In Gallura there are still many historic buildings made according to ancient local building techniques. These include the stazzi galluresi, rural stone buildings that are an important part of the area’s architectural tradition. These buildings, often built entirely of local granite, possess a unique charm, but frequently present problems related to rising damp.

Understanding how these dwellings were built is essential to intervene properly without compromising the balance of the building.

How the old granite houses in Gallura were built.

Ancient Gallura houses were built using local granite blocks bound with traditional mortars. Unlike modern construction, reinforced concrete was not used, but a mixture composed mainly of:

• Granular soil of different grain size;

• clay materials;

• hydrated lime.

This construction technique allowed buildings to “breathe” naturally, promoting the exchange of moisture with the external environment.

Foundations were also generally made of rubble stone, without the use of concrete slabs or beams. This very feature makes many of these structures today particularly susceptible to rising damp.

Why rising damp appears

One of the most common problems in older homes in Gallura is the presence of moisture rising from masonry and floors.

There can be several causes.

Floors made directly on the ground

Very often the original floor was laid directly on top of a subgrade of granular material, commonly called “sabbione,” without any impermeable barrier.

In practice, the typical stratigraphy consisted of:

• natural terrain;

• Mixed grain size;

• floor or tile.

Moisture in the soil then tends to evaporate and rise directly to the floor surface and then to the masonry.

Difference in elevation between indoor and outdoor

Another very common situation involves the external ground level.

In many ancient dwellings, the exterior floor is at the same level as the interior floor, or even higher. When it rains, water tends to accumulate near the masonry, slowly penetrating the stone and traditional mortars.

Over time this phenomenon causes:

• Detachment of plasters;

• molds;

• Salt efflorescence;

• Degradation of masonry;

• bad odors;

• Unhealthy environments.

The mistakes to avoid

One of the most common mistakes is to intervene with modern materials that are not compatible with historic masonry.

For example:

• Cementitious plasters;

• Waterproof plastic paints;

• nonbreathable resins.

These materials prevent masonry from transpiring, trapping moisture inside the wall and worsening the problem over time.

Old granite houses, on the other hand, must retain their natural ability to evaporate moisture.

How to solve the problem correctly

Each building needs a specific analysis, but there are some interventions that are very effective in most cases.

1. Removal of old, degraded plaster.

The first step is generally to descale and remove the old, deteriorated plaster to a height of about 1.50 meters.

At this stage it is important to eliminate:

• Cementitious plasters;

• Surface salts;

• Inconsistent or detached parts.

2. Use of breathable plasters

A new macroporous, breathable natural lime-based plaster is then made.

These plasters allow:

• The escape of water vapor;

• The reduction of salts;

• Better regulation of indoor humidity.

The final paint should also be breathable, preferably lime or silicate-based.

3. External drainage

One of the most important interventions consists of outdoor water management.

Whenever possible, it is advisable to make perimeter drains to divert rainwater away from the foundation of the house.

Proper drainage may include:

• Excavations around the perimeter;

• draining gravel;

• microperforated piping;

• filter geotextiles;

• Correct slopes of the terrain.

The goal is to prevent water from pooling near masonry.

4. Construction of a ventilated crawl space

In the most critical situations, it is often necessary to intervene on interior floors as well.

Generally, this is done by digging the inner subgrade to a depth of about 40 to 50 centimeters.

Next, a ventilated crawl space is made, which creates an air chamber under the floor capable of drastically reducing the presence of moisture.

The crawl space can be made:

• With large-sized stones according to traditional techniques;

• or by means of modular plastic elements (igloos or ventilated domes) that allow ventilation of the substrate.

Through special vents, air circulates under the floor, removing moisture accumulated in the soil.

Preserving historic houses while respecting their original functioning

The old granite houses of Gallura should not be treated as modern buildings. They are living structures, built with natural materials and traditional techniques that require compatible and respectful interventions.

Using the wrong materials or completely waterproofing masonry can make the problem worse instead of solving it.

For this reason, it is essential to rely on technicians and companies that really know how historic Gallura buildings behave.

Preserving a granite stazzo or house means not only eliminating moisture, but also keeping the architectural and cultural identity of Gallura intact.