As we progress through the new millennium, we are becoming accustomed to seeing stormy weather images on our TV’s and reading news articles. Most homeowners at some time will have experienced some sort of damage resulting from extreme weather conditions. Wind damage to roofs and the associated damage caused by loose tiles is common in the UK. Whether this can be attributed to climate change or not the incidence of such events is becoming more common. A system of colour coded weather warnings has been established by the MET office to give the general public time to prepare for severe or hazardous weather. A guide which would help to limit storm damage to our homes would therefore make good sense - this is where the new BS5534 document steps in.
The latest revision to BS5534, effective from March 2015 is a radical update to the standard with a realistic and future - proof emphasis on roof security and overall safety. The document addresses in detail the specification of mortar bedding, battens, flashings, structural sheathing and underlays as well as a specific focus on fixings. BS5534: 2014 also includes guidance associated with UK meteorological data, such as exposure to driving rain and a noticeable concentration on the effect of wind pressures on roofing components. Roofing underlays have not been left out and now after many years of debate specific limits on wind uplift resistance have been imposed.
By following the guidance and advice given in the standard we can now realistically design and build our homes in a way to better prepare them for high winds and stormy conditions.
The wind uplift resistance figures for the Tyvek® underlay stated apply to applications where a well-sealed ceiling is present, ridge height is not greater than 15 m, roof pitch is between 12.5° and 75°, site altitude is not greater than 100 m, and no significant site is present. Projects outside of these parameters may require a greater wind uplift resistance.
Tyvek® - unrestricted use:
Our current Tyvek® pitched roof underlays listed below have been subjected to the test procedures concerning wind uplift outlined in the recent revision to BS5534 (Code of practice for slating and tiling). A Tyvek® underlay with a taped lap will satisfy all geographical locations, all site conditions and all building characteristics.
These products are currently available, are fully BBA certified and have full CE marking and Declaration of Performance (DoP) as required under the Construction Products Regulations 2013.
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