Each downpipe in the building serving as a vent line has to protrude over the roof. alwitra stack vents form the upper end of vent lines over covered roofs of any constructional type. alwitra cold roof vents ensure air circulation in the air space of ventilated roof structures, so called cold roofs.
In the case of refurbishment, alwitra refurbishment vents offer an easy and reliable possibility of flashing existing vent lines up to DN 150 against the new waterproofing without prior removal.
Flat roof vents
New: alwitra vent stack
Wastewater downpipes in the building serving as vent lines must protrude over the roof. The alwitra vent stack forms the upper end of vent lines protruding over low slope roofs with waterproofing of any constructional type up to DN 125 (OD 125).
The vent stack consisting of one single pipe extends over the whole roof build-up without any joints and is connected to the downpipe DN 125 (OD 125) and DN 100 (OD 110) below the roof structure by means of the included reducer. A corresponding reducer (125/75) is available for downpipes DN 70 (OD 75).
The EVALON® or EVALASTIC® flashing collar is fitted to the vent stack at the factory and doubly secured by means of an external air padding (diving bell effect) protecting the connection. The flashing collar can be welded directly to the corresponding roof sealing without any auxiliary materials. At the top, the vent stack can be left open. Alternatively, the vent stack can be covered against rain with the included vent cowl or with the optional weather cap.
The lower part made of PP and PP bead foam is installed in the supporting substructure and flashed against the vapour and wind barrier; inserting into the vent pipe ensures air-tightness.
alwitra refurbishment vent 160
In the case of refurbishment, the thermally insulated alwitra refurbishment vent 160 offers an easy and reliable possibility of flashing existing vent lines up to DN 150 (OD160) against the new waterproofing without prior removal.
It is placed over the existing and cut-to-length (if required) vent pipe, which has to protrude at least 15 cm over the new waterproofing (or protection layers), and reliably fastened to the substrate (e.g. with screws in the respective places).
The remaining space between the existing vent pipe and the refurbishment vent is filled with several layers of PUR installation foam and at the top sealed with a permanently elastic sealant, so that possible condensate will drain off into the existing vent line without causing any damage.
The alwitra refurbishment vent 160 is made of CFC free PUR integral foam. At the factory, an EVALON® or EVALASTIC® sealing ring is foamed into the welding flange. The sealing ring ensures permanently reliable flashing against the new roof waterproofing. To this end, a prefabricated EVALON® or EVALASTIC® flashing collar is homogeneously welded to the sealing ring and the adjacent roofing membrane in the same way as the seam connection of the field membranes.
Other roofing membranes can be bonded to the 12 cm wide flange, also with hot bitumen. The vent cowl can be easily fitted and snapped into the pipe collar with four tabs. The vent cross section has a top and lateral cover to protect against heavy rain. Condensate forming on the vent cowl (if any) will drip off without causing any damage, partly into the existing vent pipe.
alwitra cold roof vent
alwitra cold roof vents facilitate air circulation in the air layer of ventilated roof structures, so called cold roofs. Only sufficient air exchange over the whole area will ensure long-term functionality of a cold roof.
As with the vent stack, the EVALON® or EVALASTIC® flashing collar is fitted to the vent pipe at the factory and doubly secured by means of an external air padding (diving bell effect) protecting the connection. It can be welded directly to the corresponding roof sealing without any auxiliary materials.
The vent cowl, together with the weather cap, provides rainproof covering of the vent pipe. At the lower end of the vent, a drip pan will collect any condensate, which will eventually evaporate. This is to prevent or reduce moisture penetration of the thermal insulation. Ventilation is provided for by slots regularly arranged around the vent, with a vent cross section of ~110 cm2.
Overview of important downloads
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