The device of the exploited roof

Recommendation points

• Coating composition of operated roofs
• Straight-layered roof
• Inversion roof
• Pedestrian areas
• Automotive sites
• Vegetable areas
• Basic design requirements of operated roofs

Flat roofs of buildings are often used as outdoor sports, helipads, recreation areas, solariums, swimming pools, parking lots, etc. These types of roofs are called exploited. By the type of purpose of the structure on them or the form of use, the composition of the structure of the covering of the building is selected.

Coating composition of operated roofs

The composition of the coating for the operated roofs is selected depending on:

• operating conditions;
• type of supporting structure;
• loads and impacts on the coating;
• the climate of the construction area and the aggressiveness of the environment;
• the order of the arrangement of the layers of the coating structure (traditional, inversion);
• sanitary and fire safety requirements;
• performance properties of the materials used.

One of the main differences between the operated roofs is the additional load from the equipment used, the weight of people, vehicles and the increased loads from the coating materials. Therefore, all supporting structures of such a roof must be selected by calculation.

Straight-layered roof

The composition of the operated combined roofs of the traditional type involves laying the main waterproof carpet on the heat-insulating layer. A leveling, most often reinforced screed is arranged between them.

1 – floor slab; 2 – cement-sand screed; 3 – vapor barrier; 4 – insulation; 5 – waterproofing; 6 – reinforced screed; 7 – basic waterproofing; 8 – geotextile; 9 – tiles on plastic supports

The sequence of the roofing composition of direct placement:

1. Reinforced concrete floor slab.
2. Cement-sand screed (slope-forming).
3. Additional vapor barrier.
4. Insulation.
5. Reinforced concrete (cement-sand) screed.
6. Basic waterproofing.
7. Operated coating.

To protect the thermal insulation from moisture while the screed is being laid on it, a separating layer of waterproofing roll material is placed on the surface of the porous insulation. The elastic characteristics of the heat insulator are taken into account when calculating the thickness and quantity of the screed reinforcement.

Bitumen, bitumen-polymer, reinforced with a synthetic base, film elastomeric materials are used as the main and additional waterproof layer for operated roofs. The number of layers is accepted:

• for bitumen-polymer materials – 1-3 for the main layer and 1-2 for the additional one;
• for membranes – 1 layer.

EPDM membranes can be used for the construction of maintained roofs. They are made from thermoplastic rubber. They have high strength, resistance to sunlight, elastic, heat resistant. Their service life is up to 50 years..

Inversion roof

An inverted roof has a reverse layer arrangement. The main waterproofing layer is laid directly on the supporting coating. Further, thermal insulation is laid, along which the entire composition of the roof is already arranged, corresponding to the operational requirements of the structure.

1 – floor slab; 2 – slope-forming screed; 3 – waterproofing; 4 – thermal insulation; 5 – geotextile; 6 – drainage; 7 – geotextile; 8 – cement-sand screed; 9 – tiles; 10 – tin parapet

Inverted roof composition:

1. Floor supporting structure.
2. Lightweight concrete or cement-sand mortar screed forming a slope.
3. Ground base made of cement-sand mortar.
4. The main layer of water protection.
5. Thermal insulation.
6. Filter layer.
7. Operated coating.

For this type of roofs, it is allowed to use heaters made of materials with a low water absorption rate. These include polyurethane foam (PUR and PIR) thermal insulation, which is made on the basis of polyurethane foam and polyisocyanurate foam. This type of insulation also meets the requirements for the rigidity and strength of the insulator for inverted operated roofs..

The thermal conductivity index of polyurethane foam insulation is 0.022 W / m • K, which is less than that of extruded polystyrene foam (0.028 W / m • K) or mineral wool (0.038 W / m • K). This makes it possible, when using it, to reduce the thickness of the heat-insulating layer. In addition, PUR and PIR insulation has fire safety, bio-resistance and environmental friendliness, which is important for operated roofs..

The thickness of the heat insulator depends on the climate of the construction area and is assigned according to the heat engineering calculation. In terms of compressive strength, the insulation should have an indicator of more than 0.45 MPa.

Pedestrian areas

The “clothes” of the covering of terraces, observation, sports grounds, summer cafes are exposed to pedestrian loads and equipment. Waterproofing is performed for such roofs from at least 2 layers of mastic or roll-type polymer membranes. Its slope is 1.5–2% (1%). The slope of the ramps must be less than 10% (6%).

