The structural moisture is the presence of unwanted moisture in the building structure, either the outward intrusion or condensation from within the structure.
The high proportion of moist problems in buildings is caused by condensation, rain penetration or damp rising.
Video Damp (structural)
Symptoms
Humidity tends to cause secondary damage to buildings. Unwanted humidity allows the growth of various fungi in wood, causing health problems to decay or mold and can eventually lead to sick building syndrome. Plaster and paint worsen and wallpaper slack. Stains, from water, salt and from mushrooms, surface mar. The highest concentration of air molds is found in buildings where significant mold infestations have occurred, usually as a result of severe water intrusion or flood damage. Fungi can grow on almost any surface and occur where there is a lot of water vapor from structural problems such as leaky roofs or high humidity levels. Concentrations of airborne fungi have the potential to be inhaled and can have health effects.
Externally, mortars may collapse and salt stains may appear on the walls. Steel and iron rusting fasteners. It can also lead to poor indoor air quality and respiratory illness in the occupants. In extreme cases, mortar or plaster may fall from the affected wall.
Maps Damp (structural)
Health effects of structural moisture
Health problems surrounding mold include infections, allergies or immunological diseases, and nonallergic diseases. Asthma is also triggered by the sensitization of dust mites derived from the wet and wet areas of a structure. Another health effect associated with structural humidity is the presence of bacteria in the indoor environment. Bacteria need water to grow and multiply and certain species can cause disease in humans, so the intrusion of water into the indoor environment can put occupant health at risk from bacterial infections. Water removal and drying of wet building materials within 2 days are likely to prevent the growth of fungi and bacteria, thereby reducing the vulnerability of residents to disease.
A Visual Guide to Damp, Mold and Indoor Pollution. state that:
"Excess moisture - in virtually any material in the room - for microbial growth such as molds, fungi and bacteria, which then emit spores, cells, fragments and volatile organic compounds into the indoor air.In addition, the moisture starts chemistry and/or biological degradation of the material, which also causes indoor air pollution.Exposure of microbial contaminants is clinically linked to respiratory symptoms, allergies, asthma and immunological reactions.Solutions have therefore been suggested to be a strong and consistent indicator of risk for asthma and respiratory symptoms such as cough and wheezing. "
Identify
Various instruments and techniques can be used to investigate the presence of moisture in building materials. When used properly, they can provide valuable assistance for investigation. The competence and experience of the person doing the wet investigation is often more important than the kit he is carrying. A qualified experience and surveyor is the difference between a correct and false diagnosis of humidity. For example, it is sometimes found that condensation is incorrectly diagnosed as another form of moisture that results in the wrong form of prescribed treatment. Hired building surveyors are usually experienced in identifying moisture issues, but their reports often indicate that moisture problems are studied by wet and wood surveyor specialists with CSRT qualifications.
The process for diagnosing moisture improvements in buildings is defined in the BRE Digest 245.
Prevention and treatment
Most forms of moisture can be prevented by prudent building design and careful construction. In the UK, well-built modern homes include wet inspection in the form of a wet-proof synthetic course (DPC), about 15 cm above ground level, to act as a barrier where water can not pass. Low-porosity slate or "brick engineering" is often used for some of the first programs above ground level, and this can help minimize problems.
There are many approaches to moisture maintenance in existing buildings. The key to choosing the right treatment is the correct diagnosis of the types of moisture that affect the building. The details of possible treatments for certain types of moisture are included in the sections below.
The cause of moisture must first be eliminated, by providing better drainage or fixing leaking pipes. BRE Digest 245 describes several methods for treating increased humidity, including the use of soil channels and the physical and chemical DPC insertion. Then, any affected plaster or mortar should be disposed of, and the walls are treated, before replacing the plaster and repainting.
