Rainscreen
Encyclopedia
A rainscreen is the exterior weather
-facing surface of an exterior wall
detail that stands off from the moisture
-resistant
surface of the structural backup wall. The rainscreen is the first interruption between conditions that exist on the outside of a walled building and conditions that are required on the inside of a walled building. A veneer
that does not stand off from the moisture-resistant surface of the structural backup wall to create a cavity
is not a true rainscreen. However, a masonry veneer can be a rainscreen.
In a rainscreen the air gap allows the circulation of air across the air vapour barrier. This helps remove condensation and helps direct water away from the dry insulation where it otherwise might cause problems such as mould formation and water leakage. The Air Vapour barrier prevents water molecules from entering the insulated cavity but allows the passage of air.
The air gap is created using steel hatbars fastened vertically to a series of horizontal spanning subgirts. The hatbars also provide a fastening surface for the facade panels. An EPDM gasket is placed between the facade panels and the hatbars to prevent rain water from entering the ventilation channel created by the hatbars. The gasket directs water away and toward special drip edge flashings which further protect other parts of the building.
The hatbars are connected to the horizontal subgirts with a permeable air vapour barrier in between. Behind the air vapour barrier, there is often space for different varieties and thicknesses of insulation. The thickness of insulation is determined by building code requirements as well as performance requirements set out by the architect.
s including concrete
, terra cotta
, clay, porcelain
, galvanized steel, aluminum, thin stone panels, thin-brick panels and polyurethane
.
Weather
Weather is the state of the atmosphere, to the degree that it is hot or cold, wet or dry, calm or stormy, clear or cloudy. Most weather phenomena occur in the troposphere, just below the stratosphere. Weather refers, generally, to day-to-day temperature and precipitation activity, whereas climate...
-facing surface of an exterior wall
Wall
A wall is a usually solid structure that defines and sometimes protects an area. Most commonly, a wall delineates a building and supports its superstructure, separates space in buildings into rooms, or protects or delineates a space in the open air...
detail that stands off from the moisture
Moisture
Humidity is the amount of moisture the air can hold before it rains. Moisture refers to the presence of a liquid, especially water, often in trace amounts...
-resistant
Hydraulic conductivity
Hydraulic conductivity, symbolically represented as K, is a property of vascular plants, soil or rock, that describes the ease with which water can move through pore spaces or fractures. It depends on the intrinsic permeability of the material and on the degree of saturation...
surface of the structural backup wall. The rainscreen is the first interruption between conditions that exist on the outside of a walled building and conditions that are required on the inside of a walled building. A veneer
Masonry Veneer
Masonry veneer walls consist of a single non-structural external layer of masonry work, typically brick, backed by an air space. The innermost element is usually structural, and may consist of wood or metal framing or masonry...
that does not stand off from the moisture-resistant surface of the structural backup wall to create a cavity
Cavity
A cavity is a hole. It may refer to:*Dental cavity, damage to the structure of teeth*Body cavity, a fluid filled space in many animals where organs typically develop*Cavity wall, a wall consisting of two skins with a cavity....
is not a true rainscreen. However, a masonry veneer can be a rainscreen.
In a rainscreen the air gap allows the circulation of air across the air vapour barrier. This helps remove condensation and helps direct water away from the dry insulation where it otherwise might cause problems such as mould formation and water leakage. The Air Vapour barrier prevents water molecules from entering the insulated cavity but allows the passage of air.
The air gap is created using steel hatbars fastened vertically to a series of horizontal spanning subgirts. The hatbars also provide a fastening surface for the facade panels. An EPDM gasket is placed between the facade panels and the hatbars to prevent rain water from entering the ventilation channel created by the hatbars. The gasket directs water away and toward special drip edge flashings which further protect other parts of the building.
The hatbars are connected to the horizontal subgirts with a permeable air vapour barrier in between. Behind the air vapour barrier, there is often space for different varieties and thicknesses of insulation. The thickness of insulation is determined by building code requirements as well as performance requirements set out by the architect.
Materials
Rainscreens are constructed from many different materialMaterial
Material is anything made of matter, constituted of one or more substances. Wood, cement, hydrogen, air and water are all examples of materials. Sometimes the term "material" is used more narrowly to refer to substances or components with certain physical properties that are used as inputs to...
s including concrete
Concrete
Concrete is a composite construction material, composed of cement and other cementitious materials such as fly ash and slag cement, aggregate , water and chemical admixtures.The word concrete comes from the Latin word...
, terra cotta
Terra cotta
Terracotta, Terra cotta or Terra-cotta is a clay-based unglazed ceramic, although the term can also be applied to glazed ceramics where the fired body is porous and red in color...
, clay, porcelain
Porcelain
Porcelain is a ceramic material made by heating raw materials, generally including clay in the form of kaolin, in a kiln to temperatures between and...
, galvanized steel, aluminum, thin stone panels, thin-brick panels and polyurethane
Polyurethane
A polyurethane is any polymer composed of a chain of organic units joined by carbamate links. Polyurethane polymers are formed through step-growth polymerization, by reacting a monomer with another monomer in the presence of a catalyst.Polyurethanes are...
.