New Tyvek® E-Guard W1 Provides Peace Of Mind On The Exposed Cliffs At Mevagissey

Case Study
Case Study
New Tyvek® e-Guard W1 provides peace of mind on the exposed cliffs at Mevagissey

Tyvek® e-Guard W1 provides peace of mind


Situated on the cliffs at Mevagissey, new build housing by Cornwall Timber Build benefits from the multiple qualities of new Tyvek® e-Guard W1, a metallised breather membrane with high thermal values and above W1 water hold out.


Any high-spec timber build demands the very best in envelope protection, both during construction and once occupied, but particularly in places of great exposure from the elements. When Cornwall Timber Build came to specify a suitable reflective breather membrane for the walls of a new housing development on the rugged Cornish coastline, they found that only new Tyvek® e-Guard W1 ticked all the right boxes.

This means that, in addition to excellent low emissivity values, the project also benefits from superior UV resistance while the membranes are uncovered, plus enhanced airtightness, and crucially, complete confidence in water hold out (at above TRADA recommendations). All these advantages come naturally to Tyvek®, which has demonstrated its reliable performance time and time again, both in rigorous testing and over many years in the field.


New Tyvek® e-Guard W1 for walls occupies a unique position in the market by offering above W1 water hold out. TRADA recommends W1 as a minimum for sites of the level of exposure of this location. Cliff Road in Mevagissey, as the name suggests, is situated on high ground and at the mercy of all the variety and power of the Atlantic weather. Tyvek® e-Guard W1 delivers an impressive 1.7m water column, a near passive standard of airtightness, resistance to four months UV exposure, and all the dependable vapour permeability for which the leading brand is famed.

In terms of reflective capacity, metallised Tyvek® e-Guard W1 is certified as having a thermal resistance value for all cavi­ties larger than 20mm of 0.75 m2K/W (using the NPL guarded hotbox method) and reflects 95% of heat radiation, providing interior comfort throughout the year. The product has also recently been granted STA AssureGold accreditation

“When the building components for the site were being prepared in the factory,” says Stuart Dewey of Cornwall Timber Build, “we knew that the location was classified as severe exposure. This limited our choice of breather membrane to those with a W1 or better water hold out. Most metallised membranes offer only a W2 (50mm water column) rating but Tyvek® e-Guard W1 is far superior. In fact, its 1.7m water head means that we can use this material all over Cornwall and the rest of the UK, in any type of geography, while meeting and even exceeding industry guidelines.”

There are five 200 square metre plots in the Mevagissey development, offering high quality timber frame homes, with external finishes varying between natural slate and block and render. Eventual occupants can look forward to enjoying not only the beauty of their location, but also comfortable interior conditions and lower energy bills, even if the weather outside is travelling through Cornwall’s traditional extremes.