Damp In Freestanding Walls

Do Your Boundary Walls Look Like This?

This photo I took during a client’s comprehensive buyers inspection had rising damp, falling damp and penetrating damp in the boundary and garden walls. In addition, the white marks on the wall were caused by efflorescence.

Often the maintenance of the walls that are attached to or which do not form part of our houses is neglected. These are our boundary, garden and courtyard walls.

These walls are very important in that they protect our privacy and security and are our first line of defence against intruders. Unfortunately, we sometimes do not make enough effort to protect them!

The greatest enemy of these walls is damp which penetrates into the wall from below, above and from the sides of the walls.

Rising Damp

Rising damp occurs as a result of capillary action at and below ground level into porous building materials. These materials are mainly concrete, bricks and mortar. The moisture rises up the wall in this way. It usually occurs where there is no damp proof course (DPC). Freestanding walls such as boundary and garden walls do not normally have DPC built into the walls because it would make the wall unstable. A layer of DPC would break the bond between the wall and its foundation.

The height to which the moisture will rise is determined by the evaporation rate and the nature of the wall. However, the normal limit for rising damp is generally about one metre above ground level.

Rising damp may show as a stain on the plastered and painted wall, the blistering of paint and loss of plaster. A damp area may be evident at the base of walls and in extreme situations, may cause the structure of the wall to wear away and crumble.

Falling Damp

Falling damp is caused by downward water penetration from the top of porous masonry walls. This is as a result of the top of a boundary wall not being adequately waterproofed, if at all.

Walls should be:

properly sealed at vertical expansion joints;
repaired at copings that have cracked or deteriorating mortar joints;
cleaned to prevent the build-up of dirt and moss on upper surfaces of stone or brickwork.
Leaves, bird manure, moss and dirt on top of the walls contain weak acids and salts which can promote decay of the masonry and paint if absorbed.

Penetrating Damp

Penetrating damp is a common form of damp. It occurs as a result of the horizontal ingress of water through gaps, cracks and joints in the wall’s structure. Penetrating or horizontal damp can be due to your or your neighbour’s irrigation system spraying against the boundary wall. Moreover, foliage growing against the wall (bushes and trees)can also be the cause. Other causes are deteriorating paint finishes and inadequately ruled joints which allows moisture intrusion into faced brick or stone walls.

Penetrating damp tends to produce localised patches of dampness and decay, whereas rising damp may affect the base of the wall.

Efflorescence

Efflorescence occurs when an appreciable quantity of soluble salts and moisture is present in the masonry. It routinely occurs in masonry construction, particularly in brick and concrete. It typically occurs during the initial curing of the cementitious product. Moisture carries these salts to the face of the masonry or concrete where the moisture evaporates.

As the water evaporates, it leaves the salts behind as a white fluffy deposit. Therefore, to remove it, brush the deposit off when the wall is dry. It usually disappears with time after rains or washing with water.

Efflorescence is generally an aesthetic concern and not a structural one. However, where there is excessive efflorescence, the crystallizing salts within the pores of the masonry can disrupt even the strongest material. As a result, this can lead to the breaking up and crumbling of the structure.

How to prevent damp damage in your freestanding walls

Rising Damp

Rising damp is not easy to resolve in any freestanding, boundary or garden walls because of the lack of DPC. However, you can do the following:

Make sure that there is no pooling of water against the wall. Good drainage away from the walls is essential. If you have a low point in your garden against your boundary walls you will need to create a hole in the wall at the lowest point for the stormwater to drain away. Your neighbours have to accept a certain amount of your stormwater by law.
Try not to overwater your gardens against boundary and garden walls. overwatering will result in sodden earth around the walls and, as a result, rising damp in the wall.
Keep leaves and other debris on the ground which may retain water away from the walls.

Falling Damp

You should waterproof the tops of all freestanding walls with a layer of an acrylic waterproofing system or any other system to prevent moisture intrusion into the top of your boundary and yard walls.
If there is a concrete or brick coping on top of the wall you must ensure that the joints form a water-resistant seal. You should seal all deteriorated joints or porous joints between the bricks and copings.
Seal the top of expansion joints to prevent water from entering the joint with a silicone sealer.

Penetrating Damp

If your freestanding walls are plastered, check the paint finish regularly. It may be time to repaint if the finish is chalky.
If you have a sprinkler system make sure that you are not watering your boundary walls. Sprinklers heads are normally adjustable. If yours are not, change them.
Trim bushes and shrubs so that there is a gap between the foliage, branches and the walls.
If it appears that the moisture is from your neighbours’ sides, you will need to talk to them about the problem.
Clean out and seal vertical expansion joints with a good silicone sealer. Any cracks should be sealed as well. Furthermore, if your plastered walls are covered in crazing cracking wash the wall down. Thereafter, when the wall is dry, seal the wall with a sealer and repaint the wall.

Efflorescence is a sign of damp

Efflorescence is caused by moisture absorbed in the wall evaporating and leaving behind salts as a white powder. Therefore, if you repair and maintain your walls as suggested above, very little efflorescence should appear on your walls.

