For the new construction of Hall 27 on the Berlin Exhibition Grounds, the client, planners and roofers played it safe: a sensor system shows the functionality of the waterproofing via app.
Messe Berlin GmbH is currently working on the construction of a new multifunctional hall. It is intended to provide space for congresses, meetings and conferences and at the same time serve as a flexible alternative option when the entire exhibition grounds are gradually being renovated within the next 15 years.
13,000 m2 flat roof
One of the most important challenges for the hall named „hub27“ is therefore also to ensure continuous operation. For this reason too, the trade fair is relying on modern structural monitoring for the approximately 13,000 m2 flat roof, which is intended to reduce the need for renovation and increase the building’s service life. The system used is cable and battery-free and promises particularly easy installation and control.
Visit on the construction site
Monday, 8 am in July 2018, the thermometer already shows 20 degrees. The summer of the century could certainly be better enjoyed at one of Berlin’s many bathing lakes, but for the roofing company Schwind from Saxony, the sky is high again on this day.
There are still three weeks to go until the topping-out ceremony for the new exhibition hall – Frank Lenser and his colleagues have to inspect the completed roof today. Normally a routine job for the experienced roofers, but today is a premiere.
The client and planning office decided to integrate sensors into the flat roof. These should make it possible to check the flat roof for moisture penetration at any time and so detect damage as early as possible. For example, even before acceptance – and this is precisely the inspection that the roofers are planning today.
Installation of the sensors
The small, green boards were installed by the Schwind company a few weeks ago at the same time as the mineral fiber insulation. Not every insulation board was equipped with a sensor; the tender stipulated the installation of one sensor per 4 m2. Depending on the condition and size of the roof, the Berlin-based manufacturer Hum-ID recommends three different sensor grids.
The custom-made installation plan for the roof of exhibition hall 27 also takes into account the special features of this flat roof: critical areas such as the low points were equipped with more sensors, less critical areas such as the ridges of the roof with fewer sensors.
Control by App
Two weeks after installation, nothing more can be seen of the wireless and battery-free sensors that are stuck in the insulation, because in the meantime the roof has been sealed with two layers of bitumen. It is an exciting moment: Roofer Frank Lenser switches on the reader and connects it to his smartphone. The sensors are controlled by the RFID radio standard. The green sensor in the roof structure is supplied with energy for a fraction of a second by the reader during the inspection. Enough to send its identification number and the wet condition to the reader. This information is displayed to Frank Lenser in real time on his cell phone in the control app.
For the experienced roofer it is the first time that he can check the tightness of a flat roof with the help of sensors. However, the long-time foreman is well aware of the conservative control method: flooding. As with many roofing experts, however, skepticism predominates here too. In addition to the risks and the lack of precision, roofer Frank Lenser is particularly critical of the applicability: „We’re talking about well over 10,000 m2 of roof surface – there are only two throats where a drainage system runs off. This hall has a span of 100 m – I think flooding is too dangerous. We have a height difference of about one meter from the eaves to the ridge, so you can imagine how much water and weight would fit on it.“
Frank Lenser is now taking his first steps over the roof. The app finds the installed sensors every second. A short beep and the display says: „Sensor found, sensor dry.“
The roofer accelerates his step: „Sensor found, sensor dry“, „Sensor found, sensor dry“, it goes on and on. Foreman Lenser, who is working with a wireless control system for the first time, is amazed at how quickly the data is transmitted: „I didn’t think the scanner would reach this far and capture so many sensors without me having to answer directly. Within 10 minutes, the roofer had completely checked the roof area to be inspected: „160 sensors – all dry.“ Although Frank Lenser had reckoned with the result, the electronic confirmation of his gut feeling is still important to him: „We closed the roof every day and protected the insulation, so I was actually pretty sure that there was no wet spot in the roof. When we just walked over it, the device now proved to us that the insulation had been installed in a dry state and is still in a dry state“.
An economic consideration
The sensor system was included in the tender at the request of the client and the planner. For those responsible, this step was a purely economic consideration: It is expected that regular sensor scans during roof maintenance will contribute to being able to react faster than before to damage to the flat roof that cannot be detected with the naked eye. This is because wetness and standing water in the insulation often trigger a chain reaction, whereby entire areas of the roof can be under water within a short period of time. A scenario that exhibition hall 27 in particular cannot afford, but it should be able to be used as a reliable alternative area in the coming, approximately 15 year long renovation period of the entire exhibition grounds. For the client – Messe Berlin GmbH – sensor control therefore plays an important role in the maintenance plan.
