Special foundations

Underpinning — strengthening the foundations of an existing building

Underpinning specialists for cracked houses and settling structures.

Underpinning strengthens or deepens the foundations of an existing structure when they are no longer sufficient: growing cracks, differential settlement, clay soils weakened by drought. Sirianni Travaux works on houses, apartment buildings and older structures, for both private and professional clients.

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Giving a moving building sound bearings again

What is underpinning?

Underpinning covers the techniques used to strengthen, deepen or supplement the foundations of an existing building without demolishing it. It becomes necessary when cracks appear or worsen, when a slab settles, or when a vertical extension loads foundations that were never designed for it.

The most common causes are clay shrink-swell during drought episodes, poorly compacted fill, water ingress or insufficient bearing capacity. Depending on the diagnosis, underpinning is carried out with micropiles connected to the structure by transfer blocks, taking the supports down to stable bearing layers.

Why undertake underpinning?

Acting early stabilises the damage before it worsens — and preserves the value of the structure.

Stop cracks from progressing

Underpinning addresses the cause — the bearing — not just the symptoms visible on the façade.

Withstand repeated droughts

The clay soils of south-east France shrink summer after summer: anchoring deeper shelters the structure from these cycles.

Save the existing building without demolition

Work is carried out from the outside or the basement, with the house still occupied.

Prepare for a vertical extension

Strengthened foundations can safely take on new loads.

Special foundations expertise

Every underpinning scheme is designed from the ground, the structure and the geotechnical diagnosis.

A definitive solution

Anchored in stable layers, underpinning permanently resolves the bearing problem.

Our expertise

Know-how in special works

Sirianni Travaux carries out underpinning on damaged or weakened structures, in coordination with engineering firms and experts when the case requires it.

Our key skills

Underpinning with micropiles
Transfer blocks and ground beams
Strengthening of existing foundations
Work on occupied sites
Difficult-access sites

How a Sirianni Travaux project unfolds

Damage diagnosis

Analysis of the cracks, the structure and the geotechnical context.

Underpinning design

Choice of technique, sizing of the micropiles and connections.

Underpinning works

Drilling, grouting and progressive load transfer, on occupied sites where necessary.

Checks and monitoring

Verification of stabilisation and monitoring of the structure over time.

Frequently asked questions

When should underpinning be considered?

When cracks are progressing, ground is settling, or a survey questions the bearing capacity of the foundations — often after drought episodes on clay soils.

Do we have to move out during the works?

No, in the vast majority of cases: underpinning is carried out from the outside or the basement, with the house occupied.

Can underpinning be covered by insurance?

If the damage stems from a recognised natural disaster (drought) or falls under the ten-year warranty, cover is possible — we regularly work alongside insurance experts.

Which technique is used?

Most often drilled micropiles connected to the structure by transfer blocks; the choice and sizing follow from the geotechnical diagnosis.

How long do the works take?

From a few days to a few weeks depending on scale: phasing is designed to maintain the stability of the structure at every stage.

Is the result durable?

Yes: the loads then rest on stable deep layers, insensitive to surface moisture variations.

Let’s talk about your project or structural issue

Describe the situation — cracks, settlement, a new build — and we will come back to you once we have analysed the structure and its surroundings.

Phone06 59 90 51 91 Emailcontact@sirianni-travaux.fr

Address113 Allée des Cigales, 06700 Saint-Laurent-du-Var