How Poor Drainage Can Affect Your Home’s Footings

Poor drainage around a home is not always obvious. A yard may simply stay wet after rain, water may collect beside the slab, or one section of the property may take much longer to dry than the rest.

The concern is not usually that water is touching the concrete footing itself. The greater risk is the effect that repeated or concentrated moisture can have on the soil supporting the building.

Why soil moisture matters

A footing system relies on the ground beneath and around it providing reasonably consistent support.

When drainage is poor, water can remain around the building for extended periods. It may soften poorly compacted fill, contribute to erosion around trenches or create very different moisture conditions from one part of the house to another.

This is particularly important on reactive clay sites. Clay soils can expand as they become wetter and shrink as they dry. If moisture conditions vary significantly around the building, different areas of the supporting soil may move by different amounts.

That differential movement can eventually be reflected in the slab, footings and finishes above.

Common drainage problems around a home

Persistent moisture beside a house can have many causes, including:

• surface levels that fall towards the building
• low areas where water repeatedly ponds
• blocked or poorly positioned drainage pits
• leaking or disconnected stormwater pipes
• inadequate drainage around retaining walls
• rainwater tank overflow problems
• downpipes that are not correctly connected
• paved or landscaped areas that direct water towards the house
• insufficient provision for excess water during heavy rainfall

A drainage system needs to manage more than the water that enters a pit during ordinary rain. The way excess water travels across the site when the drainage system reaches capacity also matters.

Signs that drainage may be affecting the building

Possible warning signs include recurring ponding beside the house, constantly wet soil, moss or algae around the lower wall or slab edge, erosion, cracked paving or areas of the yard that remain saturated well after rainfall.

Where building movement is occurring, you may also notice stepped cracking in brickwork, cracks in render or plasterboard, cracked tiles, sticking doors or windows, gaps around cornices or skirtings, or floors that appear uneven.

These symptoms do not automatically mean drainage is the cause. Buildings can crack or move for many reasons. The important point is to investigate persistent moisture and building movement together rather than treating each symptom as an isolated cosmetic problem.

Fix the source before repairing the finishes

Repairing a crack, repainting a wall or replacing a damaged tile may improve the appearance, but it does not correct the moisture conditions that may have contributed to the problem.

The drainage source should be investigated first.

Depending on the property, this may involve checking surface falls, pits, stormwater pipes, downpipes, tank overflows, retaining wall drainage and the approved stormwater discharge arrangement.

Where substantial or progressive movement is present, a suitably qualified structural engineer may also be required to assess how the building has responded.

How ARK Houses can help

ARK Houses can assess practical drainage issues around residential properties and coordinate appropriate building, drainage and specialist input where required.

The objective is not simply to remove visible water. A well-considered solution should manage runoff, improve drainage around the building and reduce persistent moisture conditions that may affect the property over time.

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