For Flat, Curved & Sloping Roofs

For Flat, Curved
& Sloping Roofs

25 Year Guarantee

25 Year

Specialist Advice & Support

Specialist Advice
& Support

Express National Delivery

Express National

We've waterproofed 180m SqM of roofs!

We've waterproofed
180m SqM of roofs!

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a sample

Cold Roof Vents
Cold Roof Vents

alwitra® cold roof vents can be welded directly to the corresponding roof waterproofing without any additional materials.

  • The vent cowl, together with the weather cap, provides rainproof protection 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

Cold Roof Vents

The alwitra® Cold Roof Vents facilitate air circulation in the cavity of ventilated roof structures, so called cold roofs. Only sufficient air exchange over the whole area will ensure longterm functionality of a cold roof.


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 EVALON®® connecting flange is factory fitted to the vent pipe and doubly secured by means of an external air cushion cell (diving bell effect) protecting the connection


  • Suitbale for both warm and cold roofs

Product Details Back to top

Product Specification

Material: PVC pipe with condensate drip pan, vent cowl and weather cap made of PP
Colour: Black, with factory-fitted connecting flange in the colour of the waterproofing membrane
Height above the waterproofing (excl. vent grate/weather cap): 300 mm
Outer pipe diameter: 125 mm (DN 125)
Outer connecting flange diameter: 480 mm
Outer flange diameter: 240 mm
Ø of screw holes at flange:  210 mm
Flange width:  60 mm
Installation opening: Ø 150 mm
Installation depth from flange: approx. 140 mm
Vent cross section: ~ 110 cm2

Technical Drawings

Cold Roof Vents
Cold Roof Vents

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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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Contact Us 01202 785200

Here's what some of our clients have to say...

We have been alwitra® contractors for many years and have always been impressed with the results and reliability of the product. The customers…

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I, James Hopkins Director of JH Specialist Roofing install single-ply membranes on a daily basis, we as a company have tried numerous types of…

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We have used VSK extensively over the last 5 years, we have found it to be a great product and really good for complex detail work. We find using…

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As a small flat roofing business carrying out mostly domestic refurb work and small extensions EVALON® VSK is our preferred single ply membrane…

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We have been an approved contractor for many years, the level of customer service and the quality of the products provided by ICB (Waterproofing) is…

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We have worked with ICB on several occasions and we would thoroughly recommend them for their high level of professionalism and efficiency. The team…

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OB Architecture

ICB provides an excellent service with all the professional back-up required at the development stage through to completion. The manner in which you…

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I am pleased to recommend ICB as Company, through my personal experience and that of my Business, for the following reasons: They are an easy Company…

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We believe, as one of your approved contractors, over the years we have had a great working relationship with yourselves. When working on projects…

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Best system on the market – VSK all the way!!!!!!


alwitra® is a lovely membrane when you have some detailing and gutters as you can go all the way through in a oner…


…that’s the beauty of this membrane, (you) can complete field sheet and upstand in one go, nice and tight and (a) crisp finish in the…

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This product has to be the most versatile single-ply system we have used. Unbeatable finish.

Lee Orchard

EVALON® VSK – such a quality and versatile membrane.

Lee Orchard

In my mind the best single-ply.


Can’t beat VSK


We find all the staff at ICB, friendly, helpful & knowledgeable.


EVALON® VSK! Surely the best single-ply waterproofing membrane ever produced! A++++


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