Humidity
Humidity occurs in indoor environments because it builds related causes. Porous walls, damp rises, and leakage in buildings are the deciding factor for structural humidity due to high humidity levels. Construction of the building can also cause unwanted humidity and humidity in the indoor environment. Wet materials, such as wood kept outside unprotected homes before construction, can cause increased indoor humidity until up to the second year of occupancy within the building. Most often in residence, increased relative humidity is generated by poor drainage systems. This causes moisture in substructures such as crawling spaces and dungeons. Humidity produces evaporation in which water vapor is transmitted to the building's interior. Water vapor can enter the building through the supply air passages in sheet building and is circulated by warm forced air. Water vapor can also enter buildings through back air channels leaking in homes by crawling.
Human occupation adds a large amount of moisture to the indoor environment. Basic personal activities such as breathing and sweat add moisture to indoor space. Cooking and bathing increase the level of humidity in an indoor environment, which directly affects the structural moisture of the house. Aspects of the house can also increase the humidity of space. Items such as aquariums, indoor pools, hot tubs, and even indoor plants add to the humidity of the indoor space. All of these attributes can increase the recommended home moisture outside thirty to fifty percent.
Humidity levels in the indoor environment need to be calculated based on the season and temperature. If the humidity level does not correspond to the time of year and temperature during the season, mold infestation and damage to the building will occur due to moisture. Acceptable humidity levels in indoor space range from twenty to sixty percent throughout the year. However, rates of less than twenty percent in winter and higher levels of sixty percent in the summer are considered unacceptable for indoor air quality. Structural humidity may occur as well as an increased health risk associated with moisture damage.
Prevention and treatment
There are strategies to prevent water infiltration due to moisture into the structure, as well as ways to treat human living practices about moisture. Steam retarder is a material that can be used to withstand uncontrolled airflow and moisture to indoor space. The steam retarder is used to lower the rate and amount of water vapor diffusion through ceilings, walls, and floors caused by moisture. Made of a thin, flexible material and upholstery can be fitted with a shovel or brush. Utilizing a steam retarder in a building prevents structural humidity from occurring or continuing if it already exists. Strategies to reduce the humidity level in the indoor environment is to change the activity of occupants and mechanics indoors. The kitchen and bathroom should have its own ventilation. In addition, the washing machine should be thrown outdoors. Both of these are important to reduce indoor humidity due to the humidity caused by activities that occur in the indoor spaces. Humidity sources, such as hot springs or indoor pools, should be covered with airtight caps when not in use, so humidity levels remain low in indoor environments.
Condensation
Condensation comes from water vapor in the building. Common sources may include cooking, bathing, dishwashing, etc. Humidity in the air condenses on a cold surface, sometimes inside a wall called interstitial condensation. Buildings with poorly insulated walls are particularly vulnerable to this problem. Often cause similar damage to the damp in the building and often appear in the same place. This is because it occurs in "dead air" pockets that accumulate at both horizontal and vertical angles (ie from circulating air patterns).
Humidity condenses on the inside of the building due to the specific interaction between the roof and the wall. Leaks are most common in flat-roofed buildings. Certain building materials and mechanisms can be used to prevent condensation in this area, thereby reducing structural moisture and potential mold infestations. In many cases, insulation between roof and wall is compressed, causing a decrease in thermal resistance. Due to the lack of heat resistance, there is condensation, which causes water damage in the indoor environment. In most cases where moisture is not handled fast enough, mold and mold develops. Another problem is the wind that goes into the gap where the roof and wall cut reduces the efficiency of insulation. This results in condensation and risk for mold growth.
In the UK, the condensation problem is very common between October and March - so far this period is often referred to as the "season of condensation."
Condensation identification
If it is suspected that the problem is condensation, then the room should be closed with the dehumidifier left running for the suggested time and then further instrument tests are made. If the moisture is lost, condensation is very likely to be a problem.
Or the Humiditect card or datalogger (measuring air humidity, air temperature, and surface temperature) can be used as a tool to diagnose condensation problems.
Treatment
Common solutions for condensation include improving background heat and ventilation, improving cold surface insulation and reducing moisture formation (eg by avoiding indoor clothes drying).
