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Damp Proofing

Will the holland damp proofing air vent system work?

4 Answers from MyBuilder Damp Proofing Specialists

Best Answer

Holland damp proofing can not work on a 9 inch wall all you are doing is fitting air bricks there is nothing stoping rising damp from rising
The so called Holland damp proofing system (sometimes referred to as the Schrijver system ) is yet another snake oil system that is pushed by very slick sales presentation in the UK as being the cure-all for damp. Both these companies have been investigated several times by the Advertising Standards Authority, and asked to remove or amend their advertising claims. The ASA stated in 2002 that 'the advertisers had proved neither that the Schrijver System stopped rising damp, nor that it reduced the moisture content caused by penetrating damp, condensation and mould'

There seem to be various versions of it - each as bad as the other. Professional videos are shown of chocolate box cottages with wallpaper peeling off the walls (in classic condensation patterns that could be cured by opening windows!). They claim to have won prizes for their system.. One was from a Dutch 'infotainment' tv show called National Suggestion Box where according to Jef Howell, the winning 'invention' was voted for by a studio jury!!

It is based on a system of 'Knapen Tubes' developed as early as 1908, and never shown scientifically to work.There are a few variations on it - all of them involving putting bricks or porous pots of some sort into the wall.

The system uses horrible, unsightly bricks or porous tubes which are drilled into the walls all around the house which supposedly allow moisture to escape from the walls. Unsurprisingly, most, if not all of the photos and films they'll show you are of houses which are covered in thick coats of cement render. Of course the wall is sopping wet - and anything that breaks the render will release water - far simpler just to take the render off!!

I have been in the building for over 44 years a lot of rising damp is mostley because the damp course as been bridged either from the out side or the inside or the inside walls have been plastered and not used the right stuff to carry the job out in most cases builders have used the cheap option ,and if the damp is more then one meter high it is not rising damp open a window

Oh... and did I say that cement is not porous? That it traps water? So whenever I do a survey and find these stupid blocks drilled into a sopping wet wall - they are fixed in place with... you guessed it... cement - so the wall could never breathe into them anyway cos the damn things are surrounded by cement.

report them to Trading Standards. Their system is NOT approved for use in the UK - The BRE has not tested and approved it, and there is a much easier and cheaper way to sort the problems out that they show on the various websites that use this ridiculous system - open a window, and follow the instructions on the site for reducing condensation and cement trapped moisture.


Answered 17th Apr 2015

I have had the pleasure in researching this subject in the past in great detail and in particular building envelope materials, moisture effects, dampness, condensation etc.
In short, if you have a modern cavity wall building, then I fail to see how this could offer a cost effective solution to penetrative or rising dampness. I would be looking closely at a problem relating to a building envelope failure first and solving the root cause, more often than not something fairly straight forward like a shrinkage crack, poor external drainage or a leakey gutter. If on the other hand you have solid masonry or stone walls, then the theory appears to be sound. I can not say I have used this system or indeed seen it been used, but I would certainly look closely at the cost effectiveness, the manufacturers claims and product warranty with great interest.
Kind regards,

Kieran Gannon MCIOB
Chartered Builder.


Answered 4th Apr 2011

The Holland system will work within certain criteria however damp comes in many disguises , It is always worth asking a local well established damp firm or builder to take a look, dont be put off if the damp company asks for a survey Fee , you get what you pay for.


Answered 17th Apr 2015

Yes the Holland Damp Proof system works and has been successfully used to treat damp in thousands of UK properties since 1999. The system uses special damp regulating bricks which are installed from the outside, so the customer doesn’t have the mess and expense of replastering afterwards. We also now offer other products for a variety of damp problems. Our damp experts cover mainland UK from local offices, and give honest advice, unlike some other companies highlighted in the Which? report January 2012.

Holland Damp Proofing


Answered 22nd Jul 2014

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