Damp Walls

Damp Walls In Your Home

I posted on my blog, in November last year, about damp walls that arise as a result of not having gutters on your home to control the flow of rainwater off your roof.

On Saturday, I inspected a four-year-old property that had a one tile overhang on the roof. There were no gutters, but the house had paving surrounding it.

However, the external walls of the house were in a desperate state because of the three most destructive mistakes architects, developers, builders, and homeowners make!

As a result, I’m going to repeat some of the issues mentioned in my blog!

Damp walls caused by the lack of gutters

Gutters collect rainwater runoff from the roof through downpipes. These convey rainwater onto concrete rainwater channels away from the house in a controlled manner. In addition, they also protect the timber roof structure at the eaves of the house. Furthermore, gutters protect the house’s exterior walls, windows, and doors. They also protect the foundation from damp and potential damage.

The splashing against the walls was the most serious cause of the penetrating damp on the house walls. Moreover, the crazing cracking (spiderweb-like fine cracking) in the plasterwork was the main indicator of the penetrating damp caused by this splashing up of rainwater. Cracking was not observed higher up on the walls.

Even if your house has a reduced overhang at the eaves, gutters will still provide the required protection against heavy rain.

Insufficient roof overhang at the eaves

Roofs with no gutters and a two-tile overhang (600mm for a metal roof) or less will allow water to fall off the roof close to the walls, windows, doors, and the foundation.

14/03/201922/07/2025

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

Check the paint finish regularly on your boundary and garden walls. 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. Sprinkler 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 » home maintenance inspection

30/01/201927/08/2024

High Water Bills

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

Your high water bills 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 water 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 increasing your water bill. 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 several places to check if the water meter says you have water flow indicating a leak:

Leaking taps can increase your water bill

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

A big problem with increasing water bills is 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.

TPR Valve at the Geyser

The small valve with a flip-up handle at the top or side of the geyser is 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. If it is leaking it will increase your water bill! NEVER work on these valves yourself! Only a suitably trained and experienced plumber should!