Let the Grand Opening come!
It is now 4 pm in Berlin, the sun is now unfolding its full power. Record temperatures are reached on the roof of exhibition hall 27. However, the hot phase of sensor control is long since over. Roofer Frank Lenser now sends the results of the electronic check to his boss via app. All sensors checked with the app that day showed „dry“. From the roofer’s point of view, nothing more stood in the way of the topping-out ceremony on August 1, 2018.
The roof of the new administration building of the Ziegler Group was fitted with a gradient insulation system, moisture detectors and a very robust roof membrane. Even though flat roofs are architecturally very trendy for single-family homes and often have no alternative for commercial buildings, a certain skepticism is noticeable among many carpenters.
This is not without reason, as a flat roof brings the risk of standing water with it – a phenomenon that caused a number of structural damages in the 1970s and 1980s and which carpenters are still confronted with today during renovations.
Further protection through moisture detectors in the roof cladding
Developments such as the pitched roof have defused the problem of standing water in recent years, and sealing membranes made of new materials have replaced the bitumen systems of the 1970s and 1980s. Among experts, flat roofs are therefore considered to be permanently safe today, provided they are executed professionally. In addition, the installation of moisture detectors in the roof cladding can provide further protection. This was the case with the Ziegler Group administration building in Plößberg presented here.
„We had never installed a wetness early warning system before“
Cutting the 100 × 30 mm slits for the moisture detectors into the plates was no problem. The installation of these detectors was a first for the carpentry shop: „Up to now, we had never installed an electronic early warning system for moisture in a roof,“ recalls Schuller. „In Plößberg, it was the client who, for safety reasons, commissioned us to install wireless and batteryless sensors from HUM ID at the level of the vapour barrier“.
Using a scanner, the detectors provide early warning of moisture in the roof – for example, in the event of capillary cracks. There are hardly any running costs because they do not consume energy, but are supplied with power inductively by the reader. To scan them, a company employee only has to systematically walk along the flat roof with the scanner in his hand. A visual and acoustic signal alerts him to moisture in the roof.
First released in magazine Mikado 08/2020, (Original)
In addition to roofs and facades, efficient leakage control can also be guaranteed in the future in underfloor heating systems, wet rooms, kitchen seals and floors.
The all new HUM-ID sensor „KD1“ is placed in the floor area directly below the seal. Thanks to the highly absorbent and conductive special fleece, not a drop of moisture escapes – whether at construction joints, within insulation layers or within shafts and facing layers. The readout of the sensors is done by the already known handheld reader, which allows a direct transmission of the data to your smartphone.
Generally, the installation of one sensor per square meter is recommended. Depending on the area of application and the materials used, object-related grid dimensions can also be used as a basis. At risk areas the sensors can also be installed at a smaller distance. The sensor can indicate wet or dry as often as required. The KD1 can be used for new buildings as well as for renovation.
The KD1 sensor is recommended for control in the following applications:
Heavy rainfall, sudden blizzards, masses of snow: extreme secular wether conditions can harm the flat roof of your construction project massively. Prevent irreversible damages from happening by integrate HUM-ID sensors into the construction.
The small, affordable and durable chips can be placed directly into the insulation without extra effort. Depending on your project specifics you can integrate as many sensors as you need.
In Germany, where HUM-ID system is the goto system for professional flat roof buildings, architects usually integrate one sensor per 1m2 for small roofs or rather one sensor per 2 m2 (medium sized roofs) or eben one sensor per 4 m2 (large and very large roofs).
The HUM-ID system helps you secure the buildings longevity especially when the project is not yet finished.
The system which contains of the sensors, a scanner and an app for your smart phone helps general contractors and roofers when it comes to quality proof.
Especially before the onset of winter with the HUM-ID system you can control weak points on the roof and check if water has crossed the sealing and entered the insulation. If you detect water, the HUM-ID app let’s you localize the weak spot thanks to visual and audio feedback. This gives roofers the chance to repair the problematic spot on the fly.
Once the sensors being integrated you can check the roof at any time. This makes it possible to generate an electronic proof that the roof is in best condition. The passive sensors do not need batteries or any wires. This might be the reason why HUM-ID is the No.1 insulation control system for flat roofs in Germany.
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