The Global View on Rising Damp – Present and Past

The first known written historical reference about rising damp goes back to ancient Rome. The Romans, being excellent engineers, that have built some masterpieces that lasted over 2000 years. Historic records show that they not only were aware of rising damp, but they have also devised efficient solutions to combat it.

Roman architect and engineer Vitruvius in his famous Ten Books on Architecture has described the type of plaster mix that should be applied on walls near ground level subject to ground moisture:

"I shall next explain how the polished finish is to be accomplished in places that are damp, in such a way that it can last without defects. First, in apartments which are level with the ground, apply a rendering coat of mortar, mixed with burnt brick instead of sand, to a height of about three feet above the floor, and then lay on the stucco so that those portions of it may not be injured by the dampness."

The Builder was a journal of architecture published between 1843 and 1966. Issues from year 2 (1844) mention dampness rising from the ground due to capillary attraction. As a solution, to prevent the ascent of moisture up the walls, it recommends the use of slate inside the walls.

This professional textbook from 1851 is a practical manual written for architectural students, engineers, contractors and builders.

Dedicating a whole chapter to dampness, including to the prevention of rising damp, stressing the importance of separating the foundations from the rest of the wall with a damp proof course, to stop the upward migration of dampness.

"... to intercept entirely all communication between the foundation below and the walls above, no damp, as far as we have observed, can possibly find its way upward; and however damp the work below the asphalte (DPC) may become, that above will remain perfectly dry and unaffected."

French architects, independently, came to the same conclusion. Even if the footing of a building is always underwater (e.g. in a lake), using less than half an inch thick asphalt DPC keeps the walls completely dry.

This paper read on 12 Jan 1863 at the General Meeting of the RIBA, discusses the sanitary aspects of rising damp in old buildings, and various damp proof course options as a natural remedy to the problem - about 20 years ahead of global UK sanitary reforms.

"The great evils, in a sanitary point of view, are doubtless caused by damp rising up the walls by capillary attraction. (...) Our remedies for this have generally been a layer of asphalte throughout the thickness of the walls, "sheets of lead", a course of slates bedded in cement, and sometimes compounds of gas-tar, pitch, sand etc."

A new damp proof course is also presented to the attending architects - a layer of perforated bricks, laid as a row of ordinary bricks, to prevent the rise of moisture, while also improving underfloor ventilation.

Some of the architects' comments on this damp proof course technology included:

• Many new inventions are adopted with difficulty, including the idea of damp proof courses.
• Some concerns about their additional cost. Damp proof courses have often been skipped to save on material and labour costs.
• They should be better tested, although in buildings used (e.g. the great Artillery barracks at Colchester) they were very efficient.
• Their aesthetic look is a positive.
• Architects were in agreement that damp proof courses were the best method of keeping damp down.

A report of the British Medical Journal dating 20 Dec 1873 discusses various sanitary aspects of rising dampness in houses, hospitals and public institutions.

Various damp proof course technologies used by architects are mentioned in the paper, including double course slates, Welsh slate bedded in cement, sheets of lead, hot asphalt DPCs, glazed bricks and vitrified stone-ware tiles.

The paper also advises the retrofitting of a damp proof course into old buildings, which turned uninhabitable buildings into perfectly healthy ones.

This 3-volume publication from 1876 was the official syllabus of a three-part advanced building construction course. A whole chapter is dedicated to the problem of dampness and how to efficiently overcome it, including rising damp, penetrating damp and falling damp from the roof or gutters.

Various damp proof course technologies are also discussed, making reference to the fact that slate DPCs embedded in cement are liable to crack and thus fail.

Glazed pottery slab damp proof course built into the wall:

Lastly, according to an official report from the 1867 Paris Exhibition, some interesting technical facts from the book on how much water saturated brickwork can hold:

• In England, common bricks can absorb as much as a pint or pound of water
• An ordinary cottage consisting of 12,000 bricks, can hold about 6.5 tons of water when saturated 
• Porous sandstone fit for building purposes may contain about half a gallon of water per cubic foot. (about 80 liters / m³)

Realizing the effect of damp walls onto the health and well-being of inhabitants, between the 1870s - 1890s a number of health bills have been passed throughout UK, all of them recommending damp proof courses as a means to combat capillary rising damp.

