Bay windows are a striking architectural feature. They add character to a home, but they can be prone to subsidence. This is because historically window bays were often constructed with shallower foundations because bays were considered lighter and therefore needed less support than the main house. These shallower foundations make window bays more susceptible subsidence in Ireland's temperate maritime climate.

Subsidence occurs when the ground sinks unexpectedly. This can be due to:

• Changes in the soil moisture levels because of the climate, which can cause the ground to shrink or swell. This can be a particular problem in the clay-rich soils found in areas like Dublin, Meath and Cork

• The roots of nearby mature trees, which can have a similar impact because these suck moisture from the ground, again causing it to shrink

• Heavy traffic local to a property can cause sub-surface vibrations which can result in subsidence

• Leaking drains which wash away soil particles, particularly in sandy soils, can destabilise foundations

• Historical land use such as mining or peatland drainage in rural areas can lead to ground settlement

One, or several, of these causes can lead to a window bay settling at a different rate to the main house. This differential settlement can lead to:

• Cracks and gaps appearing in walls, particularly between the bay and the main house, and

• Badly aligned windows, making them difficult to open and close.

If you notice signs of bay window subsidence the best course of action is to call in a specialist who can assess the problem and advise on the right subsidence solution for your home.

Mainmark provides swift, non-invasive solutions to correct bay window subsidence with minimal disruption. Our Teretek® resin injection technology and JOG computer-controlled grouting inject specially developed material into the ground beneath the bay's foundations. This will:

• Fill any voids;

• Improve the load-bearing capacity of the ground; and

• Lift and re-level the bay

After application, the bay will be raised and re-aligned as the ground underneath is strengthened and re-supported. Simple cosmetic repairs may be required.