What is Dampness

In many situations the professional investigating the dampness will need an indication of the actual level of moisture within the structure. There is often a perceived need to know when a material is what might be called, dry. Although in absolute terms a porous material in a building will always retain some moisture, either from its own natural properties for example, hygroscopic or from the effects of water absorbing deliquescent salts.

Even in a normal dry building there is always a surprising amount of water present in porous materials, most of which does no harm. Although the amount varies widely depending on the nature of the material and on the humidity of the surrounding air. The following figures indicate the range that may be expected in some common materials;

• Plaster 0.2 – 1.0% wet weight
• Lightweight concrete >5%
• Timber10 – 20%

These amounts of moisture do little harm to the materials and such moisture is not usually regarded as dampness. That term is commonly reserved for conditions under which moisture is present in sufficient quantity either to become directly perceptible to sight or touch or to cause deterioration in the decorations and eventually in the fabric of the building.

A building is considered to be damp only if the moisture becomes visible through discolouration and staining of finishes or causes mould growth on surfaces, sulphate attack or frost damage or even drips or puddles. All of these signs confirm that other damage may be occurring.

Types of Dampness

A high proportion of dampness problems turn out to be one of the big three:

• Condensation
• Rising damp
• Rain penetration

Areas covered Dorset – Bournemouth – Poole – Weymouth - Christchurch – Ringwood – Wimborne – Ferndown – Corfe Mullen – Parkstone – Dorchester – Shaftesbury – Blandford - Westbourne – Wareham – Oakdale – Maiden Newton – Bridport – Yeovil – Warminster – Gillingham – Mere – Sturminster Newton – Salisbury – Southampton – New Forest – Fordingbridge – Wiltshire - Hampshire