It is essential when investigating the potential for rising damp problems to eliminate other sources of water ingress. A guide to the approach to be adopted for a damp survey is shown below. Care must be taken to eliminate other potential sources of moisture, especially condensation in the colder months, and it is therefore essential to ensure that a full investigation is always undertaken. If any other sources are identified then these must be first eliminated before a proper assessment of any rising dampness can be made as it can be very difficult to distinguish between two or more interfering sources of water ingress.
Should it be noted that previous damp-proofing works have been undertaken then it is essential to take great care ensuring that the evidence of dampness is correctly evaluated.
The following gives a guide to onsite routine procedures for the survey:
1. External Examination
- External rainwater goods, valleys, flat roofs.
- Condition of brickwork, stone, mortar, plinths, render, weatherproof finish, etc.
- Wall construction, cracks in masonry, copings, etc.
- External timbers including windows and doors.
- Air vents; their position and condition.
- Chimneys and flashings.
- Position of any remedial DPC installation including spacing and depth of holes where chemical systems have been used.
- High ground levels, abutting garden wall, steps and positions and intergrity of any DPC system.
2. Primary Internal Examination: Visable Signs
- Fungal decay in skirting and/or other timbers.
- Peeling / blistering wallpaper, peeling / blistering paintwork.
- Mould growth, staining.
- Damp / Wet patches, water droplets, water runs.
3. Secondary Examination: (assuming correct use of properly functioning and calibrated electrical moisture meter)
- Examine both perimeter and centre of solid / timber suspended floors.
- Check moisture content of timber skirting (top and base).
- Examine and check condition of the floor / wall junction, edge of DPM of floor.
- Check any remedial DPC installation including position and depth of holes (if inserted from inside).
- Note distribution of moisture meter readings both vertically and horizontally on the surface of walls.
- Check for efflorescence beneath wallpaper finishes.
- Note any use of polystyrene sheet / metal foil beneath wallpaper.
- Note any new plasterwork, height of replastering, its condition and if possible, its type e.g. renovating, sand / cement, lightweight premix gypsum etc.
- Lift floorboards and thoroughly examine timbers and subsite.
- Check for suitable floor ventilation.
- Look for any internal plumbing defects and water dripping from cold pipes as the result of condensation.
- Check (if possible) on history and use of the property.
- Evaluate ‘lifestyle’ e.g. use of central heating paraffin or flueless gas heaters, drying, washing and cooking, degree of ventilation etc.
Once any form of rising damp problem has been identified then it is essential that the risk of decay to any timbers is assessed and appropriate remedial measures undertaken.
REMEMBER: a combination of dampness and wood leads to potential rot
The primary task is to correctly identify the source of the rising damp problems. This is best achieved by the process of investigation and elimination. Extreme care must be taken, for example, in the winter months to eliminate condensation as one of the potential causes of dampness.
When there is more than one source of water ingress then it may be difficult to distinguish between their origins. Generally, the presence of active rising dampness is indicated by excessive moisture at the base of the wall which slowly declines on going up the wall. This moisture gradient is usually observed up to heights 1.5 meters but, depending on conditions and the structure of the masonry, it may rise to greater heights. Sometimes, a ‘tidemark’ can be observed running almost horizontally along the wall and the area below it being obviously damp. Dampness can rise to heights well in excess of 1 meter, a figure frequently quoted as the maximum height to which dampness can rise.
Find out more about Wamwalls damp proof treatment in Havant, Waterlooville, Emsworth, Gosport, Portsmouth, Hampshire, Chichester and Bognor Regis, Richmond, Twickenham, Isleworth, Ham, Kingston Upon Thames, Roehampton, Teddington, Kingston Vale, Brentford.