how can we distinguish between brick cracking due to roof or parapet wall leaks and brick cracking due to thermal movement: a leak and frost related crack on a masonry building tends to be horizontal near the top of the building wall at about the location of the roof surface behind the parapet wall, or just below that point - describing where
notched floor joists for services, doorways cut through trussed partitions, partly-removed chimney-breasts and overloaded floors are the most popular abuses of buildings. many such alterations become obscured over the years, and it is only investigative work that will uncover the cause of the distortion (see sktch 3).
failing to permit movement of abutting or connected building materials whose rate of thermal expansion varies significantly will lead to separation, cracks, leaks, or damage in many instances. examples of the problems caused by differences in thermal expansion of building materials are particularly seen in windows and skylights.
floor finish slows water movement but does not stop moisture passage into or out of the flooring completely, so wet floors that have finish on them dry out slowly. as wood responds to environmental changes, the boards in a floor can experience forces from adjacent boards and from the subfloor.
therefore, thermal control is an important aspect in almost all buildings. understanding heat transfer and the temperature distribution through building materials and assemblies is also important for assessing energy use, thermal comfort, thermal movements, durability, and the potential for moisture problems.
5. species affects the amount of movement. wood movement depends in part on the species. a 12-in. wide western red cedar board will fluctuate 1/8 in. while the same size maple board will fluctuate 1/4 in. the formula for calculating wood movement is complex and extremely accurate, but tedious.
wood floors are prone to movement. installed correctly, floorboards hold tight to one another during humid times of the year and might reveal gaps during drier times. abnormal gaps are generally the result of flooring that’s too wet when it is installed (sidebar p. 80), but they also can be the consequence of installing flooring in areas of
thermal bridging is the movement of heat across an object that is more conductive than the materials around it. the conductive material creates a path of least resistance for heat. thermal bridging can be a major source of energy loss in homes and buildings, leading to higher utility bills.