Raindrop
Rain Penetration (also known as "penetrating moist" ()) is a common form of moisture in buildings. This can happen through walls, roofs, or through openings (eg express windows).
Water will often penetrate the outer envelope of the building and appear inside. Common defects include:
- Roof damage such as blackboards or broken, cracked, or missing tiles.
- Damage to walls or masonry such as missing or cracked bookmarks. Porous brick or stone.
- Lost or broken mastic around windows and doors.
- The cried hole is blocked.
- Tray missing or damaged in the cavity wall.
Wall
Rain penetration is most often associated with a single skin wall, but can also occur through the cavity walls - eg. by tracking cross-bound walls.
Primary Cause
The main cause of penetration of rain through walls is defects in masonry - for example:
- Porous rock (ie brick under pressure, porous rock, or porous mortar)
- Crack
- Disabled pointer
- Unallocated and matching joints,
- Defects around doors and windows
- Hole in the wall - e.g. where cable or pipe stands out
- Rendering is broken
Exacerbator from Rain penetration
Where the wall suffers one or more of the main causes of rain penetration listed above, the problem may be exacerbated by one of the following exacerbators of rain penetration:
- Damaged rainwater items
- Growth of mosses in tile (causing blockage of rainwater items)
- Broken or missing window frames (causing high concentrations of rainwater to survive on the wall beneath the window)
- Non-breathing coatings such as acrylic pairs of paint - especially when applied to a poorly prepared stone substrate
- Location/wall aspect - e.g. wall facing prevailing winds are more susceptible to rainfall penetration problems (see BS8104)
- Extreme rainfall periods (eg winter 2013/2014) - walls that are usually thick enough to prevent rain from reaching the inside of the face can be overwhelmed during periods of heavy and continuous rain
Modifications to buildings involving impermeable materials can also worsen the rainfall penetration symptoms by trapping moisture. This can be a special problem with the installation of external wall insulation (EWI) retrofit.
Increased humid
Rising moist is a general term for slow upward water movement at the bottom of walls and other supported structures of soil by capillary action. Although a wet rise up to 5 meters high has been observed the height of increase is usually much lower and rarely above 1.5 m. Rising moist has been a widely observed phenomenon for at least two hundred years. There is also strong evidence to suggest that it was a problem understood by the Romans and the Ancient Greeks. Just like most other moist forms, the increase in moisture is often misdiagnosed in buildings. Many mistakenly define wall stains as wet examples that go up by misinterpreting visual evidence from walls and moisture meter readings.
Simply, the moist increase occurs when groundwater moves upward through porous construction materials such as bricks, sandstone, or mortar, just as oil moves upward through the light axis. The effect can be easily seen by simply placing a piece of porous brick, stone, or mortar in a shallow tray of water and observing how water is absorbed into the porous material and transported above the water line.
Rising moisture can be identified by "tidal mark" characteristics at the bottom of the affected wall. These pairs of marks are caused by the soluble salts (especially nitrate and chloride) contained in ground water. Due to the evaporation effect, these salts accumulate at the "peak" of the rising moisture.
Increased humidity - Historical context
The problem of increasing humidity has been a concern since ancient times. The Roman architect Vitruvius refers to the matter of moisture rising to the wall and advising on how to build buildings to avoid problems.
