Before / after: transforming a house through underpinning

Underpinning is one of the most technical operations in structural building work: it consolidates or rebuilds the foundations of an existing building without demolishing it. It is an operation that often causes concern, when in most cases it is precisely the solution that avoids having to rebuild at all.

How to recognise a house needs it

Several signs should raise a flag: cracks running diagonally across a wall, a visible settling of one corner of the house, a door or window that increasingly sticks, or ground that dips slightly along a facade. On the Var coast, these issues are often linked to clay soil, a natural slope in the ground, or a retaining wall that has become insufficient over time.

A case we see often on our sites

A typical situation: a 1970s villa, built on a sloping plot without a thorough soil survey at the time. Over the decades, one corner of the house settles gradually, causing cracks visible both inside and outside, and a patio door that no longer closes properly. The survey reveals loose ground under that specific corner, unable to properly bear the existing foundation.

The method: from soil survey to consolidation

Underpinning always starts with a soil survey, to identify the depth of stable, load-bearing ground. Depending on the results, the technique chosen may be micropiles, drilled down to stable ground and connected to the existing foundation with ground beams, or reinforced concrete pad underpinning, carried out in successive sections so the whole building is never destabilised at once.

What actually changes once the work is finished

• Existing cracks are treated and do not come back, because the cause of the movement has been removed.
• Doors and windows go back to working normally.
• The structure regains a stable footing, which secures the building for decades to come.
• The property's value is preserved, where an untreated structural issue would eventually have driven it down sharply.

A more accessible operation than it sounds

Contrary to popular belief, underpinning does not necessarily mean months of work or a runaway budget. Its duration and cost depend directly on the extent of the issue and the area affected, which makes early diagnosis all the more useful, before the cracks get worse.

A cracking house is not necessarily a lost cause. Properly diagnosed and treated at the source, underpinning gives the structure back its full strength, often for a fraction of what a rebuild would cost.