Treatment of dry spoilage refers to techniques used to remove dry fungus and reduce the damage done by fungi to man-made wood structures.
Dry rot ( Serpula lacrymans ) is considered difficult to remove, requiring drastic action. Repeated wood treatments and dampening companies usually recommend stripping of building materials beyond the real reach of infestation and the use of fungicides. A more holistic approach seeks to eradicate dry rot by controlling the local environment to reduce the level of wood moisture and increase ventilation to encourage drying.
The first priority when treating dry spoil is to find and remove moisture inside the building that causes the outbreak, and to promote drainage by taking steps, such as improving ventilation. The treatment approach differs after these steps are taken.
Video Dry rot treatment
Mycology of S. lacrymans
S. lacrymans is a form of brown decay, a group of fungi that digest cellulose and hemicellulose in wood. This particular species poses the greatest threat to the building as it can spread through materials that provide non-nutrients (eg, masons and plaster) for several meters until they find more wood to attack.
Dry rot is spread by spores present in most buildings. Minimum water content of wood for spore germination is 28-30% (lower than others), and relative humidity should be more than 95%. Spores are resistant to drought and may still be feasible to germinate when they are several years old.
If the condition is suitable, the spores will germinate producing microscopic yarn mushrooms called hyphae.
Table 1. Environmental conditions for growth of mycelium after germination
The average moisture content of modern softwood wood in dry buildings is generally in the range of 12-15%, and the heating system can reduce this to a much lower level. Therefore, there is no prospect of dry rot infestation that develops in buildings that have been designed, built, and maintained properly.
As soon as the environment begins to dry, the rotten will become inactive and eventually die. The length of time the fungus remained inactive under dry conditions seems to depend on temperature, with an estimated nine years at 7.5 Â ° C and one year at 22 Â ° C being quoted.
Most mushrooms will only develop in acidic conditions, but the dry rot will remain active under alkaline conditions. It gives the ability to grow through wet mortar, masonry, and plaster, infecting other areas of the building. Thick, performing strands known as rhizomorphs, are produced to cross the inert surface and penetrate the stone.
The fruit body (sporofor) can develop naturally or in response to poor humidity, temperature or fatigue fatigue conditions. Often this provoking stress is exposure to infestations. The fruit body will produce millions of brown rust spores.
One belief held about dry decay is that, once formed, it can survive by producing water by breaking wood if the original water source is removed. Laboratory experiments conducted in 1932 on wood samples in unventilated glass jars showed that significant amounts of water were produced. But this experiment does not mimic the "real world" environment of a building where the evaporation process and capillary action in the wood will remove moisture from the area faster than can be produced by the fungus.
Another misconception is that dry rot can transport water from a source within a considerable distance to dry wood areas so it can decay there. While the mycelium strands do nutrient solution around the fungus, it has been shown that the ability to transport water to "dry" dry wood is very limited.
Despite being a successful colonizer of buildings, for reasons not yet fully explained, S. lacrymans are rarely found growing in the wild. Specimens are occasionally found in the foothills of the Indian Himalayas, Mt. Shasta in California, and forests in Czechoslovakia.
Maps Dry rot treatment
Treatment Method
Introduction
The first step in any treatment is to make necessary improvements to building defects (overflowing drains, clogged bricks, lost whiteboards, etc.) that allow moisture entry. The treatment methods described below assume that dry rot has been positively identified, the degree of decomposition is fully confirmed, and that the building is now waterproof.
A number of methods of attacking dry rot have been developed which can be classified as follows:
- Orthodox - emphasis on the use of chemical fungicides
- Environment - emphasis on fungus control by controlling environmental conditions
- Thermal treatment - exploit the sensitivity of fungi to heat
- Biological treatments - use of competitor organisms
The last two methods are included for completeness as they are not currently widely used. The main purpose of this article is to compare orthodox and environmental approaches.
"Orthodox" Treatment for Dry Rot
The following description for the treatment of dry spoilage is typical of traditional methods:
- Cut out all the wood that shows decay, the presence of white mycelium, etc. and all the wood that seems to be heard within a meter's radius of the wood that looks the most rotten. Burn all such ingredients.
- Hack all casts/renders and remove any playbacks, panels, coatings and ceilings needed to fully track the growth above or through adjacent stone, concrete, or wooden walls.