The damp rising is widely referred to in Victorian literature and the Public Health Act of 1875 introduces the requirements for wet-proof courses on walls to prevent rising moisture. An entry in the British Medical Journal of 1872 describes the following rising moisture phenomena:
"Even if the rising moisture is captured by what is technically called wet-proof only, it will often be found that this was built on the wall too close to the ground line, resulting in heavy rain pounding the ground and splashing over it, due to the time of rolling on the surface of the ground is also high, and the wet track is soon gone from sight.Every effort has been made to repair this crime from porous bricks with the replacement of a hard blue brick from Staffordshire, it may often be noted that wet only attacks, such as sailors, crossed joints mortars and fence inner walls like tartan boxes. "
In July 1860 it was reported in The Engineer that In the Salford Hundred Quarter Sessions on Monday, it was officially declared by the Assize Court Committee that the completed foundation has been closed with asphalte by Messrs. Co., from Liverpool, which ensures that it will be damp. "
Architects and social reformers, Thomas Worthington, described the rising damp in his essay in 1892, "The Poor Residence: And Weekly Wage Income in and around the City":
"It should be remembered that wet walls absorb more heat than dry ones and that they are often the causative agent of rheumatism, kidney disease and colds.The rising moisture of the soil can be prevented in the simplest way.6 Six inches of good Portland concrete cement should cover the whole the location of the dwelling, and the concrete that is never less than nine inches thick should underlie all the walls A wet course should break the entire foundation of the superstructure.This precaution can consist of a thick layer of thick boards arrayed in cement, or blocks of potholes patent or three quarters of an inch of the best bitumen. "
In his publication, "Hels to Health" (1885), finance and philanthropist Henry Burdett, describes the need for an effective wet-resistance course to protect against increased moisture:
"After that be careful that air and humidity will not have a chance to climb into the house from the ground beneath the floor, we now have to turn our attention to the wall, which is equally necessary to protect from rising moisture. a brick or stone wall on the ground that is able to withstand the humidity, it will inevitably happen that unless you take the means to stop its progress, water vapor will rise to the wall in compliance with the law of capillary tugs.The way to prevent this is to insert above ground level but below the floor level, either a deliberately prepared vitrified stoneware course, or two layers of plates placed on cement, or some similarly effective fireproof material, the intervention between two brick beam programs will prevent further progress from moisture (see figure 1). "
Henry Burdett is deeply concerned about the quality building in British Victoria, and he warns prospective home buyers to inspect homes for the presence of wet-resistant courses and to ensure that it is an effective type.
"Regarding wet-proof course, however, it is possible to know what to look for, and where to look for, to look for certainty whether or not there.Check carefully the joints of the brick between the ground and the floor level below A wet vitrified stoneware would certainly be striking from the perforation, and the color difference between it and the brick.Aphalte or whiteboard or cement alone would all appear, the latter two like mortars about three or four times the usual thickness.Favorite material with speculators speculating is a palpable or paved feel, a presence that can generally be detected by the parts it projects from the wall. Its wealth is, for all practical purposes, useless, and without consideration should any Local Authority prohibit its use. "
As an example of poor workmanship leading to an ineffective damp proof course, Burdett cites the following example:
"The wet course shown in Figure 2, sketched from a house in Willesden, is a remarkable illustration of how to keep moist from rising.This consists of just one of the usual roof slates placed in a mortar, with a space of at least an inch between each slate and the next. "
Skepticism
Rising wet is a phenomenon that is fully predicted by the laws of physics, has been researched on a world scale, and has been documented since Roman times. Nevertheless, a small number of people have expressed the view that a moist rise is a myth and that, in fact, it is impossible for moisture to rise from the ground into the wall structure through the pores in the rock. A former chairman of the Royal Institution of Chartered Surveyors (RICS) arm, Stephen Boniface, says that 'really damp ride' is a myth and the damp chemically moistured course (DPC) is a 'waste of money'. But he recently clarified this statement on a comment post made on the Property Survey website, "Although I am often quoted as saying" rising damp is myth "the only time I ever said that sentence (or similar) Once upon a time when giving a paper at a conference and then using a breath intake as a gesture for later developing further arguments and exploring the problem of damp.In other words, I use provocative phrases (usually succeed).I then went on to state that while I received a moist rise (as a term often used by the public and professionals) may be very rare.I have at other times referred to the myth of increasing humidity and explaining what I understand without actually claiming myself that it is a complete myth. " >
Konrad Fisher's article "The Fraud of Rising Damp" shows that the historic town hall in Bamberg stands on the river Regnitz and the bridge remains dry with no chemical, mechanical, or damp electronics. However, supporters of the moist rise indicate that not all walls are capable of supporting a moist rise, so just observing that a moist increase does occur on a particular wall does not deny its presence on another wall.
