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Introduction

Flat roofs were originally built in areas with low rainfall. For example, they can be found in the architecture of Egypt, Babylon and Mesopotamia. They appeared in the Central Europe with the discovery of the processing of asphalt strips at the end of the 18th century. In the modern era, the quality of insulation against atmospheric conditions increased so that flat roofs appeared on factory halls as well as highly architecturally appreciated buildings. They are a standard part of all types of buildings. The benefits of such roofs is that they save material, are less labour intensive, provide the option of variable roofing layouts and the potential use of roof areas. However, flat roofs also have disadvantages: the design of the composition of roof layers is complicated, as is the design of the thermal technical evaluation and all principles must be adhered to during implementation. Thermal imaging systems provide the perfect tool to evaluate the technical condition. The thermal imaging system located on the drone provides a fast and economical solution for surveying wide roofs on industrial sites.

Many places on flat roofs can be the source of defects (contact of the roof with the attic, penetration through the cover, inflows, etc.). Problems with leaks can occur in the area, for example, due to unprofessional installation, neglected maintenance or degradation of the surface due to insufficient protection of the surface layers against climatic influences or the end of the service life. In most cases, flat roofs are affected by excessive loading by wind, which causes dynamic shocks, permanent oscillating movement and lifting of unsecured parts. This phenomenon is also the source of the origination of leaks. Water collected on the damaged roof construction negatively affects the durability of roof clad (degradation of multi-layers, leaks).

Thermodiagnostics of flat roofs

A fast and simple way to resolve the problem of the inspecting various flat roofs exists. This method is a thermal imaging system (thermal camera), which due to the thermal difference between a dry place and a place with penetrating moisture, fully identifies discovers where moisture has penetrated. Depending on the construction of the roof, it is possible to see how large an area is affected by moisture, i.e. to localize and state the scope of the problem.

The physics behind the issue of thermal image inspection of problems related to the moisture is based on the fact that the dry part of the roof (not affected by moisture) is cooled and heated slower than the wet part of the roof insulation. Thermal image inspection using a thermal camera during or after sunset (where the roof has been heated throughout the whole time) identifies the moist areas because the dry parts of the roof cool slower than the wet places, which have a higher thermal capacity.

Why diagnostics from the air

Why? It is very easy!

Even when using a thermal camera, which is an excellent diagnostic tool, the question remains how fast and easily it can check the large area of a roof. The way round this problem is to use a pilotless aircraft on which the thermal camera is attached. Such an aircraft can fly above roofs and is not restricted by the number of ladders, elevations or unstable surfaces.

Why to use Workswell AIRvision

The company Workswell developed the Workswell AIRvision system, which combines two camera systems - a visible spectrum camera (for inspection of visible defects found by thermal camera) and a thermal camera for detecting the problems mentioned above. The servicing software enables to remotely switch camera regimes, to record radiometric videos or to make static images in both the visible and infra-red spectrum. The operator sees the objects under the drone in real time or can analyse records and identify damaged areas.

Moreover, Workswell AIRvision, unlike similar systems, enables to manually set the range of temperatures, e.g. in the interval of 15 °C to 25 °C. Even this range of temperatures can be changed during the flight. Without the need to land, the system actual situation can be set for the system and to easily achieve the required thermal sensitivity setting, which is required for the localization of minor moisture defects or the most precise localization of large defects. Traditional photo documentation is required to localise a defect, therefore, the Workswell AIRvision video camera is of sufficient quality to produce a traditional photo. Moreover, the system can be fitted with a GPS sensor for storing information about the position of the drone when creating a record.

The system can measure temperature at the central point, as well as in the local minimum and maximum. Minimum and maximum are localized using a blue (minimum) and red (maximum) cross. This function can also be used to navigate drones because the system automatically shows where the largest potential problem is located.

Produced records are fully radiometric, including videos. After termination of the flight, the records can be evaluated using the Workswell CorePlayer software to produce a measurement report on measurement with the exact localization of the problems. For this reason, a photo is available of all produced thermal images (thermogram).

Individual photos from the radiometric video can be taken and used as separate thermal images (thermograms) to analyse a problem.

More informations about drone thermal imaging system Workswell AIRvision including datasheet and drawings.