Property: Tubes that suck up your money, but not the damp

DOCTOR ON THE HOUSE; A discredited technique for keeping walls dry is still being flogged by the building trade

IN 1919, during the Great War peace conference, a member of the British military delegation noticed something interesting in the Palace of Versailles: a row of small circular vents along the bottom of a wall. After some inquiries the delegate - one General Brown - found that the vents concealed ceramic tubes set into the wall for damp proofing, a process that had been patented in 1908 by a Belgian, Monsieur Knapen.

General Brown introduced the Knapen tubes into Britain under licence, and apparently enjoyed some commercial success with British Knapen Ltd before selling up. Ceramic tubes continue to be made, marketed and installed in British homes.

The only trouble with a damp-proofing system which uses ceramic tubes is that it doesn't work.

At first sight, the idea of drilling holes in a wall to remove moisture might seem logical. After all, increasing the exposed surface area should assist evaporation, shouldn't it? But there was always supposed to be more to the tubes than that. The fine pores of the ceramic clay would actually draw dampness out of brick and stone. The angle at which the tubes were stuck in the wall would cause the moist air to flow away by gravity. It was even thought that the Dutch clay from which the tubes were made had special properties.

But any physicist will tell you that the system cannot work because the finer the pores, the greater the capillary action, or suction - and this makes a material hold on to its moisture, not dry out by evaporation. Any evaporation at the surface of the tubes would cause a build-up of dissolved salts, which would attract moisture from the air and actually make the wall damper. These suspicions were verified by experimental work published in Germany in the 1960s. Ceramic tubes do not make walls dryer, and in some cases they can make them wetter.

Even the damp-proofing industry trade body, the British Wood Preserving and Damp Proofing Association (BWPDA) has a code of good practice which advises against using ceramic tubes.

But nobody in the building game ever let a few facts fog the issue. The contents of foreign-language science journals do not find their way easily into the British press. So 30 years after they were shown to be worthless, ceramic tubes are still being marketed, and even described in construction textbooks as a proven way of keeping walls dry.

Watch out for anyone who tells you your home needs damp-proofing after using electrical moisture meters to diagnose rising damp. These give high readings on walls even when the actual moisture content is low, so that whatever the "damp-proofing" employed, it was probably unnecessary in the first place. Second, any damp-proofing contractor challenged over the efficacy of his installation will take a drilled sample from the wall and pronounce it dry - "proving" his damp proofing has worked.

Two lessons from this: anyone wishing to avoid unnecessary damp-proofing work should ask for the drilled sample test to be done first; and anyone thinking of having the ceramic tube system installed should think twice, or they could watch their money go straight down the tubes.

q You can contact Jeff Howell at the 'Independent on Sunday' or e-mail: Jeff@doctoronthehouse.demon.co.uk

Suggested Topics
Start your day with The Independent, sign up for daily news emails
Sport
England's women celebrate after their 3rd place play-off win against Germany
Women's World CupFara Williams converts penalty to secure victory and bronze medals
Arts and Entertainment
Ricardo by Edward Sutcliffe, 2014
artPortraits of LA cricketers from notorious suburb go on display
News
newsHillary Clinton comments on viral Humans of New York photo of gay teenager
Arts and Entertainment
The gang rape scene in the Royal Opera’s production of Gioachino Rossini’s Guillaume Tell has caused huge controversy
music
ebooks
ebooksAn introduction to the ground rules of British democracy
Latest stories from i100
Have you tried new the Independent Digital Edition apps?
Independent Dating
and  

By clicking 'Search' you
are agreeing to our
Terms of Use.

iJobs Job Widget
iJobs Money & Business

Recruitment Genius: Sales Assistant / Buyer

£15000 - £17000 per annum: Recruitment Genius: This company offers a range of ...

Recruitment Genius: Customer Service Advisor

£15000 - £16000 per annum: Recruitment Genius: Customer Service Advisors are r...

SThree: Trainee Recruitment Consultant

£20000 - £25000 per annum + OTE £45K: SThree: SThree were established in 1986....

Recruitment Genius: Compliance Manager

£40000 - £60000 per annum: Recruitment Genius: A Compliance Manager is require...

Day In a Page

The Greek referendum exposes a gaping hole at the heart of the European Union – its distinct lack of any genuine popular legitimacy

Gaping hole at the heart of the European Union

Treatment of Greece has shown up a lack of genuine legitimacy
Number of young homeless in Britain 'more than three times the official figures'

'Everything changed when I went to the hostel'

Number of young homeless people in Britain is 'more than three times the official figures'
Compton Cricket Club

Compton Cricket Club

Portraits of LA cricketers from notorious suburb to be displayed in London
London now the global money-laundering centre for the drug trade, says crime expert

Wlecome to London, drug money-laundering centre for the world

'Mexico is its heart and London is its head'
The Buddhist temple minutes from Centre Court that helps a winner keep on winning

The Buddhist temple minutes from Centre Court

It helps a winner keep on winning
Is this the future of flying: battery-powered planes made of plastic, and without flight decks?

Is this the future of flying?

Battery-powered planes made of plastic, and without flight decks
Isis are barbarians – but the Caliphate is a dream at the heart of all Muslim traditions

Isis are barbarians

but the Caliphate is an ancient Muslim ideal
The Brink's-Mat curse strikes again: three tons of stolen gold that brought only grief

Curse of Brink's Mat strikes again

Death of John 'Goldfinger' Palmer the latest killing related to 1983 heist
Greece debt crisis: 'The ministers talk to us about miracles' – why Greeks are cynical ahead of the bailout referendum

'The ministers talk to us about miracles'

Why Greeks are cynical ahead of the bailout referendum
Call of the wild: How science is learning to decode the way animals communicate

Call of the wild

How science is learning to decode the way animals communicate
Greece debt crisis: What happened to democracy when it’s a case of 'Vote Yes or else'?

'The economic collapse has happened. What is at risk now is democracy...'

If it doesn’t work in Europe, how is it supposed to work in India or the Middle East, asks Robert Fisk
The science of swearing: What lies behind the use of four-letter words?

The science of swearing

What lies behind the use of four-letter words?
The Real Stories of Migrant Britain: Clive fled from Zimbabwe - now it won't have him back

The Real Stories of Migrant Britain

Clive fled from Zimbabwe - now it won’t have him back
Africa on the menu: Three foodie friends want to popularise dishes from the continent

Africa on the menu

Three foodie friends want to popularise dishes from the hot new continent
Donna Karan is stepping down after 30 years - so who will fill the DKNY creator's boots?

Who will fill Donna Karan's boots?

The designer is stepping down as Chief Designer of DKNY after 30 years. Alexander Fury looks back at the career of 'America's Chanel'