In 1997, the damaged housing team at the Lewisham Board in South London was so convinced that the rising damp was a myth that they were offering a prize of £ 50 to anyone who could show them the original case. Manager Mike Parrett said, "The essence of the reward is to convince our tenants that the rising damp is a myth." Lewisham never found the original case that wet up and never paid a prize of £ 50.
Water intrusion into the indoor environment can be caused by a cause other than a wet rise. The penetration of moisture has become a sustainable problem for shelter because evaporation takes place on the edge of a humid area, resulting in a "tide mark" due to salt deposition. The "plug" marks are generally distinguished as features of a moist rising. However, even after water intrusion has been treated, this salt accumulation still persists. This suggests that the moist increase is not always the cause of water penetration.
The Building Research Establishment (BRE) in its review concludes that increasing moisture is a real problem.
How the moist increase occurred
According to Jurin's law, the maximum rise is inversely proportional to the capillary radius. Taking the typical pore radius for a 1 Ã,Âμm building material, Jurin's Law will give a maximum rise of about 15 m, however, due to the evaporation effect, in practice the increase will be much lower.
The physical model of the increased moisture was developed by Christopher Hall and William D Hoff in their paper "Rising damp: the dynamics of capillary rise on the wall". This analysis is based on properties of experimental porous building materials that have been proven experimentally and evaporation physics from the surface of the building. Hall and Hoff suggest that the model can be used to predict the moist height will rise on the wall. The height of the increase depends on the thickness of the wall, the flexibility of the wall structure and the rate of evaporation. Further work has been confirmed experimentally the importance of mortar properties in determining the moist height will rise on the wall. BRE Digest 245 lists several factors that may affect the height of the increase including the evaporation rate of the walls, the pore size of the masonry, the salt content of the material and soil, ground water and saturation levels, and the use of heating in the property. The effect of seasonal variation in evaporation rates at elevated moisture levels has been described comprehensively.
A review of data and publications commissioned by the Property Maintenance Association and conducted by the University of Portsmouth concluded that "Wet Rising is an old-fashioned and ubiquitous problem." He also notes that "The record of observations and descriptions on the date of this phenomenon goes back to the early days, which was identified as a public health problem in the second half of the 19th century." This review looks at data and studies on the rising humidity of a number of countries including Britain, Portugal, Germany, Denmark, the Netherlands, Greece, Australia and Malaysia.
Diagnosis of increased damp
The first step in assessing humidity is to check the presence of water. Removing water with good drainage will remove any form of moisture. Once done, and the remnants of moisture, the next step is to look for the existence of a wet-proof course. If a wet-resistant course is present, it will likely function, as the material from which moisture proof programs are produced tends to have longevity. However, it must be admitted that there are cases where the existing damp proof program fails for one reason or another.
One commonly used indicator to determine whether the moisture source increases wet (not another form of moisture) is to look for the presence of salt - especially the "salt band" or "tide" tale at the top of the moist rise. This is not a reliable method because salt and moisture can get into the fabric of the walls in other ways - eg. sea ​​sand or pebbles used in the construction of the wall.
If no wet-proof course and suspected moist rise (tidal marks, moisture confined to the bottom of the wall etc....) then a number of diagnostic techniques can be used to determine the source of moisture. BRE Digest 245 states that the most satisfactory approach is to obtain mortar samples in affected walls using a drill and then analyze these samples to determine their moisture and salt content to assist in providing appropriate building repair solutions. The fact that this technique damages the finished wall often makes it unacceptable to the homeowner. For this reason an electric moisture meter is often used during surveys to improve humidity. This instrument can not accurately measure the moisture content of stones, as they are developed for use on wood, but the achieved reading patterns can provide useful indicators of moisture sources.
Increased moist treatment
In many cases, moisture is caused by "bridging" of wet-moist courses that otherwise work effectively. For example, a flower bed next to the affected wall can lead to soil accumulating on the wall above the DPC level. In this example, water vapor from the soil will be able to enter through the wall from the ground. Such damp problems can be fixed by simply lowering the interest to levels below the DPC.
