits below their efficient operating parameters.

DT MDC450 Rental Dehumidifier
DT MDC450 Rental Dehumidifier

Comparison between desiccant and condensing type dehumidifiers

How desiccant dehumidifiers work
How desiccant dehumidifiers work

Desiccant type dehumidifier


  • MDC300 Rental desiccant dehumidifier – 300 m³/h
  • Capacity at °Cdb / Relative Humidity (RH)
  • 30/80 = 40.8 Litres per day
  • 30/60 = 36 Litres per day
  • 20/60 = 33.6 Litres per day
  • 10/60 = 28.8 Litres per day
  • 5/60 = 19.2 Litres per day
How Condensing type dehumidifiers work

Condensing type dehumidifier


  • Generic Condensing type building rental dryer – 450 m³/h
  • Capacity at °Cdb / Relative Humidity (RH)
  • 30/80 = 49 Litres per day
  • 30/60 = 32 Litres per day
  • 20/60 = 16.5 Litres per day
  • 10/60 = 10.2 Litres per day
  • 5/60 = <5 Litres per day

Desiccant technology is the best choice for drying flood and water damaged buildings.

From the examples above, it is clear that whilst condensing type dehumidifiers have a high removal capacity and efficiency when both the temperature and relative humidity is high, they rapidly lose capacity as the ambient temperature drops.

During periods of even moderate temperatures, desiccant dehumidifiers will constantly out perform the condensing type. Below 15.0°Cdb ambient, refrigeration type dehumidifiers will also require to undergo regular defrost cycles, whereas desiccant type will continually remove moisture even at temperatures below zero.