Flat roof waterproofing made of bitumen has proven itself for many decades and has been continuously further developed. Flat roofs are exposed to extreme temperature fluctuations (up to 100 °C over the course of the year), as are various types of moisture (building moisture, rainwater, temporarily standing water, moisture used by use) and mechanical stresses from the subsoil or from above, e.g. due to walking/driving, greening or hailstorm.

Image: Waterproofing of unused roof surfaces - bauwion

Image: Waterproofing of used roof surfaces - bauwion

Image: Waterproofing of balconies, loggias and pergolas - bauwion

Image: Waterproofing of trafficable areas - bauwion

Image: Waterproofing of rooftops covered with earth - bauwion

More about flat roof waterproofing made of bitumen/polymer bitumen membranes

Every

design should be based on the current edition of the standard applicable to the respective area of application, in conjunction with the current edition of the Flat Roof Directive, which contains specifications for many individual planning cases and is considered to be the generally accepted state of the art for the execution of a flat roof.

Notes on

planning the system: The compatibility and compatibility of the various component layers with each other must be checked. However, most manufacturers also offer tested systems for entire roof structures for the different requirements, so that there is certainty of layer compatibility for their planning.

Construction: In order to find the appropriate waterproofing structure and the suitable products for the respective project, an analysis of the framework conditions is first necessary, taking into account the applicable regulations. Examples: What use is planned for the roof surfaces? What is the substructure? Which application class is applicable? What roof pitch is planned? Is root penetration protection necessary? Which connection details and roof structures must be taken into account?

Connection and end heights according to DIN 18531-1 No. 6.7: In principle, horizontal waterproofing must be at least 15 cm high at each point on rising components, starting from the surface of the top layer, e.g. the waterproofing, the gravel fill or the slab covering. At the parapet, the waterproofing should always be carried to the outer edge of the façade. The waterproofing must be at least 10 cm above the surface of the flat roof at the parapet. The edge covers required for this should have a slope towards the waterproofing side.

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Extended warranty period: Some manufacturers offer a significantly extended warranty period for special roof waterproofing systems under certain conditions, e.g. 20 years. In addition to the prescribed use of components from a firmly defined roof system, comprehensive quality assurance is required, e.g. through the use of specially trained installers and TÜV monitoring of both production in the factory and installation on site.

Weather conditions: When applying seals, component surfaces must always be frost-free, and when processing liquid masses, both the component surface and the ambient temperature must be at least 5°C. Depending on the processing, it may also be necessary for the substrate to be absolutely dry, e.g. in the case of cold self-adhesive membranes or in the casting and rolling process, so that waterproofing work is dependent on the weather to varying degrees depending on the type of processing chosen.

Substrate: The substrate must be smooth, free of cracks and harmful contaminants. A separation layer/layer may be necessary to meet fire protection requirements (hard roofing) if a chemical incompatibility with the substrate is to be expected or if there is a risk of damage to the waterproofing due to unevenness/roughness of the substrate. Further requirements for the substrate are regulated, for example, in DIN 18531-1 Section 7.

Protective measures: Protective measures serve to temporarily protect the waterproofing during further construction measures and must be adapted to the type and duration of the construction measures until the final protective layer is produced. Chemical substances that can damage the waterproofing must also be taken into account, e.g. lubricants, solvents or formwork oil. No loads may be placed on unprotected waterproofing and the surfaces must only be entered with suitable footwear and if absolutely necessary.

Inspection and maintenance: Roof waterproofing requires regular inspection and maintenance in order to achieve a long service life. Further details are regulated in DIN 18531-4, for example.

It is advisable to conclude a maintenance contract with a suitable specialist company. The written documentation of the inspections should also record the need for any necessary maintenance, servicing or repair work.

Documentation: In order to enable proper maintenance, documentation of the materials used in the roof structure should be made and these should be handed over to the client after completion of the work, together with reserve samples.

Standards and Literature

DIN 18195 Waterproofing of Structures - Terms

DIN 18234 Structural Fire Protection of Large Roofs - Fire Exposure from Below:

Part 1: Definitions, Requirements and Tests; Closed roof surfaces
Part 2: List of roofs that meet the requirements of DIN 18234-1; Closed roof surfaces
Part 3: Definitions, requirements and tests, penetrations, connections and closures of roof surfaces
Part 4: List of penetrations, connections and closures of roof surfaces that meet the requirements of DIN 18234-3

DIN 18531 Waterproofing of roofs as well as balconies, loggias and pergolas:

Part 1: Unused and used roofs - Requirements, planning and execution principles
Part 2: Unused and used roofs - Materials
Part 3: Unused and used roofs - Selection, design and details
Part 4: Unused and used roofs - Maintenance
Part 5: Balconies, loggias and pergolas

DIN 18532 Waterproofing of drivable concrete traffic areas:

Part 1: Requirements, planning and implementation principles
Part 2: Waterproofing with a layer of polymer bitumen welding membrane and a layer of mastic asphalt
Part 3: Waterproofing with two layers of polymer bitumen membranes
Part 5: Waterproofing with a layer of polymer bitumen membrane and a layer of plastic or elastomer membrane

DIN 18533 Waterproofing of Components in Contact with the Ground:

Part 1: Requirements, Planning and Execution Principles
Part 2: Waterproofing with Membrane Waterproofing Materials

DIN 31051 Basics of Maintenance

DIN 18338 VOB Procurement and Contract Regulations for Construction Services - Part C: General Technical Contract Conditions for Construction Services (ATV) - Roofing and Roof Waterproofing

Work Flat Roof Directive Technical Rules for Waterproofing, Regulations of the German Roofing Trade

Source: bauwion