How to repair cracks in terraces or outdoor surfaces

Why do cracks often appear on the terrace floor?

Cracks in the terrace floor can appear for a variety of reasons, some of the most common are:

1. Expansion and contraction: The terrace floor expands and contracts with changes in temperature and humidity, which can lead to cracks and fissures in the surface. If the deck is exposed to large temperature changes, such as in extreme climate zones, cracks are more likely to appear in the floor.
2. Lack of levelling: If the terrace floor has not been correctly levelled, cracks may appear due to water accumulation in uneven areas. This can be particularly problematic in areas with rainy or humid climates.
3. Ground settlement or loading: if the terrace has been built on unstable or moving ground, such as in seismic zones, cracks may appear in the ground due to changes in the ground, also due to the loading of the building with elements of use by the property.

It is important to note that cracks in the terrace floor are not only an aesthetic problem, but can also be a safety problem, as they can cause trips or falls, and a health problem, as they can lead to water seepage.

It is therefore advisable to take measures to prevent their appearance, such as choosing suitable, quality materials, levelling the floor correctly and carrying out regular maintenance and repairs to avoid cracks and leakage problems on terraces.

Repairing cracks in the terrace: how should we do it?

Repairing cracks in the deck can be a simple task if the proper procedure is followed. But the repair will depend on the finish of the terrace, whether it has a ceramic finish, an acrylic finish, polyurethane, etc. In this sense, below we summarise the four steps to achieve this in an effective way:

Step 1:

Prepare the surface: Before starting to repair the cracks, it is important to prepare the terrace surface to ensure that it is clean and dry. To do this, any dirt, dust or debris should be removed using a broom, hoover or pressurised water hose.

Open and clean the cracks manually or with a grinder to a minimum of 2 cm if it is screed mortar and 1 cm more than the thickness of the tile in the case of cladding. Make sure that no pipe can be cut through.

Step 2:

Apply the sealant: Once the surface is clean and dry, it is necessary to apply a joint sealant on the underside. Molins has a sealant for the treatment of joints and cracks, BETOFLEX MS45, a highly durable and totally innocuous modified polymer sealant, which can be applied by spray gun. The application must leave at least 1 cm above for the application of the mortar or the thickness of the ceramic tile.

Step 3:

Allow to dry: After applying the sealant, it should be allowed to dry for at least 24 hours before continuing with the repair. During this time, it is important to prevent the deck from getting wet so that the sealant can dry properly.

Step 4:

Filling with grout: Once the sealant is dry, the crack or joint can be filled with mortar. This mortar can be PROPAM® REPAR TECHNO 20 or in the case of BORADA PLUS ceramic joints by Molins in the colour that best matches the existing one, it should be applied with a spatula to ensure that it is well levelled. After applying the mortar, it should be left to dry for at least 48 hours before walking on the terrace.

If there are already loose ceramic tiles, it is recommended to intervene with BETOTAPE SEAL elastic band glued and covered with PROPAM® IMPE FLEX waterproofing before re-bonding the existing tiles.

In the case of terraces with acrylic or polyurethane finishes, we can finish the repairs with BETOPAINT 91 FIBRES or PROPAM PUR, respectively.

It is important to note that if the cracks in the terrace are very large or occur frequently, it will be necessary to carry out a more thorough review of the terrace structure to identify possible foundation or structural problems that are causing the cracks. In these cases, it is advisable to seek the advice of a specialised professional.

Molins products for repairing cracks in terraces

BETOFLEX MS45:

New technology elastic polymer sealant adhesive putty based on high quality, single component, silane modified polymers, suitable for sealing and bonding of most substrates used in the construction industry, civil-residential works, shipyards, automotive, etc. Remains elastic after curing. Excellent adhesion and chemical resistance.

BETOTAPE SEAL:

High-performance waterproof elastic band for sealing joints and meetings. It is a high performance sealing system for expansion joints, joints, half-joints, cracks or fissures, composed of a highly elastic and waterproof strip of thermoplastic elastomer (TPE) with a thermo-welded polypropylene geotextile over its entire surface and on both sides. Once fixed to the substrate, it allows the joint to move, both indoors and outdoors.

PROPAM® IMPE FLEX:

Hydraulic mortar that acts as a flexible waterproofing coating, it is formulated with cement, selected aggregates and special waterproofing resins. It is one of the products recommended for waterproofing terraces.

BORADA® PLUS:

It is a special mortar based on special cements, siliceous aggregates of selected granulometry, organic and inorganic additives and stable mineral pigments.

BORADA® UNIVERSAL:

Special mortar based on cement, aggregates of selected granulometry, resins, organic additives and stable mineral pigments.

BETOPAINT 91 FIBRES:

Single-component coating based on acrylic resins in aqueous dispersion, fibres and special fillers, which, once dry, forms a waterproof, continuous, flexible and elastic membrane for application on roofs and terraces.

PROPAM® PUR:

One-component pigmented liquid polyurethane membrane that forms a continuous waterproof, highly elastic, weather-resistant and weatherproof membrane with excellent adhesion when polymerised, for waterproofing and protecting surfaces.

BETOFIBER POLYESTER:

It is a solvent resistant polyester fibre geotextile, suitable for the reinforcement of singular points and problematic areas in the application of polymeric waterproofing membranes.

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