Flat roof structures and balconies are the elements of buildings that are most exposed to external weather conditions. Depending on the needs, flat roofs can be trafficable, non-trafficable or green roof systems. The materials for installation and finishing of these systems are contingent upon the type of flat roof.

1. Waterproofing of trafficable roof terraces

We will focus our attention on trafficable roof terraces and balconies and the application of the waterproofing system on those surfaces as a precondition for durability of the building. In the process of design and installation of a waterproofing system on trafficable roof terraces and balconies or when repairing an old waterproofing system, we should factor in the impacts that affect the terraces and balconies, the slope of the substrate and the type of substrate (monolithic or blocks) on top of which the waterproofing system will be applied.

We will single out some case studies of waterproofing systems on trafficable roof terraces and balconies that turned out to be success stories and meet the requirements of the waterproofing function (DETAIL 1 and DETAIL 2) using the products manufactured by ADING and TPH (Germany).

The reinforced concrete finish, which is a substrate of the entire roof system, should be waterproof and with a closed structure. The concrete must be properly placed and cured and without any occurrence of cracks. Therefore, in the process of concrete production, we recommend the concurrent use of two types of admixtures: SUPERFLUID – high-range water-reducing superplasticiser and HIDROFOB 21 – concrete and mortar admixture for prevention of capillary water absorption and formation of water-repellent surfaces.

On top of the concrete surface which should be at least 28 days old we should install a waterproofing system by using HIDROMAL – ready-mix compound for the installation of a cement-based rigid waterproofing system prepared by using a specially selected cement, high-quality fillers and powdery admixtures. It is applied as a waterproofing system on buildings exposed to positive and negative hydrostatic pressure. It is applied on a concrete or cement-based substrate. The material is prepared by adding clean water and mixing them until a completely uniform mixture is obtained. Then, it is applied by using a brush or a steel trowel. 

We recommend that the installed waterproofing system made with HIDROMAL be protected with a foil for balancing the vapour pressure – vapour barrier, thermal insulation and PE foil.
When laying a reinforced-concrete screed to form a slope with minimum thickness of 8 cm, it is necessary to add HIDROFOB 21 waterproofing admixture to the concrete mixture in doses of 0.8% of the cement mass.

When installing the siphonic drainage system, it is necessary that the siphon be fixed and the outlet be sealed. For this purpose, we will use EKSMAL – one-component, self-levelling, ready-mix cement mortar used for grouting of sections (for anchor grouting, grouting of load-bearing element foundations, crane beams, machine foundations, grouting of vertical and horizontal openings in concrete elements and structures). It provides high early and final compressive strength. In addition, joints should be treated with the durable elastic sealant FIX-O-FLEX – one-component, paste-like sealing compound which in contact with water is transformed into an elastic material.

The reinforced-concrete screed installed to form a slope should be protected with a waterproofing system made of HIDROMAL FLEKS 1 – two-component, elastic, cement-based waterproofing system prepared by using specially selected cement, high-quality fillers, admixtures and polymers. It is applied as a waterproofing system on buildings exposed to positive and negative hydrostatic pressure. The substrate can be made of concrete, cement mortar or plasterboard sheets. According to the method of preparation, the powdery A component should be gradually added into the liquid B component and they should be continuously mixed until a completely uniform mixture is obtained. Then, the mixture is applied in two or three layers by using a brush.

After installing the waterproofing system made of HIDROMAL FLEKS 1, we should begin with the process of fixing ceramic tiles by using HIDROKOL SP – one-component, watertight, polymer-modified, cement-based tile adhesive. The adhesive is intended for fixing of floor and wall tiles exposed to external weather conditions, moisture and water. It should be applied on top of a sound substrate made of concrete, cement or compo mortar. The adhesive is prepared by adding water and the mixture is applied along the surface where the tiles are to be fixed by using a trowel or a scraper. To seal the joints, we use FUGOFIL – cement-based waterproof pointing sealant used for sealing joints measuring up to 5 mm in width in horizontal and vertical surfaces covered with ceramic, marble, glass, stone or concrete tiles. It is used for pointing joints in sanitary blocks, kitchens, balconies, pools, staircases, halls, warehouses, manufacturing plants, etc. The mixture is prepared by adding water and it is applied on the surface by using a rubber trowel in such a way that the joints are properly filled. 

DETAIL 1: Waterproofing system of a trafficable roof terrace

	DESCRIPTION
1	ceramic tiles
2	tile adhesive HIDROKOL SP (C2ES1)
3	waterproofing with HIDROMAL FLEKS 1 in three layers
4	grouting with EKSMAL
5	reinforced-concrete screed to form a slope d=8cm with a waterproofing admixture HIDROFOB 21 (0.8%)
6	PE foil
7	thermal insulation
8	vapour barrier
9	waterproofing system with HIDROMAL – two layers
10	reinforced-concrete block with waterproofing admixtures SUPERFLUID and HIDROFOB 21
11	cement mortar
12	HIDROGLET V
13	ADINGKOLOR

In order to provide additional protection to the joints between horizontal and vertical surfaces, we suggest to apply PROOFMATE FD FOIL – elastic waterproofing foil based on EPDM (ethylene propylene diene monomer) by fixing it with the durable elastic sealant FIX-O-FLEX and sealing the joints between the vertical and horizontal ceramic tiles (Detail 1a).

The temperature differences (ranging from -20˚C to +40˚C) specific of our climate lead to shrinkage and expansion of the structure. In order to prevent the occurrence of cracks, it is recommended to make construction joints with reinforced-concrete screed on areas of 9-12 m², to seal them with the durable elastic sealant FIX-O-FLEX, to cover the construction joint with PROOFMATE FD FOIL applied on top of FIX-O-FLEX. In addition, it is recommended that the joint of the ceramic tiles should overlap with the construction joint of the screed and it should be filled with the durable elastic sealant FIX-O-FLEX (Detail 1b).

2. Waterproofing of a balcony

Apart from the abovementioned recommendations for use of the materials for installation of a waterproofing system, DETAIL 2 shows a cross-section of a structure of a balcony and provides a solution for the installation of a waterproofing system.

DETAIL 2: Waterproofing of a balcony

In addition, DETAIL 2a and 2b show some solutions for the treatment of joints between the horizontal and vertical surface and the treatment of the joints between the structure and the doorsill by using ADINGAKRIL - one-component, acrylate-based, waterproof, elastic sealant.

Radica Gjoneska, Bachelor of Architectural Engineering