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8 Causes of Rising Damp

As the weather begins to cool down in Perth, it’s a good time to start preparing for the rainy season. That might sound a bit dramatic — we’re not expecting any monsoons — but poorly waterproofed area can lead to significant, costly damage in your property.

Whilst wet-areas, like bathrooms, are the obvious place to think of when we mention waterproofing, in winter, we want to consider balconies. This is especially true when it comes to older properties that have seen a bit of wear-and-tear. When it rains, improperly waterproofed areas can lead to expensive water penetration and leak issues such as flooding, concrete cancer, and rising damp.

What to look for

It’s easy to jump into rising damp solutions and fixes, but if you don’t know what’s causing it in the first place, an act-first-think-later approach will do more harm than good. To truly solve rising damp and stop it from returning, it’s vital to uncover its cause. But, with eight possible reasons that all have the same major symptom (rising damp!), getting to the damp’s beginnings is easier said than done…


​​1. Porous limestone & brickwork 

Limestone footings soak up moisture at the base of a wall. If exposure is restricted, moisture will travel to the next driest material — external and internal leafs of brickwork — which sometimes sit directly on the limestone. Porous brickwork and mortar soak up moisture from the ground, footings, reticulation or rain, which travel through the wall and damage internal and external wall finishes.


2. Inadequate drainage & air vents

High moisture levels often come from a lack of wall drainage or ventilation. Without air vents or anywhere to drain, moisture penetrating the external leaf will build up in the cavity. This moisture comes into contact with the internal leaf, making the internal brickwork moist, damaging internal finishes (in other words, rising damp inside the home). This is where air bricks come in. Made from cement, plastic, or metal, they’re the same size as the common house brick and have holes in them for ventilation, allowing moisture to escape.


3. No waterproof coatings or barriers

When the external ground level is higher than the internal floor level and no waterproof barrier exists (or it does, but is faulty), water can penetrate the brickwork and travel to internal walls. Because bricks are porous, water hitting a property's weathering side can soak into the wall, flow down, and rest at the wall's base. Even with the right drainage, this eventually builds to rising damp, which is why, professional waterproof coating is essential.


5. Single–leaf construction

Where there is no air cavity within the wall, there’s nothing to prevent moisture penetrating the inside from external surfaces. All modern homes are double-brick (also called cavity-wall or double-leaf) to help prevent this. If your property it older, you may be seeing rising damp due to single-leaf construction.


6. Damaged mortar joints

Missing, worn, or cracked mortar in brickwork allows water to easily penetrate the surface and get into the internal leaf. Luckily, poor mortar condition is usually easy to spot, so this problem can be fixed before it even leads to rising damp — if you get onto it quick enough.


7. Movement cracks and fractures

Ground movement can cause cracks and fractures from the footings to the walls, creating moisture passages. These commonly occur with nearby construction groundworks, for example, a new building development next door. The good news is, like damaged mortar, factures along the wall are usually obvious, and can be fixed before water damage and rising damp becomes an expensive fix.   


​8. Damaged tiles and grout and no, or faulty, waterproof membrane beneath tiles.

Inside, it is absolutely essential to have effective waterproofing in wet-areas underneath tiles. When water escapes through damaged grout, tiles, or poor waterproofing, it can cause serious structural damage. Aside from leaks and rising damp, the damage is particularly dangerous for concrete substrate (which leads to devastating concrete cancer).

We're Perth's rising damp experts

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