- Clean with all-surface wire brush and any steel and pipe work within the area up to a radius of 1.5 meters from the furthest suspected infection level. Remove from building all the dust and debris that happens from work.
- Apply the fungicide to all pairs of rocks, concrete and ground surfaces at specified speeds. Apply two generous layers of fungicide to the entire surface of the wood up to a distance of 1.5 meters from the cut. (Let the first layer be absorbed before using the second layer)
- Use only completely preserved preservative wood instead.
- Replaster with zinc oxychloride (ZOC) plaster or, for unnecessary direplaster area, apply two layers of ZOC paint.
As can be seen from Phase 1 and 2, this involves the removal of a large number of building fabrics.
The desire to kill the mushroom strands in all materials adjacent to the affected wood has led to the practice of "wall irrigation" in stage 4. This requires saturating the rock with a water-soluble fungicide at a rate of about 10 liters/m 3 . Walls with a thickness of more than half brick need to be drilled with a distance of 230 millimeters (9.1 inches) to a depth of more than half the wall thickness. Walls of over Template: Convet460 thickness must be drilled from both sides. The fungicide is then injected into the hole, and the faces of the walls are sprayed.
Ensuring overall fungicide penetration across non-homogeneous wall structures is extremely difficult. "There is no practical way to ensure that all the rotting strands on the wall are killed."
A newer variation of wall irrigation practice is the "toxic box" in which the irrigation area is reduced to form a margin around the wall to contain fungi within the walls. Here there is nothing wrong and will eventually die of lack of food.
The application of fungicides to wood at stage 4 may be by brush, spray or injected under pressure into holes drilled into the wood. Preservatives based on organic solvents are used because these have better penetration into the wood rather than water-based solutions. Examples of suitable organic solvents include the following: (--- give an example to correct this page.). An alternative paste consisting of fungicides in an oil/water emulsion can be applied to wood.
In addition to the more conventional fungicides, boron-based fungicides can be supplied in a glass-like rod inserted into holes drilled into the wood. Boron is commonly available as a borax supplement, and as boric acid is commonly available from pharmacists or cockroach pesticides. Boron trunks can dissolve and if the wood becomes moist, the stems will gradually dissolve the preservative spread to the humid areas. Its use is appropriate for risky but unaffected areas. Surfactants (such as dish soap) are recommended in water-based preparations.
It has been reported that boron fungicide reacts with a wooden cellular structure in which boron is deposited, and it is this process that can vary to harden the dry rot, depending on the degree of wood degradation. However, structural members must be repaired by attending new wood after the fungal problem has been addressed. (Please confirm)
Preservative boron/glycol comprises an inorganic boron preservative that is dissolved in glycol to produce a paste. It is water soluble and will diffuse easily into the wet wood, even from the surface, and therefore offers better penetration than the more conventional fungicide products, where it is necessary to penetrate the wet wood.
The glycol solution has the advantage of being applicable on paint (please confirm).
Glycol and boron solutions are hydrophilic (loving water) and react with water in wood, making it unavailable for fungi. This is why the dry rot seems a bit stringy; The cells that grow in the drying period are smaller than the larger 'fat' cells that grow in spring, as can be seen in the tree circles used to know how old the tree is. This moist spring growth contains moisture consumed by mushrooms, other than that available from leaks, etc.
Water-based fungicides, being water-based, can be washed in time if the wood they use is kept wet. This is another reason why it is important to fix the leak and keep the wood dry and with a basic environment, and seal the wood and especially the final grain to prevent exposure to continuous hunger spores.
Fungicides to defeat chocolate decay include: baking soda, hydrogen peroxide, tea tree oil, boron solution, ethylene glycol or propylene glycol, vinegar, etc. Since dry rot fungi require acidic environments from pH --- to --- (please provide info), some of these fungicides work because they change the pH.
Recipes for homemade fungicide solutions and wooden and translucent epoxy have been reported on the web, in addition to commercially available products. (It would be greatly appreciated if you could improve the page by providing information about testing that demonstrates the efficacy of various treatments).
"Care" of the environment from dry spoil
The environmental approach can be defined as "exploitation of the environmental sensitivity of dry fungus for treatment".
