Damp (structural)

The unwanted moisture enables the growth of various fungi in wood, causing rot or mould health issues and may eventually lead to sick building syndrome.

Water removal and drying of wet building materials within 2 days will likely prevent mould and bacteria growth, therefore reducing occupants' vulnerability to disease.

The Homes (Fitness for Human Habitation) Act 2018[11] requires private landlords in England and Wales to ensure that houses that they rent are "free from damp.," A wide range of instruments and techniques can be used to investigate the presence of moisture in building materials.

In the UK, well built modern houses include damp proofing in the form of a synthetic damp-proof course (DPC), about 15 cm (6") above ground level, to act as a barrier through which water cannot pass.

[15] Wet materials, such as lumber stored unprotected outdoors before construction, can lead to increased humidity indoors for up to the second year of occupancy in the building.

If humidity levels do not agree with the time of the year and the temperature during seasons, mold infestation and deterioration of the building will occur due to moisture.

[19] If it is suspected that the problem is condensation, then a room should be sealed off with a dehumidifier left running for the recommended time and then further instrument tests made.

[20] Typical remedies for condensation include increasing background heat and ventilation,[21] improving the insulation of cold surfaces and reducing moisture generation (e.g. by avoiding the drying of clothes indoors).

In his 1954 book The Restoration of Old Houses, Hugh Braun highlighted problems inherent in certain types of render that were widely used in the late eighteenth century and throughout the Victorian era: "By the end of the eighteenth century a number of patent water-repellent cements were appearing on the market, the most popular of which, roman cement, continued in universal use throughout the Victorian era; many old buildings were rendered with this substance.

Rising damp is the common term for the transport of water in the lower sections of walls and other ground-supported structures by capillary action in porous materials.

[35]In July 1860 it was reported in The Engineer that At the Salford Hundred Quarter Sessions on Monday, it was officially stated by the Assize Courts Committee that the foundations which had been completed had been covered with asphalte by Messrs. Hayes and Co., of Liverpool, who guarantee that it shall withstand the rising damp.

This preventative may consist of a double layer of thick slates bedded in cement, or of patent perforated stone-ware blocks or of three-quarters of an inch of best asphalt.

[40]Rising damp is a phenomenon that is fully predicted by the laws of physics,[41] has been researched on a worldwide scale,[27] and has been documented since Roman times.

A former chairman of the construction arm of the Royal Institution of Chartered Surveyors (RICS), Stephen Boniface, has said that 'true rising damp' is a myth and chemically injected damp-proof courses (DPC) are 'a complete waste of money'.

[43]Konrad Fisher's article "The Fraud of Rising Damp" points out that the historic city hall in Bamberg stands in the river Regnitz and its bridge remains dry without any chemical, mechanical or electronic damp-proof course.

[45][46] In 1997 the housing disrepair team at Lewisham Council in south London were so convinced that rising damp was a myth that they offered a reward of £50 to anyone who could show them a genuine case of it.

Moisture penetration has been an ongoing problem for residences as evaporation occurs at the edge of the damp area, resulting in "tide marks" due to salt deposition.

[45] BRE Digest 245 lists several factors that can influence the height of the rise including rate of evaporation from the wall, pore sizes of the masonry, salt content of the materials and the soil, groundwater and degree of saturation, and use of heating within the property.

[50] A review of data and publications commissioned by the Property Care Association and carried out by the University of Portsmouth [27] concluded that "Rising damp is an age-old and ubiquitous problem."

The review looked at data and studies on rising damp from a number of countries including the United Kingdom, Portugal, Germany, Denmark, the Netherlands, Greece, Australia, and Malaysia.

These instruments are unable to accurately measure the moisture content of masonry, as they were developed for use on timber, but the reading patterns that are achieved can provide useful indicators of the source of dampness.

Adolf Wilhelm Keim describes the use of a hot bitumen remedial damp-proof course that is injected into holes drilled into a wall in his 1902 publication "The Prevention of Dampness in Buildings."

They are generally considered to be easier to use than other types of rising damp treatment as the method of installation is simply to insert them into the correct sized holes drilled into a mortar bed.

While there is evidence to suggest that these systems can be useful in moving salts in walls [54] there is little in the way of independent data to demonstrate effectiveness in treating rising damp.

"[14] The Royal Institute of Chartered Surveryors (RICS) publication "Remedying Damp" is more cautious about reliance on third party accreditation, casting doubt upon the validity of the test methods employed, arguing that trials are usually conducted using "specially built masonry panels – which do not match up in many respects to walls found in real properties," and that "if a DPC were proved to not work in a specially built masonry panel, this would be the more significant result.

[58] This replaces a draft BBA guidance note that said Damp-proofing creams differ from fluid-based damp-proofing treatments in a number of ways:[59] In his book, Dampness in Buildings, Alan Oliver refers to research carried out in Belgium regarding the effectiveness of different types of rising damp treatments: In Belgium, at the Centre Scientifique et Technique de la Construction (CTSC, 1985), research was carried out on the effectiveness of the main retrofit DPCs found in Europe.

He also suggests that damp-proofers have an incentive to carry out more replastering than is strictly necessary as it allows them to finish the job without having to wait for walls to dry out, resulting in faster payment.

These include an incompatibility with the soft bricks and mortars encountered in older buildings and a lack of insulation properties compared with more traditional plasters, resulting in an increased risk of condensation.

Such plasters offer a better solution than dense sand-cement renders when used on moderately salt-contaminated walls as their porous nature gives them insulation properties, resulting in a warmer surface temperature and making condensation problems less likely to occur.

It is best practice to delay replastering and redecoration for as long as possible following rising damp treatment, but this obviously creates inconvenience to the occupants of the affected building.