Quotes: Dew Point Analysis vs. Hygrothermal Simulation

On Steady State/Dew Point Assessment (Glaser Method): BS EN ISO 13788:2002 Section 6.1 This standard gives calculation methods for: a) The internal surface temperature of a building component or building element below which mould growth is likely, given the internal temperature and relative humidity – the method can also be used to assess the risk…

Extreme Climatic Events

Extreme Climatic Events Provide Important Insights For Resilient Design

Extreme climatic conditions are those falling in the upper or lower tenth percentile of the local period of record. North American hygrothermal datasets rely on such extremes in simulating climatic effects on building performance. Prior to 2012, WUFI employed customized 30-year hourly data provided by the U.S. Department of Energy for the 1961-1990 period of…

Moisture Performance Of An All-Wood R-30 Wall

Natural alternatives to foam insulation are highly desirable for high-performing wood-framed buildings.  But lignocellulosic materials can be highly bio-nutritive and moisture absorptive, increasing their vulnerability to degradation and reduced thermal performance.  Designers are often faced with the dilemma of selecting materials that are less environmentally safe for much improved performance.  In this article, I describe a…

Degradation of Fiber Cement Siding

Degradation Of Medium-Density Fiber Cement Siding

Fiber cement cladding has found wide acceptance as a durable and renewable material.   Since entering the U.S. market in the early 1990s, assumptions on its long-term resiliency have relied heavily on wet/dry cycling tests, but little is reported on its durability under typical in-service conditions.   Here we describe four stages of fiber cement degradation under…

Is TimberSIL Resilient?

TimberSIL is a glass-infused wood manufactured by Timber Treatment Technologies.  Marketed as a green substitute to conventional chemically-treated wood, TimberSIL has come under recent scrutiny for questionable performance under intended designed conditions.  We use this situation to discuss the implications of vetting new products on the basis of green material ratings. Criticisms have emerged over the product’s susceptibility to rot and poor acceptance of common coatings.  Perhaps…

Performance Of Decay And Termite-Resistant Wood

In an earlier post, we reviewed standards and implications pertaining to mold-resistant construction materials (December 20, 2013).  We limited our discussion to some of the most widely used resistance tests performed under short-term, laboratory conditions.  Here, we take the discussion further by examining decay resistance tests for treated and untreated wood. Treated wood products provide an essential…

Quotes: Rainscreens

“… it can be concluded that the face seal systems evaluated  in this study are very sensitive to design and construction variables which  lead to ingress of water through the cladding, and that in the environment  of the Lower Mainland it may not be possible to achieve acceptable performance  with face sealed systems. Concealed barrier…