Damp Forms - Rising Damp, Penetrating Damp, Lateral Damp & Condensation

Important Damp Information to Remember...

There are many forms of damp that can be found in a property. Different types of damp require different forms of damp proofing. As a result, it is highly important that a specialist damp and timber surveyor carries out your survey to ensure that the correct form of damp is diagnosed. Damp in buildings can become apparent in different forms such as; rising damp, penetrating damp, lateral damp and condensing damp (condensation). A correct diagnosis will save you money on unnecessary damp proofing along with the inconvenience of remedial works.

Damp Pro damp surveys are carried out a fully qualified independent remedial surveyor who is a specialist in rising damp, penetrating damp, lateral damp, condensation and all damp proofing treatments.

What is Rising Damp?

The symptoms of rising damp are a natural phenomenon which occurs with the upward movement of capillary moisture (damp).

This moisture is carried up through the pores of masonry via capillary action. This moisture carries damaging hygroscopic salts from the ground (earth) such as nitrates and chlorides which are commonly associated with rising damp. Once the moisture reaches its maxium height in rise the moisture will start to evaporate to the surface contaminating the plasterwork with hygroscopic salts.

Hygroscopic means the ability to absorb moisture from the surrounding environment in plain english becomes soluble to high humidity. Thus, giving the damp feel you get when you touch the wall.

Rising Damp is a problem that affects many properties not only in the UK but all across the world.

How high does rising damp occur?

The height of the upward movement of capillary moisture depends on the size of the pores in the masonry. For example, the masonry with small pores has the ability to have a greater height difference in rising damp than masonry with larger pores.

The movement of rising damp in a wall is best described like a candle wick in oil, absorbing oil from the bottom and progressing up the wick. This is similar to the capillary action for rising damp.

Moisture progresses up the wall via capillary action through the pores of the masonry mortar joints and any cracks. Once this moisture has peaked to its maximum height (usually 1 meter but not uncommon to reach 2 meters in rare cases) the moisture begins to evaporate through the plasterwork, which migrates damaging hygroscopic salts (nitrates and chlorides) into the plaster work.

These salts that are commonly associated with rising damp, become deliquescent (soluble) when in contact with high levels of humidity. Thus, on days of high humidity or after cooking and bathing the damp problem can become much worse. This is where you get a damp feel to your plasterwork and/or peeling of wall paper because the glue has become soluble again and detached from the damp wall.

Does Rising Damp only affect external walls?

This is a common question our remedial surveyors come across when they carry out damp surveys. The answer to this question is NO. Rising Damp can occur on an internal or an external wall as long as the walls are abutting the ground at the substrate where there is a breakdown of an existing damp proof course or no damp proof course at all.

The Introduction of the Damp Proof Course

In 1875 a new government legislation was introduced; Public Health Act of 1875. This Act prevented the construction of buildings without a damp proof course (DPC). Slate damp proof courses were commonly used at this time as slate was durable and easy to get hold of being a local resource in Wales.

In the 1960’s new builds had to be built with a damp proof course membrane (DPM) in situ in the solid floors. So as the years have gone on it has become compulsory to install physical damp proof courses and damp proof membranes in all properties in the UK.

However, the presence of a physical damp proof course or damp proof membrane does not guarantee that rising damp will not occur. The damp proof course may be continuous, but may have defects such as bridging and/or cracking due to its age.

How do you treat Rising Damp?

Before rising damp is treated you have to make sure that the damp ingress is actually rising. A specialist damp survey will determine this. Once all other sources of moisture have been eradicated, rising damp can be treated in many ways such as Chemical Damp Proof Courses, damp proofing injection mortars, electro-osmosis and many more thatare available to us depending on your budget and needs.

Which damp proofing solution is right for me?

This might be the question you are asking yourself, and will depend on the situation your property is in, whether or not any other factors may affect certain damp proof course systems. The best way to put your mind at ease is to have a specialist damp survey carried out to diagnose rising damp correctly and to recommend the most practical solution and cost effective way totreat the rising damp problem.

Lateral Damp

What is Lateral Damp?

Lateral Damp is very common in basements and can affect ground floor walls with high external ground levels. The damp ingress is due to the lateral movement of moisture from the ground (earth) outside. The moisture penetrates the masonry, migrating damaging hygroscopic salts (nitrates and chlorides) from the soil to the plasterwork and masonry inside. This can give you similar symptoms that are associated with rising damp. However the treatment for this damp ingress is rather different from the treatment of rising damp (damp proof course).

How do you treat lateral damp?

Lateral damp can be treated in many ways, with plenty ofoptions available on the market today. Some of which are cavity drainage systems and Vandex BB 75 systems which are commonly used for basement waterproofing. However, to determine which system is suitable for your lateral damp problem, a damp survey is required which will determine the most cost effective system for you and your property.

Penetrating Damp

What is Penetrating Damp?

Penetrating damp in most commonly associated with blocked, broken or incorrect installation of guttering, valley gutters, roofing, parapet walls and lack of bellcast drip beads etc. This can be misdiagnosed as rising damp in the wrong hands and can cost you hundreds even thousands of pounds of unnecessary damp proofing.

How do you treat Penetrating Damp?

Quite simply...Locate the source of moisture and eliminate it, give it a chance to dry out, and then determined whether any replastering is necessary after a drying out period. However in some cases the damage has gone too far and the plaster work has gone past its sell by date. Our surveyors will determine whether this is necessary, however 9 out of 10 times, replastering is not needed and certainly no damp proof course is necessary.
Something important to remember though is depending on how long the damp penetration has been going on, will depend on the extent of the damage. Sometimes this minor problem can lead to bigger problems i.e. wet rot to floors, joist ends, rafters. However, it isnot uncommon tofind that Dry Rot has developed from the source of the moisture.


Condensation is one of the UK’s most common damp problems and is most common in the winter months, causing black mould and water droplets to condense on your walls and windows.

What is condensation?

Condensation is a build-up of humidity in a property caused by cooking, bathing and drying clothing indoors. All these factors increase relative humidity in the property and once this humidity cools below dew point, will then lead to the condensing of moisture on any cold surface. If left untreated,this moisture will then lead to black/green mould appearing where the moisture condenses, leaving you with a musty damp smell along with spoilt decoration where it forms.

How do you treat condensation?

Like above, it must be correctly diagnosed and once done so it’s a tricky one to combat, however with the expert knowledge and right know-how can be easily remedied, in the form of specialist easy to understand advice from our surveyor, anti fungal wash downs and the correct installation of air vents. Condensation can be an inexpensive problem to combat if done correctly, saving you money on running dehumidifiers and unnecessary damp proofing treatments. One thing to remember, is that too many air vents can actually make the problem worse so we recommend you seek our specialist advice before installing air vents to every room in your property because this may cause more problems.