Waterproofing is the process of making an object, person or structure waterproof or water-resistant so that it remains relatively unaffected by water or resists the ingress of water under specified conditions. Such items may be used in wet environments or underwater to specified depths.
Water-resistant and waterproof often refer to resistance to penetration of water in its liquid state and possibly under pressure, whereas Damp proofing refers to resistance to humidity or dampness. Permeation of water vapour through a material or structure is reported as a moisture vapor transmission rate (MVTR).
The hulls of boats and ships were once waterproofed by applying tar or pitch. Modern items may be waterproofed by applying water-repellent coatings or by sealing seams with or .
Waterproofing is used in reference to building structures (such as , decks, or wet areas), watercraft, canvas, clothing ( or waders), electronic devices and paper packaging (such as for liquids).
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 , the roofing must be waterproof. Many types of waterproof membrane systems are available, including felt paper or tar paper with Asphalt concrete 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 are designed to be porous enough to let moisture escape. Walls also have or . 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:
Another specialized area of waterproofing is rooftop decks and balconies. Waterproofing systems have become quite sophisticated and are a very specialized area. Failed waterproof decks, whether made of polymer or tile, are one of the leading causes of water damage to building structures and personal injury when they fail. Major problems occur in the construction industry when improper products are used for the wrong application. While the term waterproof is used for many products, each of them has a very specific area of application, and when manufacturer specifications and installation procedures are not followed, the consequences can be severe. Another factor is the impact of expansion and contraction on waterproofing systems for decks. Decks constantly move with changes in temperatures, putting stress on the waterproofing systems. One of the leading causes of waterproof deck system failures is the movement of underlying substrates (plywood) that causes too much stress on the membranes, failing the system. While beyond the scope of this reference document, waterproofing of decks and balconies is a complex of many complimentary elements. These include the waterproofing membrane used, adequate slope-drainage, proper flashing details, and proper construction materials.
The penetrations through a building envelope must be built in a way such that water does not enter the building, such as using flashing and special fittings for pipes, vents, wires, etc. Some are durable, but many are unreliable for waterproofing.
Also, many types of are available to control water, gases, or pollution.
From the late 1990s to the 2010s, the construction industry has had technological advances in waterproofing materials, including integral waterproofing systems and more advanced membrane materials. Integral systems such as hycrete work within the matrix of a concrete structure, giving the concrete itself a waterproof quality. There are two main types of integral waterproofing systems: the hydrophilic and the hydrophobic systems. A hydrophilic system typically uses a crystallization technology that replaces the water in the concrete with insoluble crystals. Various brands available in the market claim similar properties, but not all can react with a wide range of cement hydration by-products and thus require caution. Hydrophobic systems use or even to block pores within the concrete, preventing water passage.
Sometimes, the same materials used to keep water out of buildings are used to keep water in, such as a pool or .
New membrane materials seek to overcome shortcomings in older methods like polyvinyl chloride (PVC) and high-density polyethylene (HDPE). Generally, new technology in waterproof membranes relies on polymer-based materials that are very adhesive to create a seamless barrier around the outside of a structure.
Waterproofing should not be confused with roofing material, since roofing cannot necessarily withstand hydrostatic head while waterproofing can.
The standards for waterproofing bathrooms in domestic construction have improved over the years, due in large part to the general tightening of building codes.
Waterproof garments are intended for use in weather conditions which are often windy as well as wet and are usually also wind resistant.
Footwear can also be made waterproof by using a variety of methods, including but not limited to, the application of beeswax, waterproofing spray, or mink oil.
A 2013 study found that nanotextured surfaces using cone forms produce highly water-repellent surfaces. These nanocone textures are superhydrophobic (extremely water-hating).
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