Damp proofing

Last updated
A metal damp proof course (DPC) between the stone foundation and brick wall Horizontalsperre nirostahl.jpg
A metal damp proof course (DPC) between the stone foundation and brick wall

Damp proofing in construction is a type of moisture control applied to building walls and floors to prevent moisture from passing into the interior spaces. Dampness problems are among the most frequent problems encountered in residences.

Contents

DPC visible between concrete foundation and brickwork. FlexibleRainPipe.JPG
DPC visible between concrete foundation and brickwork.

Damp proofing is defined by the American Society for Testing and Materials (ASTM) as a material that resists the passage of water with no hydrostatic pressure. [1] Waterproof is defined by the ASTM as a treatment that resists the passage of water under pressure. [1] Generally, damp proofing keeps exterior moisture from entering a building; vapor barriers, a separate category, keep interior moisture from getting into walls. Moisture resistance is not necessarily absolute; it is usually stated in terms of acceptable limits based on engineering tolerances and a specific test method.

Methods

Damp proofing is accomplished several ways including:

Materials

Materials widely used for damp proofing include: [6]

Masonry construction

A DPC is a durable, impermeable material such as slate, felt paper, metal, plastic or special engineered bricks [7] bedded into the mortar between two courses of bricks or blocks. It can often be seen as a thin line in the mortar near ground level. To create a continuous barrier, pieces of DPC or DPM may be sealed together. In addition, the DPC may be sealed to the DPM around the outside edges of the ground floor, completely sealing the inside of the building from the damp ground around it.

In a masonry cavity wall, there is usually a DPC in both the outer and inner wall. [8] In the outer wall it is normally 150 millimetres (5.9 in) to 200 mm (7.9 in) above ground level (the height of 2-3 brick courses). This allows rain to form puddles and splash up off the ground, without saturating the wall above DPC level. The wall below the DPC may become saturated in rainy weather. The DPC in the inner wall is usually below floor level, (under a suspended timber floor structure), or, with a solid concrete floor, it is usually found immediately above the floor slab so that it can be linked to the DPM under the floor slab. This enables installation of skirting boards above floor level without fear of puncturing it. Alternatively, instead of fitting separate inner and outer DPCs, it is common in commercial housebuilding to use a one-piece length of rigid plastic (with an angled section) that fits neatly across the cavity and slots into both walls (a cavity tray). This method requires weep vents to enable water to drain from the cavity, otherwise dampness could rise from above the DPC.

Concrete walls and floors

Concrete normally allows moisture to pass through so a vertical vapor barrier is needed. Barriers may be a coating or membrane applied to the exterior of the concrete. The coating may be asphalt, asphalt emulsion, a thinned asphalt called cutback asphalt, or an elastomer. [9] Membranes are rubberized asphalt or EPDM rubber. Rubberized products perform better because concrete sometimes develops cracks and the barrier does not crack with the concrete.

Remedial damp proofing

Until the 20th century, masonry buildings in Europe and North America were generally constructed from highly permeable materials such as stone and lime-based mortars and renders covered with soft water-based paints which all allowed any damp to diffuse into the air without damage. The later application of impermeable materials which prevent the natural dispersion of damp, such as tile, linoleum, cement and gypsum-based materials and synthetic paints is thought by some to be the most significant cause of damp problems in older buildings. [10]

There are many solutions for dealing with dampness in existing buildings, the choice of which will largely be determined by the types of dampness that are affecting the building, e.g., rising damp, hygroscopic damp, condensation, penetrating damp, etc.

In older buildings, damp stains on internal walls are usually due to external factors such as:

Health and safety

Some DPC materials may contain asbestos fibres. This was more commonly found in the older, grey sealants as well as flexible tar boards.

Related Research Articles

<span class="mw-page-title-main">Wall</span> Vertical structure, usually solid, that defines and sometimes protects an area

A wall is a structure and a surface that defines an area; carries a load; provides security, shelter, or soundproofing; or, is decorative. There are many kinds of walls, including:

<span class="mw-page-title-main">Mortar (masonry)</span> Workable paste which hardens to bind building blocks

Mortar is a workable paste which hardens to bind building blocks such as stones, bricks, and concrete masonry units, to fill and seal the irregular gaps between them, spread the weight of them evenly, and sometimes to add decorative colors or patterns to masonry walls. In its broadest sense, mortar includes pitch, asphalt, and soft mud or clay, as those used between mud bricks, as well as cement mortar. The word "mortar" comes from Old French mortier, "builder's mortar, plaster; bowl for mixing." (13c.).

