Statistically, building defects account for the majority of damp, water ingress and condensation issues in property.
Rising damp, that is to say dampness brought up from the ground via capillary forces within building materials such as brickwork actually account for around 30% of complaints of dampness.
The initial diagnostic survey is therefore of utmost importance in identifying ALL of the issues which may have a bearing on a particular dampness problem. Dampness on a wall at low level is not necessarily due to rising dampness only. There may be other factors to consider and all need to be identified to produce a schedule of remedial works which will provide a long term professional solution.
It is not sufficient having identified damp at low level on a ground floor wall to attribute this to rising damp. It is more common than not that there will be factors to consider other than dampness rising upwards through the brickwork.
It is important that not only the effects of dampness are repaired but the ROOT CAUSE is also diagnosed and correctly solved. If it is not, superficial repairs and remediation may soon fall again into disrepair with the consequential additional expenditure, inconvenience, disruption and wastage of time and effort.
Some examples are as follows:
- Bridging of existing damp proof course
- Bridging is a common problem and can occur where dampness travels around horizontal or vertical damp proof courses. Causes of bridging include:
- Debris in the wall cavity which can often reach 30-60cm above ground level.
- Cavity wall insulation can act as a wick, transferring dampness upwards when in contact with the ground or across the cavity where water / dampness penetrates the external side.
- Internally plaster applied too low to the floor bypassing the damp proof course.
Defects in the external building fabric
Defects higher up in the external building fabric allow water to ingress which works its way through the wall structure in both cavity and solid walls to eventually appear at lower level. A competent and experienced specialist surveyor will identify the risks and likelihood of this occurrence.
Dilapidated and eroded pointing. Rainwater, frost action and gaps caused by structural movement can allow water to ingress into the cavity. Cavity wall construction should allow water to run down the inside face of the external skin but cavity wall insulation, incorrectly installed wall ties and mortar droppings act as a damp bridge causing dampness to internal walls.
Defective mastic seals around windows due to deterioration of the mastic or the incorrect type of mastic has been used. Mastic must be specified correctly to the particular circumstances.
Roof defects, particularly around the eaves level and verges are a common cause of water ingress down the cavity. Roof coverings such as slates and pre-cast concrete tiles along with fixings around eaves level and verges are prone to weathering and deterioration as is the roofing membrane underneath. Many older buildings still retain their original roof covering and therefore do not have the secondary defence of roofing felt underneath. As such when a defect in the roof covering develops, rain water immediately enters through. Where the roofing felt deteriorates at eaves level and verges, defects in the roof covering higher up will allow water to ingress and run down the roofing felt to enter where the roofing felt has deteriorated. Therefore dampness to a wall could in fact have its source higher up the roof structure.
Lead lined stone gutters are also a common problem relating to water ingress down cavities. The lead linings expand and contract greatly due to temperature changes which results in splits developing particularly at the junction with neighbouring properties and where a drain outlet penetrates the lead lining. Where the water runs through, it will find a course into the wall structure usually in the gap between the gutter stones.
Summary
At Dryabode Property Care, we believe in solving the root cause of all building defects having a bearing on a particular damp issue and getting it right first time which in our opinion is far less expensive in the long run.
It is imperative that the initial diagnosis is carried out by a properly qualified, accredited, experienced, professional surveyor who specialises in this field. This will ensure that any damp issue is properly diagnosed and ALL defects which have a bearing on the problem are identified. A comprehensive schedule of remedial works can then be tailor made to the particular problem to provide a long term solution which works first time and provides peace of mind.