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
PROMOTED VIDEO
News
ebooksAn evocation of the conflict through the eyes of those who lived through it
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

Client Services Executive / Account Executive - SW London

£23000 - £26000 per annum: Ashdown Group: Account Executive / Client Services ...

PA to CEO / Executive Secretary

£36000 - £38000 per annum: Ashdown Group: Executive PA to CEO & Executive Dire...

Generalist HR Administrator, Tunbridge Wells, Kent - £28,000.

£25000 - £28000 per annum: Ashdown Group: Generalist HR Administrator - Tunbri...

Management Accountant

£30-35k + Excellent Benefits: Guru Careers: We are seeking a Management Accoun...

Day In a Page

Kate Bush, Hammersmith Apollo music review: A preamble, then a coup de théâtre - and suddenly the long wait felt worth it

Kate Bush shows a voice untroubled by time

A preamble, then a coup de théâtre - and suddenly the long wait felt worth it
Robot sheepdog technology could be used to save people from burning buildings

The science of herding is cracked

Mathematical model would allow robots to be programmed to control crowds and save people from burning buildings
Tyrant: Is the world ready for a Middle Eastern 'Dallas'?

This tyrant doesn’t rule

It’s billed as a Middle Eastern ‘Dallas’, so why does Fox’s new drama have a white British star?
Rachael Lander interview: From strung out to playing strings

From strung out to playing strings

Award-winning cellist Rachael Lander’s career was almost destroyed by the alcohol she drank to fight stage fright. Now she’s playing with Elbow and Ellie Goulding
The science of saturated fat: A big fat surprise about nutrition?

A big fat surprise about nutrition?

The science linking saturated fats to heart disease and other health issues has never been sound. Nina Teicholz looks at how governments started advising incorrectly on diets
Emmys 2014 review: Can they genuinely compete with the Oscars

Can they genuinely compete with the Oscars?

The recent Emmy Awards are certainly glamorous, but they can't beat their movie cousins
On the road to nowhere: A Routemaster trip to remember

On the road to nowhere

A Routemaster trip to remember
Hotel India: Mumbai's Taj Mahal Palace leaves its darker days behind

Hotel India

Mumbai's Taj Mahal Palace leaves its darker days behind
10 best pencil cases

Back to school: 10 best pencil cases

Whether it’s their first day at school, uni or a new project, treat the student in your life to some smart stationery
Arsenal vs Besiktas Champions League qualifier: Gunners know battle with Turks is a season-defining fixture

Arsenal know battle with Besiktas is a season-defining fixture

Arsene Wenger admits his below-strength side will have to improve on last week’s show to pass tough test
Pete Jenson: Athletic Bilbao’s locals-only transfer policy shows success does not need to be bought

Pete Jenson: A Different League

Athletic Bilbao’s locals-only transfer policy shows success does not need to be bought
This guitar riff has been voted greatest of all time

The Greatest Guitar Riff of all time

Whole Lotta Votes from Radio 2 listeners
Britain’s superstar ballerina

Britain’s superstar ballerina

Alicia Markova danced... every night of the week and twice on Saturdays
Berlin's Furrie invasion

Berlin's Furrie invasion

2000 fans attended Eurofeurence
‘It was a tidal wave of terror’

‘It was a tidal wave of terror’

Driven to the edge by postpartum psychosis