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Property Surveying Blog

August 29, 2016

Damp in Properties

Written by Berry Lodge Surveyors

Here at Berry Lodge Surveyors, although we specialise in Party Wall Surveying, we are also Chartered Surveyors. This experience means that we are regularly confronted with property defects that the average homeowner may overlook.

By far one of the most common defects our surveyors regularly see is damp.

Dampness within any property can be a worrying time for both tenants and owners. Not only can dampness cause health problems, it can also lead to structural issue and if left untreated and after prolonged exposure, in extreme circumstances, structural failings can occur.

Given the cost implications of both identifying damp and then treating it, we thought it would be helpful to write a short blog post on the topic so that you can hopefully identify it and take the necessary actions to eradicate and deal with the issue.

Condensation to a bedroom

One of the most common misconceptions our surveyors see, is that condensation within a property is a form of damp.

While condensation can be a result of a poorly insulated property, most commonly condensation is due to poor room ventilation, with the culprit rooms being kitchens, bathrooms and bedrooms.

You will often find that condensation always occurs to those rooms where the moisture content in the air is at its highest and the ventilation is at its lowest.

Condensation is formed when warm or hot water vapour comes into contact with a cold surface. For example, when showering, water droplets will often form on the ceilings and tiled walls nearest the shower and often furthest from the ventilation. If this condensation is left untreated for a prolonged period of time, it can lead to mould growth that is often mistaken for damp.

Damp can generally be categorised into two main types:

  • Penetrating Damp
  • Rising Damp

So let’s look at the differences between the two;

Penetrating Damp

As the name suggests, this form of damp moves through the walls, in a direct front to back manner. Penetrating damp can be caused for an almost endless number of reasons, however in our experience we find the following causes to be the most common.

Penetrating Damp

Failure of mortar, or cracking to the brick face:

This allows rainwater to enter the external walls via those defects which act like capillaries, drawing moisture into the wall leading to unsightly damp spots. We find that this type of damp is most prevalent in solid construction, single skinned walls.

Bridging of a Cavity Wall:

Again often caused by a number of different defects, however believe it or not, this often comes down to poor work practices during the construction phase.

Over the years we have seen all types of objects within the cavity of a cavity wall, from planks of wood, to coffee cups and even a discarded broom stick.

These items, strange as they may be, all lead to the transfer of water from the external wall to the internal wall and after prolonged exposure, all lead to some form of decorative internal damage.

Leaking of Internal Plumbing:

Another of the most common causes of damp we regularly see is old, or poorly fitted pipework gradually leaking within a cavity wall, suspended floor or ceiling.

Given the speed at which the leak occurs and the gradual nature of the defect, a small spot can slowly grow to a stain, which in turn grows to the point where the wall becomes saturated and the plaster starts to blister or sag.

So now that you have an idea of what to look for when it comes to Penetrating Damp-Let’s take a closer look at Rising Damp.

Rising Damp

Unlike penetrating damp, rising damp will always originate from the ground and moves from the lowest part of the wall, upwards, in extreme cases reaching heights of 1m above the source of the damp.

It is important to add at this point, that in all of our surveyors’ combined years of experience our surveyors have never actually seen a case of rising damp and in 99% of cases, it is almost always penetrating damp.

However, that being said, our learned experience tells us that rising damp can be most prevalent in houses with the following defects;

Bridging of the Damp Proof Course (DPC): A damp proof course is a protective barrier that is inserted into the external wall of property to stop water rising up and penetrating the walls above it.

Historically in properties built around the turn of the century, the DPC was a slate tile laid flat and bedded between the brickwork. However, these days DPC’s tend to be thick polythene or similar plastic materials.

Given that the bridging of the DPC only takes place as a result of some form of water penetration, it is for this reason why in our experience rising damp is a most commonly a myth!

When patios, pathways or garden ground levels are raised too close to an external wall, they all allow water to splash or penetrate above the DPC and thereby lead to penetrating damp and eventually internal damage.

If you are one of the many people whose home suffers from damp, you will be well aware that it can be very difficult to get rid of. In the event that the issue has manifested itself on a Party Wall, treating it can also become a matter that will have to be dealt with under the Party Wall etc. Act 1996.

This could mean that you not only have to go through the procedure of eradicating and treating the damp, you will likely also need to go through the necessary Party Wall Agreement procedures.

Injection Damp proof course

An example of works related to damp, that would be notifiable under the Party Wall etc Act 1996 would be an injected chemical damp proof course.

A chemical damp proof course is physically injected into the mortar or brickwork, effectively making a water repellent barrier to stop any damp from rising upward through the wall.

If you have any questions regarding damp or are perhaps about to undertake construction work on a wall which is suffering from damp and would like to see if the Party Wall etc Act 1996 aplies, feel free to give one of our Chartered Surveyors a call, we are always on hand and happy to assist you.