Every so often, there is talk about rising damp being a myth, and that it does not exist. Well, any property owner who has seen the tell-tale signs of dampness in their walls, as a result of dampness from the ground, will know that it certainly does exist. In 2020, rising damp certainly does exist and its existence is due to a number of reasons, which include, but are not limited to:
- Failure of an existing damp proof course (DPC)
- Bridging caused by raising of external ground (flower beds) or internal floors. This often happens over the years where suspended timber floors have been replaced with solid floors.
- The absence of a DPC which is usually in older buildings i.e. pre-Victorian.
Permeable building materials such as brick, stone and mortar allow damp from the ground to rise by capillary action. One of the biggest problems with damp rising from the ground is that it will result in the movement of ground salts, which include chlorides and nitrates. These salts are hygroscopic and are moisture absorbent. They tend to migrate into the internal plaster and due to their presence, when the humidity in the building is high, dampness will become more apparent. Tell-tale signs of dampness may appear in patches on the wall surfaces.
Rising dampness within a wall rarely goes higher than around 600mm up from floor level. The visual evidence can extend higher and this is usually due to high levels of hygroscopic salts or, could be due to another factor, such as water ingress from external building defects. An experienced Surveyor will be able to identify this.
It is important to mention that the amount of water which is absorbed by salt contamination will vary as a result of the relative humidity of the atmosphere within the room/property.
Salts which appear as white flour like dusting or crystallisation deposits on the wall surface are known as ‘efflorescence’. This can ruin decorations and can cause a break-down and spalling of the existing plaster/decorative finishes. The presence of salt efflorescence indicates that water has been on the surface but has evaporated. This is where salt efflorescence differs from hygroscopic salts, which continue to absorb moisture into the plaster, until they are removed.
Salts which appear as white flour like dusting or crystallisation deposits on the wall surface are known as ‘efflorescence’. This can ruin decorations and can cause a break-down and spalling of the existing plaster/decorative finishes.
Rising damp increases the moisture content within the home and reduces the surface temperature of walls, which can lead to additional problems such as:
- Decay, caused by both wet rot and dry rot to the floor timbers in contact with damp masonry as well as to joinery timbers such as skirting boards and the bottom of door frames
- Infestations by woodboring insects particularly if the ground floor is of a suspended timber construction.
- Condensation forming where the surface temperature of walls is colder.
Methods to determine moisture
There are three different ways to determine and/or measure moisture in brickwork and other masonry.
- Electrical – Conductivity. Radio Frequency and Capacitance
- Chemical – by use a Carbide method
- Gravimetric – oven drying method
The most common less destructive approach is an Electrical method, using meters such as a Protimeter MMS2, which can be taken quickly and easily.
Conductivity Meters is completed by placing two probes on the surface, or by embedding them in the depth of the wall. The resistance of the wall and the meter’s reading are influenced by the moisture content in the wall. Radio frequency search mode (on the Protimeter MMS2) is where the machine is placed on the surface of the wall and a reading is taken beneath the plaster.
This is useful in experienced hands to interpret the results given, which are normally taken from the base of the wall rising upwards to provide a moisture profile.
Chemical Methods together with Gravimetric Methods require destructive drilled samples to be taken which is a far less practical option.
Remedial action – what to do
The most important thing to do is to arrange to have an inspection from an established company with years of experience carrying out damp proofing, who are members of the Property Care Association (PCA). They will arrange for one of their CSRT (Certified Surveyor Remedial Treatment) Surveyors to carry out an inspection of the specified area and provide a detailed Report/Quotation.
This report should list the type, age and construction of the property, together with their observations both internally and externally. Where applicable, recommendations will be made for works required i.e. installation of a Chemical Damp Proof Course, together with associated works, such as specialist replastering using a salt resistant specification/plaster mix.
Why come to Preservation Treatments?
We have been established since 1972 and we are very proud to say that a significant amount of the work which we carry out comes through existing clients and recommendations.
We are also proud to confirm that:
- We are members of the PCA (Property Care Association)
- Some of our Surveyors are also PCA WDS (Waterproofing Design Specialists)
- All our Surveyors are CSRT qualified with continued CPD training throughout their year
- We are able to offer GPI back-up insurance (Guarantee Protection Insurance) on most aspects of our work
- All staff are trained in Health and Safety aspect of work
- We have numerous trade affiliations including:
- CHAS (Construction Health and Safety
- SAFE CONTRACTOR
- BS ISO 9001:2015 Quality Management
- BS ISO 14001:2015 Environment Management system
If you require some remedial damp proofing why not call a specialist so they can give you their expert opinion.