www.heritage-house.org

All about Damp in old houses... We've written another page to show you some of the things that are a result of condensation, and how to deal with it. The Rising Damp specialists just treat it as rising damp!!! Research what they say - then have a look at the Damp page of this site and see for yourself the fraud that is Rising Damp!

Managing Condensation in old houses and buildings

Condensation is a common problem in old houses, and to a lesser extent in new houses, which should comply with building regulations –these are meant to avoid problems such as condensation. Condensation in old houses causes the phenomenon most commonly called 'Rising Damp'

Temperature + Humidity = Condensation...

We have sophisticated, yet simple measuring equipment which allows us to precisely monitor the levels of humidity and the temperature in your house. From these, we calculate the 'Dew Point' - the temperature at which condensation will form. It is then a simple process to check the temperature of walls and pinpoint those which are at risk, and those which actually have condensation forming on them.

A recent survey provided the best example we could ever quote. Our client asked us to survey his house and try to ascertain why mould was suddenly appearing on the walls around the house. He complained that there were damp patches all over the house, and mould growing on clothes and belongings in cupboards. Plaster was peeling in some areas, together with paint finishes. As soon as we entered the house, we took ambient humidity and temperature readings - these showed humidity of over 70% and a room temperature of 22 degrees C. The dew point, at which temperature condensation will start to form, was in this case calculated at 13.5 degrees. A spot check of the walls in the worst affected areas (using a very sensitive thermocouple) showed that they were all at or below dew point, and thus condensation was actively forming - which is why the walls were wet.. We opened a window at the front of the house by an inch, and the back door by a similar amount, which was just enough to allow a flow of air into the house. Within two hours, condensation on the walls had disappeared. Checks of the humidity and temp levels showed that the humidity had dropped to below 60%, and the temperature only by 3 degrees - the house felt warmer, and there was now a big gap between the temperature of the walls, and the dew point, which had dropped considerably. Our client was delighted, his problems were essentially solved - we recommended a series of small changes in his lifestyle, some ventilation fans, and air vents - all at minimal cost, and the house is now starting to become dry and mould free. Luckily, we got to this one before the plaster dropped off and damage occurred to finishes.

These two photos below are probably the most significant examples of what can happen to a wall that I've ever seen. Look carefully at them, and the pattern of 'damp' that is repeating in the first picture - then have a look at the detailed explanation below the photos...

This is a wall between two rooms in an old farmhouse. The wall is papered with an impervious paper which has trapped condensation at the base of the wall. The paper has gone mouldy - the glue has rotted, and the whole thing is horrible. the glue is easily removed by peeling it back - revealing a bone-dry lime plaster underneath, and no evidence of so called 'rising damp'

However... Look more closely. At the top of the photo, where the wallpaper starts again, you can see that the plaster itself is bubbling and soft - it's actually damaged. What has caused this damage I wonder...? For the answer, we have to look at the other side of the wall - in the photo to the right...

In this photo we can clearly see that wallpaper has been applied over a dark grey water inhibiting plaster which had trapped all kinds of problems. This was chipped off to reveal lovely dry lime plaster. But..... above it you can just see a dark reddish patch - and a semi circular break line between lime plaster and newer cement render above it. Look at the shape of the damaged plaster in the previous photo at the same level. Now you can see that the cement render on this side is causing that crumbling lime plaster in the first photo.

Every action with an old house involving anything impervious, anything that traps water and stops the building breathing, will result in an unpleasant reaction somewhere else!

This is a fantastic example of condensation in a corner of a bedroom. It had formed on one wall, causing damp, mould, fungus - you name it. We scraped the paint and fungus off, to expose cement render on brickwork. It doesnt go round the corner to the wall on the right.

I wonder why?

We tested the temperature and humidity of the walls. The wall on the right is covered with original lime plaster. The temperature probe showed a temperature of almost 2 degrees higher for the lime plaster than the wall with the mould on it - which was cement rendered and nearly 2 degrees colder.

Another example of how modern materials dont work, and traditional materials are warmer and drier.!