For Flat, Curved & Sloping Roofs

For Flat, Curved
& Sloping Roofs

25 Year Guarantee

25 Year

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Specialist Advice
& Support

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Express National

We've waterproofed 180m SqM of roofs!

We've waterproofed
180m SqM of roofs!

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Soil Vent Pipes
Soil Vent Pipes

The alwitra® soil vent pipe forms the upper end of vent pipes protruding over low slope roofs with waterproofing of any constructional type up to DN 125 (OD 125).

  • The soil vent pipe consisting of one single pipe extends over the 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 connecting flange can be made with EVALON®

Soil Vent Pipes

The alwitra® Shaft (Soil) Vent Pipe forms the upper end of vent pipes protruding over low slope roofs. The soil vent pipe consisting of one single pipe extends over the roof build-up without any joints and is connected to the downpipe.e below the roof structure by means of the included reducer.


As used on landmark architecture throughout the world

almost 40 years experience with waterproofing systems in the UK

Almost 40 years experience with waterproofing systems in the UK

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  • The connecting flange can be welded dirtectly to the corresponding roof waterproofing without any auxiliary materials.
  • At the top, the soil vent pipe can be left open. Alternatively, the soil vent pipe 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


  • Suitable for both warm and cold roofs

Product Details Back to top

Product Specification

Material: PVC pipe with vent cowl and optional weather cap made of PP
Colour: black, with factory-fitted connecting flange in the colour of the waterproofing membrane
Height above the waterproofing (excl. cowl): 300 mm
Outer pipe diameter: 125 mm (DN 125)
Outer connecting flange diameter: 480 mm
Outer support ring diameter: 240 mm
Ø of screw holes at support ring: 210 mm
Flange width support ring: 60 mm
Installation opening: Ø 190 (200) mm
Thermal insulation thickness: 0 - 300 mm (or 800 mm for SL)
Connection diameter: 125 mm (DN 125) and 110 mm (DN 100), 75 mm (DN 70) optional

Technical Drawings

Soil Vent Pipes

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Our membranes are used by architects, contractors & developers. View all

Archdiocese of Liverpool
Coventry City Council
3D Reid
Balfour Beatty
InFrame Garden Rooms
Fife Council
Angell Thompson
Alec French Architects
Aloft Roofing & Leadwork
English Heritage
Glasgow Housing Association
Coomber Associates
Ashtree Roofing

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