ETICS systems that are correctly specified and installed have a proven service life of over 30 years. When defects arise — such as cracking, water ingress, delamination or deterioration of the finish — the cause is almost always to be found in the inappropriate specification of components, the omission of procedures or insufficient preparation of the substrate. This article identifies the most common defects, their causes and the procedures that prevent them.

Cracking of the base coat and top coat

Cracking is the most visible and most common defect in ETICS systems. It can manifest as linear cracks along the joints between panels, diagonal cracks at the corners of window and door openings, or widespread micro-cracking on the surface of the finish.

Cracks in the joints between slabs

These occur when the joints between insulation boards are not properly filled or when the boards have not been laid on battens. The correct procedure requires vertical joints to be staggered by at least 25 cm and gaps to be filled with insulating material or foam, never with mortar (which would create thermal bridges).

Diagonal cracks at the corners of spans

They are one of the most common types of damage. They result from the concentration of stresses at the corners of windows and doors. Prevention requires diagonal reinforcement with strips of fibreglass mesh measuring approximately 200×300 mm, applied to the substrate at a 45° angle before the reinforced mesh is laid. Failure to provide this reinforcement is the direct cause of diagonal cracking.

In the openings, the insulation boards must be cut into an L-shape to fit around the corners. The joints between boards must never coincide with the corners of the openings.

Linear cracks caused by the absence of expansion joints

On large façades (exceeding 8 linear metres), the absence of expansion joint profiles results in linear cracks running through the cladding. Any existing expansion joints on the façade must be left intact and must never be covered by the insulation boards. The expansion joint profile absorbs structural and thermal movements without transferring stresses to the cladding.

Generalised micro-cracking

This is often caused by fibreglass mesh that is too thin, has not been properly treated against alkali, or has been positioned incorrectly within the mortar layer. The mesh must be positioned in the middle of the total thickness of the base layer (approximately 4 mm), perfectly taut and thoroughly saturated. The overlap between strips must be at least 10 cm. The mesh must comply with the criteria of EAD 040083-00-0404: tensile strength after ageing in an alkaline solution of not less than 20 N/mm and not less than 50% of the strength when new.

Water seepage

Water ingress in ETICS systems predominantly originates at specific points, rather than along the continuous surfaces of the façade. When correctly installed, the system is not prone to cracking, and the outer layers ensure impermeability to rainwater.

Infiltration from below

This occurs when the starter profile does not adequately protect the base of the insulation against rising damp and splashes. The starter profile must be installed at a minimum height of 15 cm above the finished floor level. The choice between aluminium and PVC depends on the level of exposure: aluminium for greater mechanical strength in exposed areas, PVC for sheltered areas.

Infiltration through gaps

This is caused by the absence or incorrect installation of drip mouldings on the lintels of window and door openings. Without drip mouldings, rainwater runs down the façade and penetrates the interface between the cladding system and the window and door frames. The drip channel integrated into the profile interrupts the water’s path and diverts it away from the wall.

Blending into the edges with contour elements

Where the system meets rigid elements (window frames, window sills, parapets, flashings), a joint of at least 5 mm must be provided, filled with an elastic sealant compatible with the material of the insulation board. Sealing is carried out once the final finish has dried, by applying a bead of sealant. Failure to carry out this sealing is a frequent cause of water ingress at the points of contact between the system and adjacent elements.

Insulation delamination

Partial or total detachment of the insulation boards is caused by a failure in the adhesive bonding, the mechanical fastening, or both.

Bonding failure

The adhesion of the adhesive mortar depends on the preparation of the substrate. Surfaces must be mechanically sound, clean and free from dust, dirt, grease or formwork release agent. Surface irregularities exceeding 1 cm (measured with a 2 m straightedge) must be corrected with suitable plaster before bonding.

On new concrete substrates, at least one month must have elapsed since the concrete was laid before the system is applied. On plastered substrates, the plaster must be firmly bonded and have a suitable surface texture. Any plaster that is flaking must be removed and repaired.

On walls subject to rising damp caused by capillary action, the ETICS system must not be applied. Bonding the insulation board increases the moisture load on the wall due to reduced evaporation.

Insufficient mechanical fastening

Mechanical fixing complements the adhesive bonding. The wall plugs must comply with the requirements of ETAG 014, with 6 to 8 units per m². The length of the wall plug must be at least 3 cm greater than the thickness of the insulation board. The wall plugs must be recessed into the panel and checked individually. Any that are damaged or loose must be removed and replaced in a new hole.

The drilling must be appropriate for the substrate: the percussion method for concrete and solid brick, and the standard method for perforated brick. The layout depends on the insulation: a T-pattern for EPS, ICB and XPS, and a W-pattern for mineral wool.

Premature deterioration of the finish

Colour change and degradation caused by UV radiation

The use of dark colours in the final finish accelerates degradation caused by solar radiation. Surface temperatures of the system can exceed 50°C, compromising the stability of the coating. The solar radiation absorption coefficient (α) must be less than 0.7. Dark colours exceeding this value are not recommended.

Stains and streaks

They are often caused by the absence of drip edges in the openings or by the inappropriate design of the drip moulding. Water that continuously runs down the same area of the façade creates stains due to the build-up of dirt and micro-organisms. The correct installation of drip edge profiles with a functional drip moulding prevents this problem.

Uneven texture

The finished surface must be level, with no irregularities exceeding 1 mm. This levelness depends on the entire construction process: from the even bonding of the insulation boards to the uniform application of the final finish. The use of textured finishing materials helps to minimise the perception of minor imperfections. Fine or smooth textures make surface irregularities more apparent.

Conditions for use that help prevent diseases

The ETICS system must be installed in accordance with specific weather conditions. The ambient temperature must not exceed 30°C or fall below 5°C. The system must not be installed in strong winds, rain or in direct sunlight.

The work must be carried out by specialist fitters with the appropriate training. The success of the installation also depends on the solution having been specified in advance and the construction details having been worked out by specialist technicians.

Summary: component and pathology that prevents

The starter profile prevents water ingress at the base. The corner profile and diagonal reinforcement prevent cracking at the corners of the spans. The drip edge profile prevents stains and water ingress on lintels. The expansion joint profile prevents linear cracking on large façades. Fibreglass mesh of the appropriate weight and with the correct treatment prevents widespread micro-cracking. Correctly specified wall plugs prevent the insulation from becoming detached. Elastic sealant at the edges prevents water ingress at points of contact with surrounding elements.

2rf range

2rf supplies all the components required for preventing defects in ETICS systems: starter, corner, drip edge and expansion joint profiles; fibreglass mesh certified to EAD 040083-00-0404; anchors compliant with ETAG 014; and waterproofing and sealing accessories. The range is available from the 2rfpro.pt online shop.

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