Where increased damp problems are caused by lack of wet-proof courses (common in buildings over about 100 years) or with failing wet-proof courses (relatively rare) there are various possible solutions available. These include:
- Physical damp replacement is of course evidence
- Injection of moist or moist chemically only (DPC Injection)
- Anti-humid stem
- Other porous/vaporized tubes
- Land drainage
- Electro-osmotic system
Physical humid replacement of course proof
A physical damp proof course made of plastic can be plugged into existing buildings by cutting short pieces of the mortar course, and installing a short section of the damp course material. This method can provide a very effective barrier to improve moisture, but it is not widely used because it requires experienced contractors to carry out if structural movements should be avoided and require more time to install than other types of improved wet care. The cost is also several times higher than other types of wet treatments.
Injection of moist liquid or moist humid chemistry (DPC Injection)
Injection of fluids or creams into bricks or mortar is the most common method for treating moisture.
Liquid injection products were introduced in the 1950s and are usually installed using a funnel (gravity feed method) or a pressurized injection pump. The effectiveness of the product of moist injection of liquid injection depends on the type of formulation and skill of the installer. In practice, injection time tends to be lower than that required to provide a moisture-proof program of optimum effectiveness. A paper published in the Building and Environment in 1990 made the following calculations about the time of injection:
These calculations for various bricks and one stone show that when high pressure injection is used the injection time is not possible less than five minutes per hole and can exceed 20 minutes per hole even for relative permeable and porous materials. for a low pressure repellent infusion ranging from 8 hours to 44 hours. "
In recent years, patented anti-wet creams patents EP 1106590 have taken over from a liquid product due to increased ease of application. Like liquid products, it is based on silane/siloxan active ingredients that coat the mortar pores to ward off moisture.
The effectiveness of moist and cream based treatments varies greatly between product variations due to variations in product formulations. Independent certification tests such as British Board of Agreement (BBA) certificates are available for some products, indicating that they meet the minimum requirements for product performance.
Anti-humid stem
The moist test rods use the same active ingredients as those found in moist or cream-based treatments, but are contained in solid rods. They are generally considered easier to use than any other type of moisture treatment that increases because of its mounting method just to insert them into the correct size holes drilled into the mortar bed. Anti-wetting rods are available with BBA approval.
The rod is placed into the hole drilled in the mortar and the active ingredients spread along the mortar line prior to preservation to form a wet-proof course.
An anti-wetting rod is usually available in 180mm sizes suitable for insertion into a 9-inch thick wall. To care for a thick brick wall (4.5 inches), the stem is only cut in half.
The benefits of moist-wet stems compared to moisture-resistant creams and liquids is that it is possible to ensure a consistent dose of active ingredients to every hole drilled in mortar courses - ie it is not possible to fill the holes.
Porous tube
Porous tube is installed along the mortar road. In theory it encourages evaporation and reduces the appearance of moisture. Independent certification tests are available for this type of product and tests conducted by Building Research Establishment show that they are effective in controlling the increase in moisture.
"Porous ceramic tube is a preliminary technique to produce an improved moist combat method, in the 1920s it was marketed by the British Knapen.The tests are written in the Annual Building Annual Report 1930:" There are tests to determine the effect on the level evaporation of moisture from the porous clay tube tends to be arranged in specimens of brick and natural stone, laboratory experiments and field tests have been carried out The results show increased moisture evaporation results from the use of these tubes.. '"
Land drain
It has been suggested that improving drainage around walls affected by rising moisture can help reduce elevation by reducing the amount of water available to be absorbed into the wall capillaries. Usually the trenches will be dug up around the affected wall where a porous pipe will be laid. The moat will then be refilled with porous materials such as single-sized aggregates, forming a French channel.
Such a system would obviously have a practical disadvantage as it is only suitable for outside wall maintenance and would be impractical where other buildings are near or where the building has a shallow footing. Although the theory of reducing moisture increases by reducing the amount of moisture in the underlying soil will seem like a sound, there is little data to suggest that it is effective in practice. Indeed, G and I Massari stated in the ICCROM publication "Old and New Wet Buildings" that small effects were observed with "open excavations" and no effects were observed with "closed trenches."
