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We are often asked to carry out defect reports on houses built from the 1930's to the 1950's. These problems relate to damp and condensation and thermal efficiency. We are particularly finding these problems where the original building is being extended or altered. This could be a single storey rear extension, a two storey extension or a loft conversion/extension. When we carry out these defect reports we utilise a variety of instruments including

1930'3-1950's floor plan

1.  Thermal imaging cameras

2.  Gann resistance meters

3.  Surface temperature readers

4.  Relative humidity readers

5.  Data collectors

Thermal image of a window frame The blue is the colder area and the red is the warmer area

The basic problem with this era of house is that we are trying to live in a house that was built in the 1930's to the 1950's in a modern way and as such we have modern requirements of the house. It was a very different world when the houses were originally built, during or at the end of the War Years, and basic considerations such as being able to source the right materials to build the houses were upmost in the developers, architects and builder's minds. The houses were very much the best that could be built during this time and the fact that we are still living in them is testament to how well they were built. However we are now having problems with them while living in and using them in a modern way.

House built between 1930 and 1950

Many metal single glazed windows have now been replaced with plastic double glazed windows, with and without trickle vents.

The reason the metal windows were replaced was that many people became very fed up with these windows as they were prone to considerable condensation. This is because as the warm air came in contact with the cold metal of the window condensation occurred.

Horizontal sliding sash

At first new double glazing was made using Aluminium and some of these may still be around in properties from the 1930's, 1940's and 1950's. Although these were a great step forward they still created a lot of condensation because of the problems with the coldness of the metal.

After this we progressed onto plastic windows which were of poorer quality and had a limited life. Modern plastic windows now have trickle vents as we have decided to add ventilation back into the windows to help reduce the problems with humidity. More about humidity in a second!

As mentioned earlier another popular feature of this era of property was the semi-circular bay window which developed from previous eras and generations of windows such as the Victorian and Edwardian. These were lightweight, usually without foundations and sometimes clad with vertical tiling They would also originally have been built with next to no insulation but may have had insulation added later.

1930's property. Bay window with vertical tile cladding and aluminium windows

A lot has been said about rising damp. Many property owners, when looking at buying a property, are put off if, after having a survey carried out, they hear there is rising damp. A very big problem with rising damp is that it is often not actually rising damp at all. It can be anything from leaking gutters to capillary action caused by render bridging the original damp proof course or humidity within the building.

Damp patch to the ceiling

Damp patch half way up the wall

Damp patch at the bottom of the wall

We think this because we see many damp buildings. In fact of late we have been seeing damp problems every week. We tend to find that the older buildings that were designed before insulation was thought about and traditionally get rid of water by drawing it in then releasing it gradually, known as breathing, can no longer cope with the amount of humidity in the air.

Dampness and old buildings

Sloping ceiling

A thermal image of the walls and the ceiling. The blue shows that the ceiling is cold where it's part of the roof

Often there is very little consideration given to how a house works and how it will work when old and new construction come together. This can result in dampness approximately where the two constructions meet. The two buildings work very differently, the modern one having a cavity wall and usually dry lining and the older building having solid walls often in Flemish Bond brickwork or possibly even render

War Years property extended (red circle) and altered with plastic double glazing windows (green

1930's property extended to the rear

1950's property roof conversion

We have seen modern renders and modern paints cause problems. We term them as plastic or polymer paints and these are paints that seal a building.

Ironically these paint and render finishes are advertised as maintenance free when unfortunately they are often a contributory fact towards dampness in a building.

Modern render with plastic paint can cause dampness

Unfortunately we would say that the jury is still out and we are still learning and understanding how buildings work when they are super insulated which is what we are doing today with our houses. We are producing airtight boxes in which any heat that is created stays in there for a long time. This works where the whole building is new but where it is part old and part new we find it tends to have problems.

Black mould

We hope this article has opened your eyes to condensation, humidity and black mould. We believe this is a big problem and can have effects on your health and is generally not a good environment to live in. If you can possibly change it or improve it then you should.

Black mould