Step-by-step procedures for using an environmental approach are:
- Promote drying from the affected area (eg by introducing forced ventilation from fans). Do not re-plaster, redecorate or cover the affected wood until completely dry.
- Identify, with the help of a structural engineer if required, any wood that requires replacement or strengthening due to loss of structural strength and carrying out this work. Store as many original fabrics as possible, especially in historic buildings.
- Isolation of wood from other materials that will take a long time to dry.
- Increase area ventilation if this is not enough, by introducing extra air bricks etc.
- Apply a routine inspection and maintenance schedule for the building to address future issues early on and/or install monitoring equipment.
An example of a situation in which Phase 3 refers is where solid rock walls have become wet because the sewer becomes clogged and rainwater is allowed to overflow into the wall for a period of time. Roof wood can rest on the wall. Even when the entry of water has been stopped and good ventilation is formed, it will take quite a long time for the walls to dry out. During this time, it is likely that there will be enough moisture to allow the growth of the fungus to continue. In this situation, it is necessary to isolate the wood from the pair with DPC material. Where the wooden ends are originally built into walls and are already weathered, these may be cut flat against the wall and connected by a beam hanger.
Or, the use of a paste and a boron rod will be justified in this regard. "Preservative treatment may be important in some situations if the fungus spread should be limited and critical wood should be protected while the structure dries."
The environmental approach emphasizes the need for continued monitoring to ensure that future building defects do not start a new outbreak of dry rot or reactivate the inactive. While in this simple little building can be achieved with routine maintenance inspections, a system is available that can monitor large buildings with readings from the humidity sensors monitored remotely by the computer.
Heat treatment
Other treatments have been tried that attempt to exploit the sensitivity of dry rot to heat. The use of blowlamp to kill dry rot by applying heat to the surface of the affected area is popular at one time. Of course, this causes a fire risk. Experiments show that the surface temperature of about 100Ã, ° C (212Ã,  ° F) should be maintained for up to five hours to produce temperatures that would kill the fungus in a thickness of 230 millimeters (9.1 inches). Wall.
In Denmark, procedures have been developed in which buildings, or affected parts, are placed and heated by hot air to kill dry rot. Temperature 40Ã, Â ° C (104Ã, Â ° F) was achieved in the carpentry and wooden center and maintained for twenty-four hours. However, the question can be asked why one should expend a large amount of energy to heat the entire building to high temperatures when all that is required to kill the rot is to dry it.
Microwave treatment systems have also been tried. More research will be needed before its effectiveness can be assessed.
Biological Control
Another more likely way to combat dry rot is the use of antagonistic organisms that reduce the ability of decaying fungi to colonize or degrade wood. The principle here is that when inside the building, the fungus is not in its natural environment and therefore natural competitors are unlikely to be present. It may, however, be possible to introduce these competitors into the building's environment to control dry decay.
Trichoderma fungus eliminates some of the woody structural carbohydrates needed for colonization and initiation of decay by wood-breaking fungi, and laboratory tests have demonstrated the ability of the Trichoderma fungus to kill S. lacrymans . Field trials have also investigated the ability of the Trichoderma fungus to prevent spoilage of electrical distribution piles, with mixed results.
This kind of biocontrol shows promise in the lab but is disappointing in the field, and more work needs to be done. Until now, the method of biological control has not yet become established.
There is also a problem with the potential allergies of Trichoderma which may limit its use in situations where human contact is possible.
Critics of the Orthodox Approach
Advocates of the environmental approach argue that the drastic action of the orthodox approach is in line with the popular misconception that dry rot is very difficult to eradicate. Instead, they will claim that it is not unusually tough and in fact very environmentally sensitive. Indeed, this environmental sensitivity may explain why it is so unsuccessful in the wild and can be used against it when encountered in buildings.
Perhaps the most criticized aspect of the orthodox approach is the practice of wall irrigation. As stated above, this involves inserting a water-based fungicide into the fabric of the building. But this is at a time when the main concern should be to dry the building.
Excessive water content on the wall will also cause a high risk of removal of salt out of the wall as it dries, thereby damaging the plaster and other solutions. Any salt stored on the surface of the wall may contain the fungicide used in the treatment, thus creating a potential health hazard.
