Ireland: a challenging landscape

The average annual rainfall in Ireland varies significantly by region, with eastern parts of the country receiving between 750-1000mm of rain per year and the west receiving around 1000-1250mm of rain per year, sometimes more. 

This is problematic in a country dominated by variable soils. Much of Ireland is covered in clay-rich soils and peat, which swells during periods of wet weather and shrinks during prolonged spells of warm, dry weather. Peat, which covers around a fifth of the country, is especially vulnerable to movement, sometimes shrinking by almost a metre a year. 

Additionally, the frequent rainfall can overwhelm drainage systems, which can lead to a water build-up around the foundations. This can weaken the soil, causing ground movement. 

Cracks and settlement can also be a result of poor backfill during construction. Crushed pyrite, a common iron sulphide, was used extensively in foundation backfill during the construction boom of the Celtic Tiger era (mid-1990s to late 2000s), particularly in the East of Ireland. However, when exposed to oxygen and moisture it oxidises to form thin, needle-like crystals that expand, lifting floor slabs and causing cracks to appear. Once this process starts, the damage gets worse over time.  

Homes affected by pyrite lose value as a result, because future buyers may fear the cost of remediation works. Works involve removing the entire contaminated infill, which is both highly disruptive and expensive.

Cosmetic vs structural cracks

Not all cracks are a sign of structural damage, however, thin or hairline cracks are commonplace and typically caused by natural building movement, temperature changes or minor shrinkage. This type of crack is especially common in houses over 10 years old or in properties that have recently been refurbished.  

Common signs of cosmetic cracking: 

• Less than 2mm wide 

• Horizontal or vertical in plaster 

• In one area, usually around windows and doors 

• No ongoing change in size or pattern 

Structural cracks are far more serious and it’s advisable to seek professional help if any structural cracks appear. 

Common signs of structural cracks: 

• Wider than 5mm 

• Diagonal or stepped cracks in brickwork 

• Sudden appearance of multiple cracks 

• Cracks worsening over time 

• Cracks accompanied by sloping floors or sticking doors 

• Bulging or bowing of walls  

• Cracks appearing near chimney breasts, foundations or the roof 

Why it’s important to seek professional advice early

Ignoring the signs of structural movement can lead to significant further damage and expensive repair costs. Homeowners can keep an eye out for any changes in cracks and movement by: 

• Keeping a photographic record of cracks 

• Monitoring crack width 

• Making notes of changes over the seasons 

An early inspection by a residential surveyor or structural engineer can identify the issues quickly and prevent further damage and expense. 

How to fix the problem 

Cosmetic or hairline cracks can be repaired easily with plaster repair, filler, or paint; structural cracks, however, demand more robust methods. 

Weak, unstable ground 

If the issue is caused by weak or unstable ground, specialist solutions such as ground strengthening or soil stabilisation may be required. Soil stabilisation enhances the properties of the soil, so that it effectively supports the weight of the property. This can be done using traditional techniques or by deploying techniques that use chemical binders, which compacts the soil without excavation, material removal and the import of aggregates. 

Subsidence 

If foundations need extra support because of subsidence issues, for example, underpinning may be recommended. Traditional underpinning methods may be taken to strengthen the base the property sits on and to re-level the structure. This method requires digging beneath the foundations and filling the holes with concrete. Although it’s an effective method, it can be disruptive and slow, typically taking weeks to complete.  

Modern approaches such as ground injection underpinning, often used by Mainmark Ireland, offer a faster and less disruptive alternative. This method involves injecting under the foundations to fill voids, strengthen the ground, and carefully re-level the property if necessary. 

Sunken or uneven floors 

Slab lifting techniques can raise floors that may have sunk or become uneven, back to level by filling voids beneath with specialist materials. This is another solution offered by Mainmark Ireland, which often allows homeowners to remain in their property during the works. A professional assessment will help ensure the most appropriate solution is chosen.  

Cracks and settlement may be a common reality in Irish homes, but that doesn’t mean they become a costly nightmare. Identifying the difference between cosmetic and structural damage, monitoring change and getting professional help early on avoids further problems developing and escalating costs. 

If you suspect ground movement on your property, speak to Mainmark Ireland today.