I am not specifically promoting Prominent Paints as all the well-known paint manufacturers produce the same required paints and sealers. You can use most of them to repair and maintain your freestanding walls.

However, Prominent’s video provides very good advice on how to repair moisture damage to boundary and garden walls!

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THE HOME DETECTIVE » maintenance defects

30/01/201924/03/2022

High Water Bills

MY WATER BILL WENT WAY UP! HOW DO I FIND A LEAK?

Your high water bill could be due to either a temporary increase in water usage or a leak. To find out if it’s a leak, first shut off all your water-using fixtures in the house. Don’t close the shut-off valve where the water supply enters or below the pressure regulator at your house at this stage!

Take the cover off your water meter box and flip open the protective cover plate on the meter dial. Normally, your metre box will be somewhere along the front property line, often near a corner. You may have to dig down a little in the dirt to find it.

The meter may be a newer one that has a small round or diamond-shaped low-flow indicator near the centre. The low flow indicator may be red or black like in the photo above. It should not be turning. But if it is, there’s a leak somewhere in your plumbing system. At a meter without a low-flow indicator, note the meter reading or take a picture with your cell phone. Check back in an hour or so and see if it has changed.

There are a number of places to check if the meter says you have water flow indicating a leak:

1. Taps

Not just the at the sink and basins taps! Also, check the taps at the washing machine hookup, bath, shower, and the outside hose taps.

2. Toilet Cisterns (tanks)

A flapper valve that doesn’t seat properly at the bottom of the cistern will cause a leak. Check the ballcock arm and overflow tube as well, it may also be defective. Drop a dye tablet (available in most hardware stores specifically for toilet testing) in the tank. Do not flush, and wait for 15-minutes. If the colour shows up in the bowl, the toilet needs repair.

3. TPR Valve at the Geyser

The small valve with a flip-up handle at the top or side of the geyser called a Temperature and Pressure Release (TPR) valve. This important valve is designed to open if the water gets too hot, to keep the tank from exploding. These valves sometimes fail by opening slightly and letting loose a slow trickle of hot water. The water normally runs in a steel or copper pipe to a location at the exterior wall. Find the termination of the TPR valve and check for a drip. NEVER work on these valves yourself! Only a suitably trained and experienced plumber should!

23/01/201925/09/2023

Efflorescence

WHAT ARE THOSE POWDERY WHITE AREAS ON MY BRICK WALLS?

Efflorescence is an eyesore! This is the presence of the white powder that forms on the face or surface of concrete, plasterwork and brickwork. Blooming or flowering are other names for efflorescence.

It is a cause for concern!

Efflorescence is a build-up of minerals and salts staining the surface of the concrete, brick and plasterwork due to repeated bouts of excess water in the material. The minerals and salts that naturally occur in the material are dissolved when the brickwork, plasterwork or concrete is waterlogged with water.

Concrete, pavers, brickwork and plasterwork are porous and can absorb or wick water and draw salts to it like a tree transports water from its roots to its leaves. This is capillary action. When efflorescence or blooming happens, it can indicate a moisture issue that could potentially damage the structure.

When water reaches a building material’s surface, evaporation will occur. Water absorption and wicking will continue after the water evaporates and the salt is left behind looking like flowering or blooming. This eventually creates a high salt concentration, leading to osmosis.

What is Osmosis

Simply put, osmosis in building materials is the movement of water from a region of low salt concentration to a region of high salt concentration in the material.

During osmosis, water moves toward salts and minerals to reduce its concentration. It can cause large hydrostatic pressures within the porous building material. As a result, these pressures can damage or destroy the material.

Osmosis can cause pressure that ranges up to 200 bar, exceeding the structural strength of concrete or brickwork. As a result, osmosis may result in porous building material staining, cracking, flaking or falling apart.

13/01/201924/03/2022

Sealing at Windows and Door Frames

Detecting Leaks Around Your Windows

Seals that are broken, pulling away, missing or which are damaged as a result of ageing or long-term weather exposure will cause windows and doors to leak. Furthermore, the sealant or window putty used to seal the glazing beads on wooden windows may crack and allow moisture into the gazed areas of your windows. In addition, when the glazing putty on your steel windows cracks or a section falls out moisture will corrode the steel window frame.

These are the most obvious areas where leakages occur!

However, the most undetected area for leaks at windows is the junction between the window frame and the brickwork, plasterwork and window sill. As a matter of fact, it is one of the most common defects that I have found in both new and older homes.

There are multiple ways to detect leaks around your windows and doors:

On the outside of your home, check the areas where two different materials meet. This includes your door and window corners and frame.
Look for cracks in the door itself and in window panes.
Examine the existing caulking (sealing) and window weather stripping and weatherboards on doors. Make sure both are in good condition. In addition, leave no gaps or cracks.
If you can see daylight around a window or door frame, there will be a leak.
Shut a window and check for gaps in which you can insert the paint scraper. If you can easily insert the scraper under the closing part of the window, it is probably not watertight!