Electrical osmotic system
These efforts to control the moist rise through the phenomenon of electro osmosis. While there is evidence to suggest that this system can be useful in moving salt on the walls there is little in the way of independent data to show effectiveness in treating moist improvements. The publication of BRE "Understanding Humidity" makes the following observations about the electro osmotic system for improved moist treatment:
"There are two types: active and passive, none of which are approved by a recognized laboratory." So far the larger number of systems is a passive type, where there is no external power source.There has always been a controversial problem.By theoretical basis, the mystery of how they can work, its effectiveness has not been proven in the laboratory and the field evidence is disappointing. "
The increased effectiveness of wet care
BRE Digest 245 indicates that with the exception of a physical DPC replacement, only treatment methods with third party accreditation (eg the UK Plantation Certificate Council) should be considered for improved moist treatment. It then states that the only current method that meets these requirements is a DPC injection (liquid or cream - even though wet-proof stems are already available with BBA approval) and that "this is the only method considered to be a suitable BRE in which DPC insertion physical impossible. "
The Royal Institute of Chartered Surveryors (RICS) of the "Remedying Damp" publication is more cautious about its reliance on third party accreditation, raising doubts over the validity of the test method used, on the grounds that trials are usually conducted using "specially constructed masonry panels - which does not fit in many ways for the walls found on real property, "and that" if DPC is proven to not to work in custom made masonry panels, it will be a more significant result. "The MOAT test No. 39 used by the British Board of AgrÃÆ'Â um um (BBA) in the UK was dismissed as "a pretty smart test idea but in the opinion of the author not really replicating the real wall." The author, Ralph Burkinshaw, has developed his own test method which he published under the heading, "Increased wet test at Camberwell Pier: The potential for high humidity rise in bricks and the effectiveness of modern chemical injections, wet creams flowing applications."
In April 2014, the UK Agricultural Council confirmed that it would consult producers and holders of BBA certificates with a view to updating the MOAT test No.39 in view of the fact that it was not designed to test moisturizing creams and this has become the most popular type of wet treatment. This supersedes the BBA's guidance notes which say the anti-wetting cream is different from liquid-based moisture-cleaning treatments in several ways:
1) The cream is applied at a much lower application level than is typical for fluid injection and is designed to spread through masonry by diffusion without the help of pressure injection. Because of the different types of mortar and water content, it is necessary to test these materials under a wider range of conditions. Research conducted by BBA shows that the performance of the cream is different from the various test conditions, with not all products performing well under all test conditions.
2) The number of active ingredients sent per linear meter varies greatly between cream formulations. The injection system is usually injected at an application level of about 100g of active ingredient per meter of linear wall thickness of 275 mm (9 inches). However, since the strength of cream formulations used in the UK can vary greatly, the amount applied from active ingredients sent varies from 22g to 107g per linear meter depending on the strength of the product. Because there is limited historical data about chemical cream endurance with low levels of active ingredients, it is difficult to draw conclusions on their life expectancy compared to high strength creams that have the same active ingredient levels as the injected system.
In his book, Dampness in Buildings, Alan Oliver refers to research undertaken in Belgium on the effectiveness of various types of improved wet care:
"In Belgium, at the Center for Scientific and Technical Construction (CTSC, 1985), research was undertaken on the effectiveness of major retrofit DPCs found in Europe.In general it was found that DPC physically performed best, followed by various chemical DPCs, with electro osmosis and atmospheric syphons being the most effective. "
Replastering
Replastering is often done as part of improved wet care. Where plaster has been severely damaged by soil salt there is little argument about the need for a replaster. But there is a great debate about:
- The required replastering rate
- Use of hard sand: cement becomes a replaster as part of an improved wet treatment
BS6576: 2005 states that the function of new plaster is to prevent possible hygroscopic salts in the wall from migrating to its surface while still allowing the walls to dry. in the RICS "Remedying Damp" publication, Ralph Burkinshaw claiming that "plaster really exists for two reasons." He accepts the need for replastering when large amounts of ground salt have been built in existing plaster, but he then goes on to say that replastering is often done to make up for the DPC chemistry that is unreliable.He also suggests that moisturizers have an incentive to do replastering more than necessary because it allows them to complete the job without having to wait for the wall to dry out, so paying is faster.
