Dampness can cover a whole magnitude of different things ranging from rising damp to leaking from plumbing installations and even condensation from cooking. The main causes of dampness in a property are:
Those of us who did sciences at school will have been involved in placing ink on blotting paper then standing it in water and watching the staining rise up through the blotting paper. That exact same effect occurs in building materials, to a lesser or greater extent, depending on the materials used. This can occur quite commonly where there is inadequate damp proofing (a barrier put into the structure to prevent water leaking up through the materials) or where the damp proof course has broken down and failed.
The effects of rising damp can be quite visible with an obvious tidemark to decorative finishes. In general, rising damp can rise to a level of approximately one metre above ground level.
It is not uncommon for there to be a perfectly functional damp proof course in place. However, if the external ground has been built up to a level above the damp proof course, or where another structure abuts the building, what is known as 'bridging' can occur. This means that the water travels around the damp-proof course and on up the wall.
Leakage from the external building fabric
This can be described in various ways by the surveyor but commonly it will be one of the following:
Penetrating damp normally relates to water and moisture which has been allowed to travel horizontally through the building fabric from the outside into the internal portions of the building fabric. This would normally be through porous stone or cracks in the external rendering.
Leakages are fairly easy to understand and normally relates to water coming in and traveling vertically down through the building from defects in the external details. This would include water from roof leaks but can include other items that have been allowed to deteriorate i.e. windows.
This type of leakage can often be a result of poor design, poor materials, poor workmanship, storm damage, and/or poor maintenance.
Leakage also covers all the water carrying systems in the property, so hot and cold water, the heating systems (these would also involve tanks and general pipework), kitchen appliances, sanitary fittings and, more commonly in today's world, shower and bath leaks.
This again can be as a result of poor design, poor materials, poor workmanship, poor maintenance, but also corrosion, puncturing etc.
Condensation relates to high levels of airborne moisture that then condenses on cold surfaces. It is most commonly noticed at windows on cold mornings with water running down the glass. It can however be a substantially more significant problem affecting decorative finishes and in its most extreme can affect concelled structural parts of the building as well as posing a health threat.
It normally appears by way of moisture staining and black mould in a triangular form in cold, dark corners of a room or behind furniture hard against the wall where there is a lack of ventilation in cold spots.
Condensation itself is caused by a combination of all the previous factors allowing moisture to build up within the building in conjunction with a lack of ventilation and changes in our life styles.
Condensation is modern day problem, whereas traditionally forms of construction allowed high levels of ventilation (draughts) through the building. Doors and windows etc were not fully sealed, open fireplaces and basic timber flooring all allowed for ventilation through their numerous gaps. The traditional roof structure in Scotland also allowed a high degree of ventilation through the roof structure. Modern construction with sealed double glazed units, draught-excluded doors, blocked fireplaces and fitted carpets etc have all prevented an appropriate flow of air through the building, allowing moisture to increase.
Traditionally clothes washing was carried out in the wash house and bathing was limited and was carried out in a well ventilated specific area. Clothes were dried by hanging them outside. A modern home goes against all these principles and results in condensation.
It should also be noted that the three biggest areas for condensation are the bathroom, kitchen and the bedroom, where, for example, two sleeping adults can create a significant level of moisture in an unventilated room, creating a considerable condensation risk.
What effects do all these forms of damp have?
Water in a building can be seen in the following three categories:
1. The moisture held in the exterior fabric can often be seen by obvious defects such as decay to external timbers, staining and erosion of stonework, and corrosion of rainwater installations. Longer term this can result in accelerated deterioration due to frost damage pushing render off and spalling or splitting stone work .
2. The next is moisture that is held within the body of the building and has been trapped within the materials and can cause problems to the materials ultimately resulting in deterioration of the structural stability of the building. Deterioration to timber and metal structures is common as they are susceptible to rot and corrosion issues in particular.
3. Finally, the internal impact of dampness, which cannot be understated. This is often the main concern for most individuals as it effects the aesthetical appearance of a dwelling. The impact of internal dampness can result in collapsed ceilings, staining, salts on finishes, softening and deterioration of various materials and even odours!
It is important to note that all of these factors which stem from dampness can often have further impact on:
- the building itself
- to the health of the occupant
- your bank balance in the cost of repairs
- your insurance policy /premiums /excess
- the value of your property
The Home Report, or independent surveyor's report, may recommend that a specialist report be prepared. It is important, if there is a damp issue, to get advice. Any specialist report should ideally be passed to either the surveyor who carried out the Home Report or your own independent surveyor to ensure that the specialist report truly covers the issues and is an appropriate solution to the problem.
In most cases a balanced approach is required and the surveyor should be able to give some indications as to the combined approach that will be required and whilst a fee may be charged, in the long term this will be worth the expenditure.