There are varying views on “how damp is damp”? They need to be related to appearance and perception issues, as well as purely structural considerations.
Dampness in buildings usually has one or more of four causes – Penetrating damp, rising damp, internal leaks or condensation. It is important to fully identify causes of dampness in order to ensure that they can all be rectified or controlled.
There are many external defects which will allow damp penetration, which should be at least inspected from ground level, with binoculars if high level inspection is not possible. An external inspection will identify areas to be inspected closely when inside, as a result of penetrating damp.
Rising damp is often diagnosed by patterns of moisture meter readings and plaster breakdown in walls, but can be brought about by bad building practices in construction, allowing dampness from the ground to bypass an existing damp proof course by “bridging”, which may be by plaster or floors internally, render or high ground levels externally.
Where Rising Damp has existed, it invariably leads to contamination of masonry which will persist even after the Rising Damp has been controlled by fitting of a damp proof course. Contamination also occurs due to other causes, such as chimney defects (which allow combustion products to leach into the masonry and cause internal staining), sea water spray in coastal areas, or contaminated building materials (such as unwashed beach sand). Control of contamination is the major reason for plaster replacement.
Condensation is an increasingly important problem, and is the most common form of dampness in UK buildings today. Concern for energy conservation, cutting of ever more expensive heating bills, and finite energy resources has resulted in more draughtproofing and better insulation. Unfortunately, this has often reduced air movement in buildings to the extent that condensation takes place and mould growth occurs, with possible damage to building contents, fabric, and health of occupiers. We can diagnose condensation problems and recommend appropriate solutions, not just “open the windows and turn the heating up” which is the stock response.