<span class="mw-page-title-main">Basement</span> Below-ground floor of a building

A basement or cellar is one or more floors of a building that are completely or partly below the ground floor. Especially in residental buildings, it often is used as a utility space for a building, where such items as the furnace, water heater, breaker panel or fuse box, car park, and air-conditioning system are located; so also are amenities such as the electrical system and cable television distribution point. In cities with high property prices, such as London, basements are often fitted out to a high standard and used as living space.

<span class="mw-page-title-main">Stucco</span> Construction material made of aggregates, a binder, and water

Stucco or render is a construction material made of aggregates, a binder, and water. Stucco is applied wet and hardens to a very dense solid. It is used as a decorative coating for walls and ceilings, exterior walls, and as a sculptural and artistic material in architecture. Stucco can be applied on construction materials such as metal, expanded metal lath, concrete, cinder block, or clay brick and adobe for decorative and structural purposes.

<span class="mw-page-title-main">Siding (construction)</span> Exterior cladding on building walls

Siding or wall cladding is the protective material attached to the exterior side of a wall of a house or other building. Along with the roof, it forms the first line of defense against the elements, most importantly sun, rain/snow, heat and cold, thus creating a stable, more comfortable environment on the interior side. The siding material and style also can enhance or detract from the building's beauty. There is a wide and expanding variety of materials to side with, both natural and artificial, each with its own benefits and drawbacks. Masonry walls as such do not require siding, but any wall can be sided. Walls that are internally framed, whether with wood, or steel I-beams, however, must always be sided.

<span class="mw-page-title-main">Concrete block</span> Standard-sized block used in construction

A concrete block, also known as a cinder block in North American English, breeze block in British English, concrete masonry unit (CMU), or by various other terms, is a standard-size rectangular block used in building construction. The use of blockwork allows structures to be built in the traditional masonry style with layers of staggered blocks.

This page is a list of construction topics.

<span class="mw-page-title-main">Efflorescence</span> Migration of a salt to the surface of a porous material

In chemistry, efflorescence is the migration of a salt to the surface of a porous material, where it forms a coating. The essential process involves the dissolving of an internally held salt in water, or occasionally in another solvent. The water, with the salt now held in solution, migrates to the surface, then evaporates, leaving a coating of the salt.

<span class="mw-page-title-main">Waterproofing</span> Process of making an object or structure waterproof or water-resistant

Waterproofing is the process of making an object or structure waterproof or water-resistant so that it remains relatively unaffected by water or resisting the ingress of water under specified conditions. Such items may be used in wet environments or underwater to specified depths.

<span class="mw-page-title-main">Plasterwork</span> Construction or ornamentation done in plaster or a similar material

Plasterwork is construction or ornamentation done with plaster, such as a layer of plaster on an interior or exterior wall structure, or plaster decorative moldings on ceilings or walls. This is also sometimes called pargeting. The process of creating plasterwork, called plastering or rendering, has been used in building construction for centuries. For the art history of three-dimensional plaster, see stucco.

<span class="mw-page-title-main">Exterior insulation finishing system</span> Non-load bearing building cladding

Exterior insulation and finish system (EIFS) is a general class of non-load bearing building cladding systems that provides exterior walls with an insulated, water-resistant, finished surface in an integrated composite material system.

<span class="mw-page-title-main">Vapor barrier</span> Damp proofing material in sheet form

A vapor barrier is any material used for damp proofing, typically a plastic or foil sheet, that resists diffusion of moisture through the wall, floor, ceiling, or roof assemblies of buildings and of packaging to prevent interstitial condensation. Technically, many of these materials are only vapor retarders as they have varying degrees of permeability.

<span class="mw-page-title-main">Fireproofing</span> Rendering something (structures, materials, etc.) resistant to fire, or incombustible

Fireproofing is rendering something resistant to fire, or incombustible; or material for use in making anything fire-proof. It is a passive fire protection measure. "Fireproof" or "fireproofing" can be used as a noun, verb or adjective; it may be hyphenated ("fire-proof").

<span class="mw-page-title-main">Lime mortar</span> Building material

Lime mortar or torching is a masonry mortar composed of lime and an aggregate such as sand, mixed with water. It is one of the oldest known types of mortar, used in ancient Rome and Greece, when it largely replaced the clay and gypsum mortars common to ancient Egyptian construction.