The irrigation ability to kill all mushrooms inside the walls is also questionable, since the overall penetration of fungicides throughout the non-homogeneous walls is impossible, resulting in an uneven treatment. Case studies have been cited where dry rot has emerged from walls previously "sterilized" by irrigation - in one case, from walls that have been treated twice before.
It is questionable whether it is necessary to take steps to kill the fungus on the walls altogether because the mushroom strands do not cause damage to the stone itself. Instead, they just pass through the wall to look for more wood to attack. The "toxic box" technique, as described above, limits the irrigation to the perimeter of the wall. Even toxic box methods have been found for limited use. Doubts about the overall penetration of each fixed stone pairs, so it is questionable whether the complete barrier of the treated material can be formed around the edge of the wall.
The orthodox approach requires that all remaining wood in place be protected by the application of preservative fungicides. Like a mason, it is not easy to achieve full wood penetration. The penetration of surface spray and conventional pastes is severely disrupted by high levels of moisture in wood. The injection technique implements fluid inside the wood, but the distribution across the woodwork can be patchy. The use of boron/glycol preservatives does show an increase in penetration.
Another criticism of the orthodox approach is the number of removable building fabrics and the amount of repairs resulting from the repair and disruption of building use. Wall irrigation requires drilling a large number of holes into the masonry pairs.
Human Health Problems
One argument put forward by advocates of the environmental approach concerns the potential effects on human health from the large number of toxic chemicals used in orthodox treatments. The typical quote is: "chemical control methods cause extensive environmental degradation, pose a potential danger to wildlife and become a serious concern for public health agencies" and "..... many cases of illness including headache, respiratory problems and chest pain, to several names, have been linked to the use of these agents in buildings, and clinical evaluation tends to validate these concerns ".
However, others argue that no products used during the last twenty to thirty years have proved harmful to people when used correctly. In addition, there is a big difference between the use of wood preservatives and pesticides in other situations, especially agriculture, since wood preservatives are put into wood and are designed to live there for 50 years or more. Pesticides in agriculture, on the other hand, are released into the open environment.
Generally, the toxicity of fungicides used by industry has been reduced since 1991 with chemicals such as dieldrin, pentachlorophenol, and tributyltin oxide replaced by organo-boron esters, permethrin, and boron/glycol mixtures. One way to compare chemical toxicity is with LD 50 , which gives a relative dose to weight sufficient to kill 50% of the test population (usually rats).
Table 2. Relative toxicity of chemicals
Boron-based compounds are toxic to fungi, but their effect on mammals is minimal. However, a conventional wood preservative consists of an active ingredient and a solvent, and it is an organic solvent that seems to give more attention. No adverse effects arise due to limited exposure to hydrocarbon solvent vapors, but higher exposure levels may cause symptoms such as headache and nausea, which disappear as soon as the exposure stops.
Some evidence has been produced recently that workers exposed to high levels of solvent for several years can develop damage to the central nervous system, but studies have not been conclusive. This indicates that adequate ventilation in the treated area to dry product is all that is needed to prevent discomfort from the solvent.
Dr. David Watt, in an article published in the
Chemical treatments used for the control or eradication of fungal infections and/or insect infestations in such buildings and treatment residues do not pose a proven danger in the general population. Nevertheless, there is a potential real risk of such treatment and from the presence of residual treatment in treated premises for people suffering from chemical sensitivity... it is concluded that further investigation and evaluation are required from alternative chemical and non-chemical treatments of fungal and/or infestation infections insects in the building.
It should be noted that Watt treats the fungicides as a whole in his article: that is, he does not separate the effects of the active ingredients and the solvents.
Environmental Concerns
It has been stated that no care products used during the last twenty to thirty years have been shown to have caused damage to the environment when used correctly except in the case of isolated bats. However, at least in the UK, this is a major consideration, since bats are protected under the 1981 Wildlife and Rural Act, which states that injuring them or harassing their roost is a criminal offense.
Local damage to the environment will occur when pesticides are discharged to land or rivers by accident or disposal. Of course, there is always the possibility that any chemicals will not be used properly, either through ignorance or hatred, and advocates of the environmental approach will argue that there is no need to use large amounts of chemicals when there is a risk, but small.
