The South Bay: seven ports, a high water table

The head of the Bay is the least publicised area and the most lived-in year-round. Gujan-Mestras and its seven oyster ports, Le Teich and its delta, Biganos and the Leyre valley: there are fewer showpiece villas here and more family houses, converted cabins and recent building.

It is also where Maison Aubier is based, at Le Teich. For a practical reason: from here, the whole Bay is within forty minutes, which is true from no other commune.

I. The water table, the dominant subject

The South Bay receives the inland waters: the Leyre, the Landes canal, the drainage channels of the Landes network, and a shallow water table often close to ground level.

That characteristic governs most of the local pathologies.

Rising damp. In older masonry with no damp-proof course, water rises through the walls to an equilibrium height, carrying salts that crystallise at the surface and blister the render. It is the most widespread fault in the area.

Crawl spaces and basements. Often permanently damp, with low-level vents blocked over time or by landscaping. An unventilated crawl space condemns the ground floor structure in the medium term.

Shallow foundations. On compressible and locally peaty soils, some older buildings show differential settlement. The resulting cracks are often stable, but they must be monitored — and monitoring cannot be improvised after the fact: it requires dated, repeated recording.

Two classic mistakes make things worse: applying an impermeable cement render at the wall base, which pushes water higher without removing it, and raising ground level against the façade during landscaping, which removes ventilation from the wall base. We set out the mechanisms in Salt air and humidity on a coastal villa.

II. The port buildings

Gujan-Mestras has seven oyster ports — Larros, La Barbotière, Gujan, La Hume, Meyran, Le Canal, La Passerelle — lined with timber cabins, some of which have been converted to housing or business use.

This stock has its own regime: timber construction in contact with damp ground, often close to water level, sometimes subject to an occupation permit where it stands on the maritime public domain, and generally governed by strict rules on appearance.

Maintenance points are close to those of the peninsula villages: cladding, timber bases, stainless fixings, low-pitch roofs. With one additional variable: ground moisture is higher here, which accelerates decay from the bottom up.

III. A remarkable environment, real constraints

The Leyre delta, the Teich bird reserve, the salt meadows and the former fish reservoirs form a protected natural ensemble of considerable value.

For adjoining properties this translates into planning and environmental constraints: wetlands, areas closed to development, restrictions on landscaping and fencing, and rules on works near watercourses.

Here too, checking with the planning department first is what avoids unpleasant surprises. It is free and takes one telephone call.

IV. What we inspect on the South Bay

Added to the common points:

• Humidity readings on lower levels, crawl spaces and basements at every winter visit.
• Inspection of low-level ventilation: clear vents, no soil or vegetation built up against façades.
• Dated photographic monitoring of existing cracks, with reference marks, to distinguish stable from progressing cracks.
• Inspection of timber bases on timber buildings and cabins.
• Inspection of drainage systems, particularly where treatment is not connected to mains drainage.
• Verification of sump pumps and perimeter drainage.

V. Where we are

Maison Aubier is based at 80 T rue des Poissonniers, Le Teich.

It is not the most flattering address on the Bay, and that is deliberate. The work requires being able to travel on a Sunday in January, within forty minutes, to any commune on the Bay. From the head of the Bay that is possible. From the point at Cap Ferret it is not.

Frequently asked questions

What are the most common faults on the South Bay?

Rising damp in older masonry, permanent humidity in poorly ventilated crawl spaces and basements, and differential settlement on compressible soils. Salt exposure, by contrast, is far lower than on the peninsula or the ocean front.

How should rising damp be treated in a house on the Bay?

By letting the wall base breathe rather than trying to seal it: clearing ground away from the façade, ventilating crawl spaces, using breathable lime renders, and installing perimeter drainage where justified. An impermeable cement render moves the problem upwards without solving it.

Can you live in an oyster cabin at Gujan-Mestras?

It depends on the land tenure and the applicable rules. Part of the port fabric stands on the maritime public domain, under a temporary occupation permit often tied to professional oyster farming. The exact position must be checked with a notary and the commune.

Why is Maison Aubier based at Le Teich?

For an operational reason: from the head of the Bay, every commune is within forty minutes, including out of season. That central position is what makes a genuine response capability possible, particularly in an emergency and in winter.

Should cracks in an older South Bay house be monitored?

Yes, through dated photographic records with reference marks, repeated over time. Most cracks from historic settlement have stabilised, but only repeated observation distinguishes a stable crack from a progressing one, and that distinction determines the technical response.