New wind calculator tool from Tyvek® helps to calm the storm

Roofers request a new, easy-to-use wind uplift calculator to determine correct roofing underlays.

By Bradley Cameron
Technical Manager, Tyvek® and AirGuard® Building Knowledge Centre

Roofing contractors take pride in professional installations that can stand the test of time. Selecting the correct roofing underlay is critical – getting it wrong could be expensive in many ways.

A crucial quality is the ability to withstand ‘underlay ballooning’ where impact with the outer covering can dislodge the tiles or slates and cause injury, considerable damage or risk of water ingress. Identifying the best membrane for the job can be tricky, which makes a useful new wind uplift calculator tool an indispensable source of advice.

Relying on the five BS5534 wind zones alone is insufficient.

The BS5534 standard splits the UK into five zones, each with a different requirement of resistance to wind uplift. However, using this method alone risks allowing materials with insufficient strength to be used when they are not suitable as the zonal approach does not take into account a number of requirements of the standard. These include site altitude, ridge height, pitch, site topography, ceiling condition, proximity to a body of water, slope on site and rural or town location.

The standard, when applied as written, does distinguish between the unrestricted membranes available (such as Tyvek® Supro with a taped lap) and materials with a very restricted use across the UK. The test itself is based around traditional installation techniques and the use of an expensive-to-fit counter batten is not shown or described in the test method. If a counter batten is used on refurbishment work, it will alter all the facia and gable heights etc., creating even more work and expense.

We are all familiar with the term “buyer beware” and this is certainly the case in this instance. Key phrases such as “BS5534 compliant”, “specifications available” or “all zones compliance” may offer a sense of security, but when used without the certified wind uplift figure, mean very little in terms of performance.

The new wind uplift calculator tool: a more accurate assessment for better outcomes

DuPont™ Tyvek® offers a new, tried and tested wind uplift calculator tool that goes beyond BS5534 zonal criteria. It’s quick, easy to use, and it’s free. Just enter the relevant information by selecting drop downs in seven categories:

  • Country (England, Scotland or Wales)
  • Wind zone (from the five wind zones identified in BS5534)
  • Terrain
  • Building height
  • Ceiling type
  • Distance from water (sea, lakes, rivers, etc.)
  • Slope

Almost instantly, it will assess individual aspects and recommend the membrane best suited for the job… and every project, whatever its location, is unique. Determining the correct roofing membrane that will be durable over the years is important to any roofer’s professional reputation, their peace of mind and the building owners’ financial risk. The Tyvek® Knowledge Centre BS5534 Wind Uplift Calculator is also now BRE tested and calibrated as accurate and in full compliance with all the requirements of BS5534, currently a unique stamp of approval.

For more information on Tyvek® airtightness systems or to access the new wind uplift calculator, visit Alternatively, please contact Bryn Thomas at the Tyvek® & AirGuard® Building Knowledge Centre on 0844 406 8722 or via ‘Contact Us’ on the website.