"We must now turn our attention to the walls, which is equally necessary to protect from rising damp. If you plant a brick or stone wall o ground which is capable of retaining moisture, it will inevitably happen that unless you take means to stop its progress, the moisture will climb up the walls in obedience to the law of capillary attraction."

Solution to the problem is a vitrified (glass-like) layer of bricks or two layers of slate.

The book also provides technical advice with drawings, presenting the wrong way of laying a slate damp proof course, if gaps are left between them.

Clause 96 of the The London Public Health Act from 1891 stipulates the use of damp proof courses for underground rooms: "Any underground room (...) shall not be let or occupied unless (...) every wall of the room is constructed with  a proper damp proof course."

The book also discusses in details most building materials used in the 19^th century, highlighting that stone houses built without a damp proof course are more or less damp... 

... and common lime mortar will not stop rising damp from the ground.

"The foundation of walls built of common lime mortar, will always be damp, from capillary attraction - common lime mortar offering no impediment to the absorption of the moisture from the soil, or to its gradual passage upwards into the main wall of the house."

This book published in 1870 presents 45 private residences of its time, focusing on practical aspects of house building, including: how to properly build walls, construct floors, roofing, ventilation, drainage, what materials to use etc.

The problem of dampness is also discussed in detail, with practical advice on how to prevent it, overcome it and build a dry, comfortable home. Rising damp must always be addressed by laying a damp course under every wall, whether internal or external.

"Damp course: a provision should always be made to prevent any damp rising up the walls from the foundations."

This book published in 1905, presents examples of typical domestic buildings, including some of the most noteworthy houses from Victorian England. The book highlights damages caused by rising damp in many old 17^th century cottages - making some rooms almost unusable for living.

"... When the houses were built in sloping sites... by means of terraces and steps... these lower rooms, owing to wet and damp, are now almost unusable except at store places."

The reason why the ground floor rooms of many old cottages were wet and unhealthy, especially during winter time, was lack of damp proof courses, an unknown technology at the time when these cottages were built.

"The ground floor... laid directly on earth, with the result that the moisture readily soaked through, doubtless causing the rooms to be wet and unhealthy, and as damp proof courses were unknown when these houses were built, the lower part of the walls in winter time was moist and damp."

This book published in 1914, dealing with the restoration of old houses - weather cottage, farm house or small manor house - presents is detail the history, problems and restoration challenges of 40 old buildings stretching back 5 centuries.

Problems caused by rising damp are repeatedly highlighted, linking the problem and associated damages to lack of damp proof courses, unknown when these buildings were originally built. Several such examples are presented, and poor workmanship is also mentioned.

"Some people are apt to suppose that the buildings of historical periods were constructed on particularly sound lines. That, however is hardly the case. It is to the nineteenth century that we owe the use of such devices as damp-courses, and the lack of them in early buildings has not only shortened their lives, but many many of them uninhabitable, sometimes beyond redemption."

"...the principles laid down by the Society for the Protection of Ancient Buildings. It is not only conservative in the preservation of every scrap of old work, but eminentlv satisfactory in appearance. For the needful repairs to the walls bricks were made locally of the same size as the old ones. The attitude of the S.P.A.B., familiarly known as the Anti-Scrape, is sometimes more rigorous in respect of the alteration of old buildings than some antiquaries can endorse. Its work has been of immense value, however, in forming public taste and in checking the vandalism which raged unhindered before the Society was formed."

This book published in 1915, written by the Medical Officer of Somerset County, discusses important aspects of rural housing, including: the housing shortage, housing conditions, health and sanitary problems etc. The effect of various types of dampness are discussed in detail, based on the findings of professional surveyors.

"A very considerable proportion of country cottages are damp... due to a combination causes. One prevalent cause is the absence of proper foundations and damp-proof courses. There is nothing to prevent the wet from the earth rising up the walls, and it does so rise."   

Rising Damp is listed as a major problem that can be remedied with difficulty. The solution is fitting a solid DPC while other works are being undertaken. Failing to do so, the lack of a damp proof course, often makes old buildings uninhabitable, also resulting in their long-term decay.

"The provision of a damp course... is an expensive and troublesome matter. It has to be inserted... to prevent houses from being condemned." (Def: condemned: officially classed unfit for living)