Water-resistant and waterproof often refer to resistance to penetration of water in its liquid state and possibly under pressure, whereas damp proof refers to resistance to humidity or dampness. Permeation of water vapour through a material or structure is reported as a moisture vapour transmission rate (MVTR).
The hulls of boats and ships were once waterproofed by applying pitch . Modern items may be waterproofed by applying water-repellent coatings or by sealing seams with o-rings.
Waterproofing is used in reference to building structures (such as decks, or wet areas), watercraft, canvas, clothing, electronic devices and paper packaging (such as cartons for liquids)
In construction, a building or structure is waterproofed with the use of membranes and coatings to protect contents and structural integrity. The waterproofing of the building envelope in construction specifications is listed under 07 - Thermal and Moisture Protection within MasterFormat 2004, by the Construction Specifications Institute, and includes roofing and waterproofing materials
In building construction , waterproofing is a fundamental aspect of creating a building envelope , which is a controlled environment. The roof covering materials, siding , foundations, and all of the various penetrations through these surfaces must be water-resistant and sometimes waterproof. Roofing materials are generally designed to be water-resistant and shed water from a sloping roof, but in some conditions, such as ice damming and on flat roofs, the roofing must be waterproof. Many types of waterproof membrane systems are available, including felt paper or tar paper with asphalt or tar to make a built-up roof, other bituminous waterproofing , ethylene propylene diene monomer EPDM rubber, hypalon, polyvinyl chloride, liquid roofing, and more. Walls are not subjected to standing water, and the water-resistant membranes used as housewraps are designed to be porous enough to let moisture escape. Walls also have vapour barriers or air barriers. Damp proofing is another aspect of waterproofing. Masonry walls are built with a damp-proof course to prevent rising damp, and the concrete in foundations needs to be damp-proofed or waterproofed with a liquid coating, basement waterproofing membrane (even under the concrete slab floor where polyethylene sheeting is commonly used), or an additive to the concrete.
Within the waterproofing industry, below-ground waterproofing is generally divided into two areas:
● Tanking: This is waterproofing used where the below-ground structure will be sitting in the water table continuously or periodically. This causes hydrostatic pressure on both the membrane and structure and requires full encapsulation of the basement structure in a tanking membrane, under slab and walls.
● Damp proofing: This is waterproofing used where the water table is lower than the structure and there is good free-draining fill. The membrane deals with the shedding of water and the ingress of water vapour only, with no hydrostatic pressure. Generally, this incorporates a damp proof membrane (DPM) to the walls with a polythene DPM under the slab. With higher grade DPM, some protection from short-term Hydrostatic pressure can be gained by transitioning the higher quality wall DPM to the slab polythene under the footing, rather than at the footing face.
Waterproofing methods have been implemented in many types of objects, including paper packaging, cosmetics, and more recently, consumer electronics. Electronic devices used in military and severe commercial environments are routinely conformally coated in accordance with IPC-CC-830 to resist moisture and corrosion but encapsulation is needed to become truly waterproof. Even though it is possible to find waterproof wrapping or other types of protective cases for electronic devices, a new technology enabled the release of diverse waterproof smartphones and tablets in 2013. This method is based on a special nanotechnology coating a thousand times thinner than a human hair which protects electronic equipment from damage due to the penetration of water. Several manufacturers use the nano coating method on their smartphones, tablets, and digital cameras.
