Rising & Penetrating Damp

Is it Rising or Penetrating Damp?

We have all experienced condensation or damp in our properties at one time or another. Residing in a home with dampness present can be risky for the health of everyone living in it. Dampness in a property can come from all sorts of sources. It is crucial that you understand how the property is constructed, especially with older buildings. Damp can lead to issues with the property if not treated, which is why it is essential to address the issue as early as possible. The longer the issue remains untreated, the problem will surely worsen resulting in much more expensive repairs and even replacement.

Determining whether the problem is rising or penetrating damp is critical. The misdiagnosed damp issue will result in ineffective damp proofing treatment and measures.

These salts will cause the paint to bulge or bubble with fluffy white deposits on the surface. There are two types of salt involved – hygroscopic salts (nitrates and chlorides) which draw moisture continuously and should be treated immediately, and sulphates which cause the white crusty patches on the wall.

Rising damp is often misdiagnosed and confused with condensation, but there is a way to identify them correctly. The most reliable way to discern between rising damp and dampness due to condensation is to compare moisture content in the masonry or mortar. If the inside of the wall is damp, it is rising damp. An electrical moisture meter can be used to identify the moisture content. Rising damp can rise up to 1.5 metres or higher in rare cases.

What are the Causes Rising Damp?

Rising damp is only limited to ground floor levels, wherein the moisture from the soil permeates up the wall. The damp-proof membrane or damp-proof course is a barrier installed in the walls that inhibits the moisture from going up further. Modern properties most likely have the barrier installed but it may not be present in older buildings. If the damp-proof course is faulty, damaged or missing, the property is susceptible to rising damp. Rising damp also happens when the ground level outside is higher than the floor level inside the property. Rising damp is not always caused by outside sources. For the past 20 years, condensation has become the most common factor that produces rising damp in homes as well.

What are the Symptoms and Signs of Rising Damp?

Rising damp starts to form mould growths in timber, which causes it to rot. Green, white and black mould growths are present. Deterioration of paint and blistering or peeling of wallpaper are also indications of rising damp. Dark patches that are damp to touch can be an obvious sign as well. Outside walls may have discolouration. Salt stains begin to show up on the walls and the mortar may break. Rising damp can also cause iron and steel fasteners to rust. If the occupants of the building start to have respiratory illnesses, rising damp is likely the culprit due to the musty smell and spores from mould build-up. In severe situations, the affected wall may cause plaster or mortar to fall away and deteriorate. Rising damp can also cause tide marks, crumbling skirting boards and powdery, white substance on floors and walls (mineral deposits).

A damp-proof course can also be installed to prevent the moisture from rising further. The barrier can include pore blocking salt mixture, water repellent chemicals and osmotic water repellents. If the damp-proof course or damp-proof membrane is faulty, you can replace them. Another solution is tanking the walls, which means the wall is given protection from moisture by sealing it.

• Lateral Penetrating Damp typically takes place on external walls where the level of the external ground is higher than the floors inside the property. A perfect example of lateral penetrating damp is the basement.
• Vertical Penetrating Damp is caused by defects in the building and its poor maintenance. Some of the most common causes of vertical penetrating damp are blocked downpipes and guttering, roof defects, defective rainwater goods and leaking. These are also responsible for the occurrence of dry rot.

What are the Causes of Penetrating Damp?

Penetrating damp is typically caused by structural issues in a property or building, like defective brickwork, faulty roofing covering or guttering, defective joints between walls and windows, leaking rainwater pipe, and crack on the walls. Internal leaks can also aggravate penetrating damp (e.g., pipes found under the bath or sink). Pointing, brickwork and render can be deteriorated with frost, age and physical damage. The absence of any form of waterproofing system will also cause penetrating damp.

Penetrating damp is an indication that the roofs or walls are frequently soaked with water. Penetrating damp below ground, on the other hand, is caused by water from the ground that seeps into and out the masonry.

What are the Symptoms and Signs of Penetrating Damp?

• There is ingress of water.
• Damp patches which can be found on ceilings and walls. These patches may darken when raining.
• Circles of damp that increase in size found on walls or ceilings.
• Uneven patches found on walls.
• Crumbly and wet plaster.
• Puddles and drips.

What are the Most Common Areas that Can be Affected by Penetrating Damp?

• Window Frames. These are inspected for the presence of cracks or gaps around the frame. These gaps and cracks will let the water come in and cause dampness.
• The Roof. Look for the tiles, roof ridges tiles, pointing and flashing. If any of them is loose or missing, maintenance is needed to prevent penetrating damp.
• External Walls. Look for pieces of mortar that are missing and the presence of cracks in the masonry. If they are observed, they can be repaired with the correct filling material to prevent penetrating damp.
• Door Frames. Look for cracks around the door frame and repair them if present. Look for the presence of a weather bar as well, as it helps in preventing penetrating damp. Install a weather bar if there is none.
• External rainwater downpipes, gutters and drains. Check them for cracks or leakage. Damage in the rainwater goods can be a source of penetrating damp.

How is Penetrating Damp Treated?

The most important thing to do is to get rid of the main source of moisture by inspecting every area in and around the building. Look for defects in the gutters, flashing, downpipes, window frames and rendering. Make sure that the gutter is free from obstruction, but if it is, consider replacing the guttering. If you find any gap around the window frame, you can seal it. You can also remove any debris in the cavity wall if you find any. The debris acts as a bridge for dampness from the outer wall to the inner wall of the property.

The waterproof coating could also be used on the external wall. The coating will form an impenetrable barrier against moisture and it will repel water as well. Fungal growth can also be prevented by the said coating.

For penetrating damp below ground, treatment is a little bit more complex. It is best if you hire a professional to do the job. An expert will apply a cementitious survey or plastic membrane in the masonry.

Seeking help from an expert will ensure that your damp problem is dealt with properly and professionally, resulting in the application of the right damp proofing treatment.

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