Waterproofing of Earth-Sheltered Houses

Solutions & Applications · Waterproofing of Underground and Earth-sheltered Structures

Earth-sheltered houses — residential properties, hotels, and facilities situated below ground level — are a growing trend in Greek architecture, thanks to the sloping topography of many areas, the relevant legislation and lower energy requirements. However, they share one common feature: when the waterproofing fails, repairs are extremely costly and time-consuming, as the problem lies beneath the soil, a concrete slab or the floor. The system must be installed correctly from the outset.

What Constitutes an Earth-Sheltered House

In accordance with Law 4067/2012 (Government Gazette A-79/9 April 2012), An earth-sheltered house is a building or part of a building constructed below ground level, with the ground fully restored to its original form, and having only one visible façade. Its primary use may be residential, hospitality or as a workspace.

• Integration into the landscape: the structure follows the natural slope of the ground rather than disrupting it.
• Bioclimatic performance: the thermal inertia of the ground reduces energy requirements for heating and cooling.
• Protection: physical shielding against extreme weather conditions.
• Favourable town-planning regulations in certain cases, depending on the use and location.

The 3 Key Factors for Success

At ARGYNET, before we recommend materials, we always examine the same three factors that determine whether an earth-sheltered house's basement waterproofing system will last for decades or require repair within the first few years.

1. A composite system, not a single material: the waterproofing must ensure functionality even in the event of unforeseen localised damage — a fully bonded membrane, not a single line of defence.
2. Proven drainage capacity: depending on the surface load and the depth of the structure. A simple, unfiltered dimpled drainage membrane is not sufficient for an earth-sheltered house of primary use — a composite sheet with a filter and documented compressive strength for the load it will bear is required.
3. Radon barrier: radon is a colourless, odourless gas resulting from the natural decay of radium in the subsoil and is associated with respiratory diseases. In an earth-sheltered house used for primary purposes, the waterproofing layer must also act as a radon barrier — such as the ESHAFIN bituminous membrane in the version with internal aluminium reinforcement.

Membrane or Liquid-Applied Coating?

The choice between a membrane and a liquid-applied coating is not a question of cost but of long-term reliability:

Waterproofing Membranes	Liquid-applied Coating Materials
Consistent, industrially manufactured waterproofing thickness	Uneven thickness — depends on the installer
They incorporate reinforcement that increases mechanical strength	The reinforcement is installed separately — risk of incomplete impregnation
Long-term waterproofing, with no particular weather-related restrictions on application	Short-term, with strict temperature/humidity restrictions
Speed of installation, specialist contractor crews	Slow curing; specific curing times are required

Bituminous or Plastic Membrane?

Bituminous Membranes	Plastic Membranes
Manufactured thickness, from 2.5 mm per layer	Thinner sheet, usually up to 1.5 mm
Full adhesion to the substrate — any failure remains localised	Adhesion mainly at the seams — increased risk of leakage spreading
A large number of trained installation contractor crews in Greece	A limited number of specialist contractor crews
A variety of application methods (cold-applied, self-adhesive, hot-applied)	Limited methods, specialised equipment

Composite Drainage Sheet or Traditional Gravel?

Aggregates (Gravel)	Composite Drainage Sheets
Variable drainage capacity (natural product)	Consistent, predictable performance over time (manufactured)
Heavy-duty material, minimum thickness 100 mm, additional space	Lightweight sheet 6–25 mm, minimum dead load
Requires separate geotextile for the top and bottom	Composite product — filters already bonded to the core
Risk of damage to the waterproofing layer during installation	Protects the waterproofing layer

The criterion for selecting the sheet is its compressive strength in relation to the load it will bear. On the roof of the earth-sheltered house, beneath backfill and planting, a composite sheet with an HIPS core, such as Nophadrain ND 4+1h, provides 600 kPa. On vertical walls, where the load consists of lateral soil pressure, HDPE membranes with a pre-bonded filter are sufficient — DANODREN H15 PLUS with 180 kN/m² or MAXISTUD GEO with 150 kPa.

Standard Layering

1. Adhesion primer for concrete, for full bonding of the membrane.
2. Sealing of construction joints with a water-swelling bentonite cord prior to concreting the wall — it cannot be inserted afterwards.
3. Main bituminous membrane, fully bonded or self-adhesive depending on the pitch and geometry; where a radon barrier is required, available in a version with aluminium reinforcement.
4. Mechanical protection of the waterproofing prior to backfilling or concreting a slab on ground.
5. Composite drainage sheet with filter: for walls, HDPE with geotextile; for green roofs, a HIPS core with high compressive strength.
6. Drainage pipe with geotextile at the base, for the collection and discharge of water.
7. Backfilling with full restoration of the natural ground.

Waterproofing & Joints

Protection & Drainage

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