Although cement-sand rendering is usually installed as part of an increasingly effective moist treatment that is very effective for holding back wet salts and soil, they have a number of disadvantages. These include incompatibility with soft bricks and mortar found in old buildings and lack of insulation properties compared with more traditional plaster, thereby increasing the risk of condensation. Replastering is also one of the most expensive parts of improved wet care.
Porous renders for the German WTA 2-2-91 specification can be used as an alternative to solid cement-sand rendering. It has a minimum porosity of 40% of the total volume. Salt crystallizes in these pores rather than on the surface of the plaster, avoiding decorative damage. Such plasters offer a better solution than solid cement-rendement when used on salt-contaminated walls because their porous nature gives them insulating properties, which results in a warmer surface temperature and makes the condensation problem less likely. However, when used on heavy salt contaminated walls they may need to be replaced frequently because they lose effectiveness after all the pores have become filled with crystallized salts. The "Renovation Mortars" described in EN998-1: 2003 are described as designed for use on "masonry walls containing dissolved salts." The performance requirements for this type of mortar are based on the German WTA specification 2-2-91 but without the requirement for a minimum porosity of 40% of the total volume.
Recently, systems have become available that allow plasterboard or insulation boards to be used for replaster walls influenced by increased humidity. Once the existing plaster is hacked from the wall, a salt and moisturizing cream is applied to the wall. The plaster is then applied to the wall using a salt/moisture-proof adhesive. Such systems have the advantage that they can be directly decorated, rather than having to wait several days or weeks (as is the case with standard plaster). They also provide a warmer surface that is less susceptible to condensation than would be the case with standard sand: cement rendering.
Replastering may not be necessary if salt contamination is not severe. BS6576: 2005 states that "If the plaster appears to be in sound condition, the area of ​​plaster to be removed can be minimized by delaying any decision for the replaster until the drying period is complete." Avoiding the need for a replaster in this way can reduce the disruption and clutter and has the advantage of allowing gypsum-based lime original or to be maintained. However, the disadvantages of any wet-proof repair course will be clearer if the walls are not covered with waterproof rendering. For this reason, it is important to check the BBA certificate from a humid-checking system to ensure that it applies to use where replastering is not performed. Redecoration
The best practice is to postpone replastering and redecoration as long as possible after increased moist treatment, but this obviously creates inconvenience for the occupants of affected buildings. BRE Digest 245 states that "While the wall should be allowed to dry for as long as possible, replastering may follow, providing a porous decoration selected.It is usually a matt emulsion and a water-based paint, both of which will allow the wall to breathe.The application of gloss and vinyl paint or wallpaper should be delayed for at least a year. "
Plasterboard-based replastering systems have the advantage that direct redecoration is possible regardless of which decorative finish is selected.
Due to the fact that increased moisture often coincides with other damp forms such as condensation, the use of fungus-resistant emulsion paints is often recommended.
References
External links
- Institute of Surveyor and Engineer Specialists (ISSE - UK) A UK-based international agency specializing in structural moisture, committed to creating & amp; raising standards and representing the highest standards in the industry
- Howell, Jeff. Increasing wet myths
- Property Maintenance Association. British trade association for professionals who are damp resistant
- Waite, Richard (2009-06-26). Increased humidity is a myth, says head [Stephen Boniface, former Head of Royal Chartered Surveyor Institute].
- Wet World Health Organization and printouts: health risks, prevention and corrective actions
- Rising wet solutions
- Dawson, Adrian. What improves moisture?
Source of the article : Wikipedia
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