Rising Damp - How is it found and what is it?

RISING DAMP DIAGNOSIS TECHNIQUES

Visual Inspection

• All other possible causes of dampness must be ruled out. Look for common causes of damp, such as faulty guttering and cracked rendering.

• If other faults are found, they should be fixed.

On Site Measurement Electric Moisture Meters

• Electric moisture meters (EMMs) are quick and easy to use and should be fully understood by the operator.

• Accurate readings from EMMs can only be achieved on timber.

• On surfaces other than timber, EMMs can be used to build up a pattern of moisture levels over a particular wall.

• EMMs should not be used to check the operation of a new damp proof course.

Calcium Carbide Meters

• Calcium carbide, or ‘Speedy’ meters can be used on site or in a laboratory.

• They can accurately determine the total volume of moisture in a sample taken from a wall, but cannot differentiate between rising damp and moisture due to the presence of ground salts.

Laboratory Analysis

• Laboratory analysis can accurately determine the volume of water present in a sample of wall material and whether this is from ground salts or rising damp.

• Laboratory analysis is relatively expensive, but produces the most accurate results.

Moisture Profiling

• Moisture profiling involves taking a series of vertical samples in order to establish the distribution of moisture and salts. This can be useful in historic or sensitive buildings, or where there is doubt over a diagnosis of rising damp.

WHAT IS RISING DAMP?

• Rising damp is water from the ground drawn up by capillary action – much as water is drawn into a tissue.

• Building materials are porous, moisture from the ground can rise into the building, unless there is a barrier to prevent it.

• Rising damp often appears as dampness on a ground floor wall, from the floor to a maximum height of 1.5 m.

• A tidemark may be evident at the top of the profile due to evaporating ground water salts.

• Salts will remain present long after a rising damp problem has been resolved, unless the wall is resurfaced with salt resistant render.

• There are many different causes of dampness in buildings, so investigations into possible rising damp must be undertaken by a trained and competent surveyor, such as one who holds the CSRT (Certificated Surveyor in Remedial Treatment) qualification.

If you would like to find out more about Rising Damp please check out Cheshire Remedial or have a look at the Property Care Association.