The gas production is made in the degisters in the biogas facilities. Gas is formed after passing through certain processes, from the liquid fertilizer and organic wastes, pumped inside the degisters. It is required to made gas proof roof on it for the gas formed not escaping from the degisters having circular cross-sections. However this roof should be made up of elastic material. The flexible roof expands and the degister volume increase for not increasing the pressure in the gas formation inside the degister. It is required that the pressure inside the degisters stays in minibar levels. Otherwise, gas explosions occur. Because of this degister roofs are covered with EPDM membranes which are very flexible. The locking points inside the concrete are provided by PVC profiles produced specially.