1 – floor slab; 2 – concrete screed; 3 – waterproofing; 4 – drainage material; 5 – insulation; 6 – geotextile; 7 – sand-cement mixture; 8 – paving slabs

Monolithic protective coating involves the use of concrete of class B25 (C20 / 25) grade M350 with frost resistance F150, reinforced with a mesh in the middle layer with 100×100 cells made of 5 mm S500 wire. Its layer thickness is allowed over 40 mm. Piece materials of “clothing” of the roof (slabs: sidewalk, concrete, ceramic, etc.) are placed on the preparation from a dry cement-sand mortar with a brand more than 100 frost resistance F150, sand, sand and gravel base. The sub-base must be more than 30 mm thick.

To protect moisture insulation from mechanical stress when installing drainage bedding, a separating layer of synthetic film with a thickness of more than 200 microns and geotextile is laid under it.

Automotive sites

Parking lots or areas that involve the passage of vehicles are subject to dynamic loads from the movement of vehicles and the weight of the vehicles themselves. For this type of roofs, waterproofing is performed with a slope of 1.5–5% (1–3%). Moreover, its composition assumes the use of rolled bitumen-polymer materials reinforced with a synthetic base, film membranes.

The top cover of the sites can be made from:

• monolithic asphalt concrete 40 mm thick;
• reinforced concrete slabs with a thickness of more than 80 mm with concrete class C20 / 25;
• paving (concrete) tiles with a thickness of more than 80 mm.

1 – floor slab; 2 – slope-forming screed; 3 – reinforced cement-sand screed; 4 – waterproofing; 5 – drainage layer; 6 – insulation; 7 – drainage layer; 8 – waterproofing; nine – reinforced cement-sand screed; 10 – asphalt concrete

The underlying layer for them is a monolithic reinforced concrete preparation (concrete of class C20 / 25), the thickness of which is taken to be more than 80 mm. As reinforcement, a mesh with 100×100 cells of 5 mm wire S500 or two composite mesh of a periodic profile with a diameter of more than 6 mm with cells 200×200 is laid in its middle layer.

A gravel backfill (fraction 3-15 mm) is made under the concrete screed, laid on the drainage cover made of geotextiles.

Vegetable areas

The slope of the operated roofs with grassy soil cover is also provided for 1.5-2% (1%). Waterproofing membranes or roll materials consisting of at least two layers are used as water protection. The protective coating is:

• soil substrate;
• a layer that creates a microclimate;
• filter layer;
• drainage layer;
• separating layer.

1 – concrete base; 2 – bitumen-polymer roofing membrane; 3 – insulation; 4 – separating layer (geotextile); 5 – drainage profile membrane; 6 – filtering layer (geotextile); 7 – fertile layer with plants

The thickness of the soil layer directly depends on the type of green space and is:

• 180 mm – for grass lawns;
• 240 mm – for flowering plants;
• 350 mm – for bushes;
• 750 mm – for trees.

A synthetic carpet is laid under the soil layer, soaked in a special solution to prevent root germination. It also stores moisture to create a microclimate..

The drainage layer is selected based on the horizontal water flow rate (at least 4.3 l / m / s) and the compressive strength indicator (more than 300 kN / m²). In addition, the biostability of the drainage material, its inertness to an alkaline environment and plant germination are taken into account..

Basic design requirements of operated roofs

When erecting roofs, it is very important to arrange thermal expansion joints with a minimum width of 5–10 mm. The size of the areas between the seams is:

• 6×6 m – for leveling cement-sand screeds;
• 4×4 m – for fine-grained asphalt concrete.

Expansion strips are laid along the temperature-shrinkage joints, the width of which is 15–20 cm. They are glued to both sides of the joints.

The waterproofing carpet can only be laid directly on the surface of the insulation, guided by the results of strength calculations, taking into account the ultimate strength and modulus of elasticity of the insulation. The adjoining of the roof to all protruding roof structures is protected from moisture by installing waterproofing on vertical surfaces by at least 25 cm.

The drainage system in the case of operated roofs is provided for internal. It is important to pay special attention to the junctions of the roof to the roof outlets, walls and parapet. They must be carried out taking into account all regulatory recommendations..

The number of funnels depends on the catchment area and is determined by calculation. For example, for roofs with greenery, the maximum distance between drainage funnels should be no more than 24 m.With an area of ​​up to 500 m² you can make one funnel with a minimum diameter of 10 cm.Their design is selected taking into account the type of roof.

The exploited roof solves the problems of large megacities with a shortage of areas. Roofs with greenery make it possible to enjoy all the benefits of nature without leaving the city, and sometimes even within your home.