How to monitor cracks

Worried About Cracks In Your House? Having Sleepless Nights?

How to monitor cracks in your walls and floors!

Often, home buyers and homeowners are worried by cracks in the house and boundary walls, especially plastered walls!

The good news is that, generally, concrete, stone, brick, and masonry walls and concrete or screeded floors with cracks less than 1 mm wide (the thickness of a credit card) are common and usually do not warrant any corrective action. Most of these small, tight cracks are caused by normal shrinkage as the moisture in the walls and floors evaporates over time or by settlement of the structure, which usually occurs within the first few years after construction.

Be warned, however, that changes in and around the structure may also cause settlement many years later! Examples are planting a new garden or tree, or removing a garden or tree that is against or close to the house.

Crack Fillers

Note that all cracks should be sealed with paint, caulk (sealer), or mortar to prevent water from getting into the structure.

Moreover, if a horizontal, vertical, or diagonal masonry crack is filled with hard masonry patching compound, any substantial future movement is likely to show up as a new crack in the patched area or nearby. Therefore, always use a non-shrinking grout to prevent stressing yourself!

Continued movement

Cracks that continue to move are a reason for concern! Continued movement in cracks should be evaluated as correction may be necessary. Therefore, if you notice a crack has re-cracked or gotten larger, it should be monitored! However, first, make sure there is no shrinkage of the filler product. All 5 mm cracks or greater should be carefully monitored to ensure there is no continued movement.

02/09/201828/08/2024

Leaks at Window Sills

Moisture Intrusion at Window Sills

During many property inspections, I keep coming across moisture problems associated with water leaking into window sills and at windows.

Moisture absorbed into brickwork and plasterwork causes them to expand slightly. When the brickwork and plasterwork dry they contract slightly. The water absorbed by the bricks and plasterwork usually causes a slight vertical crack at the edges of the internal sills. The paint then starts to bubble along the vertical crack. This crack may continue around the length of the window sill before you notice it. What started as a small vertical crack then became a horizontal crack along the bottom of the window sill on the interior face of the wall.

The cracks are usually not significant unless allowed to continue unabated.

Rising Damp

Sometimes the moisture intrusion at sills is mistaken for rising damp! Water leaking in at the window sill may bypass the damp proof course (DPC) built in under the sill as a water-resistant barrier. The moisture may then appear as bubbling paint or crazing cracking of plasterwork, or both, below the window, extending down to floor level.

On external face-brick walls, this may appear as efflorescence (a white powder).

Internally, this may appear as bubbling paint above the skirting or discolouration of the skirting itself.

How do you prevent moisture intrusion into window sills?

12/07/201830/01/2025

Trees and Your Home

Tree Damage:

trees and shrubs
close to your home and clay soils can cause serious damage

Trees and large shrubs can cause major damage to your home, garden and boundary walls. This is especially true on the Witwatersrand where most areas and soils have some clay content. Without care and control, they may cost you a lot of money and no small amount of effort to fix.

Furthermore, shrubs should not be planted too close to the masonry walls either. The building regulations specify a minimum distance of 1,2 m for normal soils and 1,5 m if you have clayey soil.

Roots

Roots can also grow beneath your foundation footings, lift them or leach water from the ground beneath your house during dry spells and sink or settle the house unevenly.

They will cause the soil to dry out and in the case of clay soils, cause soil shrinkage.

Excessive watering or extended rain periods will cause the clay to swell. Subsequently, trees and large shrubs can cause movement in clay soils and damage your home and walls.

The movement amount depends on the percentage of clay content, the depth and extent of the root system and the efficiency of the roots to extract moisture from the soil.

When underground sewer and water pipes develop small leaks, roots quickly take advantage of those leaks. Before you realise it you have a blocked sewer line and pools of water and sewage in your yard.

What not to plant

All trees should be regarded as a potential source of damage. The following varieties are, however, particularly prone to causing damage:

03/07/201815/08/2025

Cracks and how to handle them

Don’t Panic when your house cracks!

crack defects in the foundation footings and walls — Changing moisture conditions under your house can cause defects in foundation footings and walls

Most homes develop defects such as cracks. Old and new homes can develop cracks in foundation footings and walls caused by climatic and physical factors.

However, it is worth getting to the bottom of what is causing the defect. A crack is the visible symptom of a possible problem or defect causing the crack.

What causes cracks?

New homes

In new homes, settlement may cause minor cracks. Normal foundation settlement occurs when the underlying soil compacts because of construction on previously undisturbed soil, changes in soil conditions and moisture. Typically small, hairline-sized cracks may indicate a minor settlement, expansion and contraction, or changes in a season or cycle.

Usually, these defects, though often unsightly, are not structurally significant.

Thermal movements between different materials

Different materials such as timber, bricks, steel, concrete etc. have different linear expansion coefficients. In other words, the differing materials contract and expand differently. This causes stresses in structures where they are combined and may cause cracking to form. The best way to combat these defects in plasterwork is to provide a joint between the different materials.

Older homes

In older homes, changes in climatic conditions can affect the structure. Houses move with the climate. Heat and moisture will make them expand, and cold and dryness will make them contract slightly. This movement is normal and in most cases will not cause cracking. Unusually hot or cold spells can increase the structural expansion or contraction which may cause cracks.

The rise or fall of the water table in very dry or wet conditions can also affect the house’s foundation footings.