Environmental considerations include such factors as the physical state of moisture present liquid, solid, or vaporair movement, and temperature extremes as well as temperature differentials. For example, in the liquid state, water penetrating to the interior of a building may cause considerable damage to its contents. In some extreme cases, water trapped within the masonry may freeze, inducing spalling and cracking of the masonry units or mortar.
Flashing refers to thin pieces of impervious material installed to prevent the passage of water into a structure from a joint or as part of a weather resistant barrier system. In modern buildings, flashing is intended to decrease water penetration at objects such as chimneysvent pipes, walls, windows and door openings to make buildings more durable and to reduce indoor mold problems. Metal flashing materials include leadaluminiumcopper stainless steelzinc alloyand other materials.
For cavity walls, as illustrated in Figure 1, the cavity typically ranges from a minimum of 2 in. If precautions are not taken, it is suggested that a wider airspace be utilized, i. Also when using glazed masonry veneer, a 2 in.
Photograph 2: Wood cant at corner. Photograph 3: Cementitious cant at curved substrate. Cants installed at inside and outside corners of walls should be constructed with mitered corners at the ends of the mating cant pieces. Forming smooth mitered corners is difficult to achieve with wood due to the rough, sharp edges formed by the saw-cutting process and the rigidity and trueness of both the wood and the underlying substrate reference Photograph 2.
Log in or register to create Field Kits and Sales Worksheets. Why register? Install flashing integrated with air and water control layers around piping, vents, and other wall penetrations as part of an exterior wall retrofit as follows:.
The following range of flashings have proven to be universally popular and suitable for most applications. Minor local variations may exist from that shown. Dimensions are nominal and may vary with changes in material.
Successful flat roof systems and roofing membranes are usually possible if building science principles are understood and applied to design and construction. Difficulties occur, however, when the designer fails to appreciate the necessity to detail the complete waterproofing system. The details of interruptions and terminations of the membrane at ancillary features are of such particular importance that their selection and manner of construction should not be left to the discretion of a material supplier or a tradesman at the job site.
Gravity is the driving force behind drainage. In general, the sooner water is directed out the better. Sooner, may not always be practical—such as at window openings where draining a window into a drainage space behind a cladding is often more practical than draining them to the exterior face of the cladding. The most elegant expression of this concept is a flashing see Roof to Wall Flashing with Foam Sheathing.
Description : Through-wall flashing is used to divert moisture, which has entered the wall, to the outside, before it can cause damage. This flashing method is considered the most satisfactory method of preventing leaks except in areas exposed to earthquakes. Through-wall flashing is used at all points where moisture may enter the wall, and in selected places particularly susceptible to water damage.
Log in or register to create Field Kits and Sales Worksheets. Why register? Install step and kick-out flashing at all roof-wall intersections to protect walls from water intrusion and install boot or collar flashing at all roof penetrations to protect roofs from leaks. In multi-level house designs where roofs intersect walls, much of this water is channeled along the wall to a gutter.