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How many Cor-Vent® Strips do I need?

3 mins read 21 May 2026
Cor-Vent® 25K BAL

Passive roof ventilation plays an important role in helping improve airflow and reduce condensation risk within roof spaces. But when it comes to installation planning, one of the most common questions is simple: How many Cor-Vent® Strips do I need? In this guide, we explain an easy way to estimate Cor-Vent® strip quantities for both low-level and high-level roof ventilation applications so you can specify and order with confidence.

How many Cor-Vent® Strips do I need?

We have created some simple steps to make calculating roof ventilation product requirements simple; less NCC maths, more “measure → divide → order”.

Here are some instructions to provide you with a quick and easy method to calculate how many Cor-Vent® Strips are required for your roof build.

Step 1

Measure the required ventilation length on your roof.

  • Low level ventilation (eaves) – Measure both roof sides
  • High level ventilation (ridge / parapet / upper ventilation point) – Measure the ridge or high-level ventilation area

Step 2

Divide by the Cor-Vent® Strip length.

Product
Strip Length
Formula
Cor-Vent® 8K / 25K 2.5m Required metres ÷ 2.5
Cor-Vent® 5K 100 (High Level) 1.2m Required metres ÷ 1.2

 

Always round up to the next whole strip.

Example

Example – Standard Hip Roof

  • Longest roof dimension = 20m
  • Low level ventilation – Cor-Vent® 8K
  • 20m × 2 sides = 40m required

40 ÷ 2.5 = You require 16 x Cor-Vent® 8K Strips


  • High level ventilation – Cor-Vent® 5K
  • 10m ridge length
  • 10 ÷ 1.2 = 8.3 strips

Round up = You require 9 x Cor-Vent® 5K Strips


Project total:

16 × Cor-Vent® 8K + 9 × Cor-Vent® 5K

Another option

Need an even quicker calculator? Try this!

Quick Cor-Vent® Strip Calculator

  • Cor-Vent® 8K / 25K (Low Level)
  • Roof length × 2 ÷ 2.5 = Cor-Vent® Strips required
  • Cor-Vent® 5K 100 (High Level)
  • Ridge length ÷ 1.2 = Cor-Vent® Strips required

Round up to the nearest whole strip.

Installation & more support

Cor-Vent® product installations do not require any special tools, training, or major changes to the roof build. Cor-Vent® Installation Guides are included in the Product Information Download Forms on this page.

Download installation guides

Certification

Cor-Vent® meets the DTS airflow opening requirements per NC2022, including BAL Zones.

For more support, contact our Cor-Vent® specialists for additional information building@corex.com.au

Above: Cor-Vent® STANDARD 8K 200