What we do
What is damp proofing?
Damp occurs for several reasons.
Rising damp
Damp Proof Course (DPC) is a waterproof barrier that is placed in external walls approximately 150 mm above the ground and just above the ground level in internal wall structures. A DPC is designed to prevent rising damp occurring.
However, if the DPC has been damaged or deteriorated, has been installed incorrectly or is non- existent, rising damp can occur. Rising damp can affect interior or exterior walls.
If the DPC is not working as a barrier, moisture in the soil will be absorbed up by means of a phenomenon known as capillary action where moisture defies gravity and travels upward from the ground into the porous brick and mortar structures of the walls to a height of approximately 1 m above the ground.
This moisture then dries out, impacting the paint and plaster on the wall negatively. Negative impacts can include paint bubbling or blistering, crumbling or powdering of the plaster, efflorescence deposits (white powdery deposits left on the wall, commonly known as salts), discolouration of walls, mould growth as well as rotten/warped wooden skirtings.
A combination of moisture and salts is the primary causes of paint and plaster failures.
Capillary action will remain constant in the brick work unless addressed. The long-term impact of rising damp could lead to structural damage and reduce the value of the property. Damp can also lead to health issues of the occupants of the house.
Lateral damp
Lateral damp is the transportation of moisture through absorbent wall structures horizontally due to the bridging of the damp proof course (DPC), porous brick and mortar or cracks which will result in the occurrence of damp patches, paint bubbling, powdering of the plaster, soluble salts deposits or paint discolouration on the internal wall. A tell-tale sign of lateral damp is a small amount of dust on the floor below the damp in the room. Unlike rising damp, lateral damp can be found at any level on the wall.
If left untreated lateral damp can lead to structural damage. Electrical damage could also be experienced in electrical sockets.
Health issues have also been linked to internal damp.
Penetrating damp
Penetrating damp is the ingress of moisture into a structure through voids such as hairline cracks, cracks between window frames and brick work, cracks in walls which allow moisture entry and cracks in window ledges.
Penetrating damp can also occur in cracks in roof tiles or roof ridge capping or through roof bolts on metal roofs.
Balcony decks or above ground level showers that have not been waterproofed or waterproofed adequately can also sustain penetrating damp.
In areas where water ingress through the tops of walls that have not been waterproofed or where the routine maintenance has not been kept up could also be subject to penetrating damp.
Corrective action for penetrating damp is usually resolved by waterproofing technologies.
Defective plumbing
Defective plumbing can create visible damp on walls or ceilings at any level. These include leaking water or plumbing pipes in walls or ceilings, a leaking geyser, a leaking toilet. A plumber needs to rectify the problem before damp proofing of the walls or ceiling can take place.
Condensation
Condensation is the build-up of moisture in a closed area where there is a lack ventilation or poor ventilation in the area. Common areas for damp created by condensation include the bathrooms, kitchens, tool sheds, garages that are sealed from all air flow,
What is mould?
Mould is the common term for fungi. A microorganism which includes approximately 300 000 different species. It will show on surfaces as patches of black, green, brown, yellow, or pink. Often accompanied by an unpleasant, lingering odour.
What causes mould?
Mould spores are invisible to the naked eye and float through the air. Growing when a spore lands on a moist surface, preferably in a dark place. To grow, mould needs mould spores, a food source (e.g. wood, plaster, cotton), darkness, warmth, and oxygen. Excess moisture is the key contributing factor for mould growth as the others are usually always present in a building. Whether that be your home or place of work.
It is important to remember that a certain degree of moisture will always be and should be present in the air. For year-round comfort, it is recommended that humidity levels sit circa 40%. Too much or too little can have a significant impact. Not only on your health, but the health of the building too.
There are various ways to increase and decrease humidity levels. A damp and moisture survey can help you identify the current humidity levels within your property.
The most common causes of mould
There are several ways that excess moisture could be getting into your home, or even your workplace. The four most common types of damp include rising damp, penetrating damp, damp caused by defective plumbing and damp caused by condensation.
Rising damp
Rising damp occurs when the water on the ground level rises into the house or building. Having bypassed the damp proof course – a layer of waterproof material in the wall of a building near to the ground.
This form of damp will not usually rise above 36 inches from ground level. Therefore, it usually only affects basements and ground floor rooms. With the trademark of a “tide mark” low down on the wall, rising damp often leaves a white mark. This is a result of the salt contained within the water.
Mould does not usually accompany rising damp as the salt prevents it from growing. However, if left untreated, it can cause other issues such as cracked plaster and lifting wallpaper.
Penetrating damp
Found exclusively on external walls and ceilings. Penetrating damp is caused by water passing through a building defect such as a missing roof tile or pointing. It will be most evident after rainfall and will appear as an obvious damp patch. This will dry out as the weather improves.
As the water can pick up salt as it passes through the building material, mould will rarely grow because of penetrating damp. Much like with rising damp, if there is any salt present, this will stop the mould from being able to grow.
Defective plumbing
Whether it’s a leak from the toilet, shower, sink or a pipe, defective plumbing can affect internal walls and ceilings. Appearing as an obvious damp patch, damp from defective plumbing will appear no matter the weather outside. However, it may get worse after a certain utility is used. Such as the shower is turned on or the toilet is flushed.
Although rare on larger leaks as the area will be too wet and wastewater is generally poisonous to mould, it can appear if left untreated. Rot in wooden joists and floorboards is also a risk of leaving a plumbing defect untreated. Which, in severe cases, can lead to them collapsing.
Condensation
The most common cause of mould is condensation. Water which collects as droplets on a cold surface when humid air is in contact with it. Think of those cold mornings when your heating is turned on and how much water is sitting on the surface of your windows. Condensation is most found on or around windows. Especially during the winter, but also regularly grows within the corners of a room and on north facing walls. It can even be found behind large objects such as beds and wardrobes. In areas that do not get much ventilation – especially when up against an external wall.
There are many contributing factors to condensation, and many are a result of lifestyle. From simple actions such as boiling kettle or drying clothes indoors, there is a lot that we do every single day that adds to the amount of moisture in the air.
Mould is almost always seen with this type of damp and is often the hardest to remove as the cause (i.e. lifestyle) is not usually adjusted once the mould has been removed, resulting in it returning again and again.
If you want to get rid of mould, first you must get rid of the excess moisture.