Care Effectiveness
The experience of the companies involved in environmental control and research findings confirms that in most situations, dry rot can be fully controlled simply by changing the environment in which it grows. The Dry Rot Research Group at the University of Abertay has conducted laboratory tests on environmental control of dry decay in full-size models of floor/wall joints, windows, and roof/wall interchanges. The full results are published in a research report by Historic Scotland and conclusively show how dry rot growth can be controlled simply by varying the available moisture in the environment.
A case study of successful environmental control of dry decomposition in a large building is included as an annex in Scottish Historic "Technical Note" 24. Case studies are also quoted in Dr. Brian Ridout Wood Decay in Buildings, Conservation Approach for Care .
Cost
With all the maintenance methods, the cost of repair to repair the defects of buildings that allow the entry of water vapor will be the same. The overall cost of using environmental approaches for the treatment of dry spoilage is less likely than orthodox approaches.
Dr. Ridout cites a case study where the initial quote for orthodox treatment of a building is  £ 23,000 but subsequent treatment by environmental methods results in a third-austerity in wood repair and replacement work. Where it was decided to install moisture monitoring equipment, this would represent additional capital expenditures.
Warranty
There is a perception among the general public that dry rot is difficult to eradicate. It has "implanted fear and fear for centuries". Therefore, it is not surprising that property owners are told that they have serious problems, they will hope that drastic measures will be needed to improve it.
It can be said that, if reputable contractors and specialists are employed to manage orthodox care, this has the advantage of coming up with a guarantee of guarantee. Guarantees of dry rot recurrence began to be issued in 1950, covering processed wood for a period of 20 years. This period is immediately extended to 30 years.
However, the use of warranties has been questioned for the inclusion of clauses that exclude obligations if the wood is left wet again during the guarantee period.
One example of a court enforcing a guarantee is a case; Ackerman v Protim Services ;; (1988). In this case, dry rot repeated in bressummer about eight years after being treated for an outbreak earlier. The 20 year warranty issued by the maintenance company has a clause that excludes liability if the repetition is caused "failure to keep the property in dry and weather conditions and in good and proper maintenance condition".
The High Court of England declared that the guarantee was not disqualified by this clause because the wall where wood was built was damp due to the nature of the building's construction, not through the maintenance hose by the owner. But the obvious implication of this is that if the wood gets wet because the property owner does not maintain the building properly, then the guarantee will be void. In other words, the client is protected against the recurrence of dry decay provided that the conditions that allow dry decay to occur do not happen again.
Graham Coleman, a leading specialist in wet and wood spoilage, makes the same points on his website:
But then the dry wood does not rot - so what exactly is' guaranteed? Of course no chemical treatments have been applied because it is clearly implied that if the processed wood becomes moist it will rot. So what is the value of preservative care? Clearly no!
Therefore value assurance is questionable and may be difficult to enforce. However, the point remains that if the fungicide treatment is really effective, it does not matter whether the processed wood gets wet again or not. If, on the other hand, the fungicide wood cuts should be kept dry to make them rot, can not be more resistant to decay than untreated wood.
In fact, guarantees for the treatment of chemical dry decay may be dangerous as they can lure building owners to a false sense of security by allowing them to feel that they are capable of becoming less persistent with property maintenance.
Historic Buildings
Richard Oxley of Oxley Conservation states that many repair wood maintenance companies do not know enough about historic building construction to be able to advise on appropriate repairs and maintenance. He has an irreparable damage experience done through lack of knowledge (Oxley, 1995) just like Dr. Ridout.
The methods and approaches used to assess and repair timber in historic buildings have changed considerably in recent years, moving from wall irrigation, damage to decorative features during invasive survey work, and unnecessary cutting or chemical processing of wood.
With an emphasis on reducing the number of building fabrics to be eliminated, the environmental approach obviously has appeal to heritage organizations whose primary purpose is to preserve buildings. Many of these organizations support environmental approaches, such as Dr. Brian Ridout Wood Decay in Buildings, Conservation Approach to Treatment published jointly by the British Heritage and Historic Scotland. "Scientific Notes 24" historic Scotland advocates the use of environmental care from dry decay, as well as advice in the Society for the Preservation of the Ancient Buildings website.
See also
Wet (structural)
References
Source of the article : Wikipedia
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