<span class="mw-page-title-main">Cavity wall</span> Type of wall with a hollow center

A cavity wall is a type of wall that has a hollow center. They can be described as consisting of two "skins" separated by a hollow space (cavity). The skins typically are masonry, such as brick or cinder block. Masonry is an absorbent material that can slowly draw rainwater or even humidity into the wall. One function of the cavity is to drain water through weep holes at the base of the wall system or above windows. The weep holes allow wind to create an air stream through the cavity that exports evaporated water from the cavity to the outside. Usually, weep holes are created by separating several vertical joints approximately two meters apart at the base of each story. Weep holes are also placed above windows to prevent dry rot of wooden window frames. A cavity wall with masonry as both inner and outer skins is more commonly referred to as a double wythe masonry wall.

<span class="mw-page-title-main">Damp (structural)</span> Presence of unwanted moisture in the structure of a building

Structural dampness is the presence of unwanted moisture in the structure of a building, either the result of intrusion from outside or condensation from within the structure. A high proportion of damp problems in buildings are caused by ambient climate dependent factors of condensation and rain penetration. Capillary penetration of fluid from the ground up through concrete or masonry is known as "rising damp" and is governed by the shape and porosity of the construction materials through which this evaporation-limited capillary penetration takes place. Structural damp, regardless of the mechanisms through which it takes place, is exacerbated by higher levels of humidity.

Basement waterproofing involves techniques and materials used to prevent water from penetrating the basement of a house or a building. Waterproofing a basement that is below ground level can require the application of sealant materials, the installation of drains and sump pumps, and more.

<span class="mw-page-title-main">Building insulation material</span>

Building insulation materials are the building materials that form the thermal envelope of a building or otherwise reduce heat transfer.

Concrete sealers are applied to concrete to protect it from surface damage, corrosion, and staining. They either block the pores in the concrete to reduce absorption of water and salts or form an impermeable layer which prevents such materials from passing.

<span class="mw-page-title-main">Truscon Laboratories</span>

Truscon Laboratories was a research and development chemical laboratory of the Trussed Concrete Steel Company ("Truscon") of Detroit, Michigan. It made waterproofing liquid chemical products that went into or on cement and plaster. The products goals were to provide damp-proofing and waterproofing finishing for concrete and Truscon steel to guard against disintegrating action of water and air.

References

  1. 1 2 Greenlaw, Bruce. "Moisture-Proofing New Basements", Foundations and concrete work. Newtown, Connecticut: Taunton Press, 2003. 93. Print.
  2. "Rising Damp | Rising Damp Treatment". Thornhill damp proofing. 2019-04-12. Retrieved 2021-06-30.
  3. "Damp Proofing | Providing The Best Damp Treatments". Timberwise. 2015-08-06. Retrieved 2018-09-17.
  4. 1 2 3 4 5 Punmia, B. C., A. K. Jain, and Arun Kumar Jain. Building construction. 10th ed. New Delhi: Laxmi Pub., 2008. 631. Print.
  5. "Damp-proof membrane (dpm, DPM)" def. 1. Gorse, Christopher A., and David Johnston. A dictionary of construction, surveying, and civil engineering. Oxford: Oxford University Press, 2012. 104. Print.
  6. P.C. Varghese (2005). Building Materials. PHI Learning Pvt. Ltd. p. 230. ISBN   81-203-2848-5.
  7. Curtin, William George. Structural masonry designers' manual. 3rd ed. revised Oxford: Blackwell Science, 2008. 314. Print.
  8. "The Role of Preformed Cavity Trays in Construction by CODA Products Ltd - Happy UK Magazine". 2023-11-11. Retrieved 2023-11-18.
  9. Greenlaw, Bruce. "Moisture-Proofing New Basements", Foundations and concrete work. Newtown, Connecticut: Taunton Press, 2003. 93-101. Print.
  10. Society of the Protection of Ancient Buildings. "Technical Q&A 20: Rising Damp". Archived from the original on 2014-02-28. Retrieved 16 July 2013.
  11. ZFN (2021-02-19). "How To Treat Damp Walls Internally". ZFN. Retrieved 2021-03-30.

Commons-logo.svg Media related to Damp proofing at Wikimedia Commons