Fungus In Indoor Climates Construction Essay

Published: Last Edited:

This essay has been submitted by a student. This is not an example of the work written by our professional essay writers.

This report is a compulsory 5th semester assignment of constructing architect education. Report will deal with fungus as a sub-topic for indoor climate. The issue would be best summarized in a form of a question: Does the public know enough about fungus in order to prevent it?

Fungus is a common problem in many old and new buildings. The growth of mold provides bad indoor climate, which has a remarkable impact on a human health. Therefore it is important to identify the size and importance of the problem. The attention for this topic is supposed to give readers the relevant knowledge and awareness of the issue, in order to motivate them and take an action to improve the climate indoors.

The knowledge gathered in this report is intended for the architects, constructing architects, medics, people suffering from moulds, their relatives and others interested in human health and sustainable building design.

The case

I questioned 12 people in order to find out their knowledge concerning moulds and their influence to human health. I was trying to keep the basic criteria then choosing respondents fulfilled: respondents must not be younger than 18 years, diversity must be achieved - wide age range and different nationalities. As a result the youngest respondent appeared to be 19 year old, the oldest - 75 years. Respondents were the citizens of Denmark, Lithuania, Italy, Czech Republic, Spain, Sri lanka residing in Denmark and Lithuania. The questionnaire was done by sending e-mails and one person was questioned by the telephone.

The questionnaire consisted of 8 basic questions:

What do you think moulds are?

Why do you think they appear?

How you think molds can affect the indoor climate?

Have you been having moulds in your home before?

How did/would you react to the problem?

Do you have allergy to moulds?

Where would you get help from in case you notice moulds in your home?

How would you prevent mould?


The main purpose of analysis is to be able to compare and relate the real case with the learned literature in order to be able to find out the difference between the scientific knowledge about moulds and in practis - the actual society knowledge about it. I wil analyse to find out how much the lack of knowledge about an issue increase the risk to have bad health caused by moulds. During the process I will seek to come up with an objective solution/sugestion for the case.

I will compare each question with another and to get an overwiev and define statistically how different people answered to the same question and finaly compare with the literature and make a small subconclusions about it. Same process will follow for each question.

Introduction to moulds

Starting with the first question each respondent were asked to explain what does he think moulds are.

As a result 8 from 13 respondents answered that it is a fungus and the answer was corect. Other respondents did not specified exactly, so I assumed, they were not shure about it (3), or did not know anything about it (2). 1 respondent was mixing up moulds with the bacteria, another were guesing that it is a life form similar to fungus.

''Moulds are a type of fungus. Larger fungi include mushrooms. Moulds are multicelled, as opposed to yeast which is single-celled." (

Even after several years of extensive research is still not enough

knowledge collected about moulds .There are no such set of safe limits

when mould -- exist everywhere in nature - are unacceptable

for users of buildings.

Mould spores are everywhere, and by favourable growth conditions (humidity)

they start to grow and form mycelium (mould mildew), where new spores are formed.

In nature, mould usually gives no problem.

The mould that grows - visible or covered- in our buildings, may in certain circumstances lead to health problems for sensitive persons. Mould spores only grow in buildings which are exposed to huge amounts of moisture, for example; if constructions are moistened or Relative humidity is high.

Moisture of structures can, for example appear due to the leaks in the roof or walls, rising ground moisture, leaks in the damp proof membrane or cold bridges.

High humidity can be, for example due to the lack of heating, ventilation and venting - Particularly if the clothes are dried indoors.

Growth conditions

Mould growth requires longer time of moisture exposure - from weeks to months. If the moisture level decreases, mould goes in a sort of hibernation, which do not generate additional mould growth. Moulds are very tough and can grow on most building materials where they live or by the materials or by dirt on them.They can live in both the visible surfaces as inside the cavities in structures and ventilation systems - there sufficient humidity is present.

Moulds usually grow slowly and mainly on material surface. Growth happens best in organic material and require a relative humidity of approximately 70% (surface). Moulds grow best at temperatures between 20 °C and 30 ° C. at lower temperatures fungus grow slowly, and growth is usually stops when the temperature falls below about 5 ° C. Moulds do not require light to grow.

The fungus, which can break down or transform materials, can take place inside the material while there is mould growth is on the surface.

New growth of tree decaying fungi usually occurs only when the moisture content of wood

reaches above 20%, equivalent to 87% RH in the surrounding air.

Moulds do not break the materials they grow on.

Causes of mould growth

The causes are multiple. They include:

• Residents inappropriate behaviour, including lack of ventilation,

• lack of or late action to signs of moisture damage in the form of condensation, damp stains or leaks,

• design errors regarding structures or installations,

• execution errors that give rise to incorporation of unacceptable levels of water and moisture,

• execution error, which leads to constructions and installations is not working as planned.

This means that there is a need for prevention efforts from several sides. It is therefore important that users, services in charge, designer and contractors - all contribute to reduce the moisture and mould from growing.

Dry rot fungus

One of the most serious wood decaying fungi in buildings - dry rot fungus both grow rapidly and break down the tree and can spread into the porous, inorganic materials such as masonry. Dry rot fungus develops often hidden inside moist constructions, and it is

therefore important to be aware of the specific external characteristics of attack

and that an attack could grow further if prevention is not done enough thoroughly.

Dry rot fungus grows quickly and can - once established - get water and nutrients over many meters through its string mycelium.

It can also extract water, if materials or environment is too humid.

Spores from the dry rot fungus does not grow on healthy tree, but if the wood is first attacked of other fungal species - or if new wood is brought into contact with infected tree - establishes easily.

By drying dry rot fungus goes in sleep, but growth continues, if moisture is added again. Dry rot fungus can - depending on including humidity and temperature conditions - Keep several years in sleep mode, but under constant drying conditions fungus mycelium will die.

It is therefore important to control the fungus growth:

• make proper identification

• determine the attack extent

• remove moisture and stop the moisture source

• repair / control with care.

Note that the use of non-controlled recyclable materials can cause risk of fungal attack, including attacks of dry rot fungus.

It is usually relatively easy to distinguish between Dry rot fungus and other tree decaying

fungi (fig.1)

At the slightest doubt on the attack type sent a sample to a laboratory

identifying tree decaying fungi.

Occurrence and growth conditions

Dry rot fungus can occur anywhere in buildings where there is mortar, cement or calc containing material. Fungus is forming oxalic acid, which can be neutralized by the alkaline materials.

Fungal preferred temperature is approximately 20 °C and the optimum tree moisture is20-30%. It grows mainly in damp, enclosed constructions.

Distinguishing features

Dry-rot fungus forms brown humus to decompose wood cellulose. Wood

decomposed by dry rot fungus is grey brown and formed strong and deep

cracks (crack bricks) on along and across the wood fibres with 3-7 cm apart (Figure 1).

Tree's strength is getting reduced and this may give security risk - especially at

supporting structures. Sometimes, for example, rafter boards fall down because they cannot carry plaster layer or the floor and stair construction collapse.


Most of the fungal mycelium is in the tree or hidden in materials and structures. It usually develops a characteristic surface mycelium, who is initially white and looks like cotton wool

(Figure 4,5). Later it becomes grey and membrane-like. There formed almost always a string mycelium, spreading of cracks, crevices and structure otherwise (Figure 4, 12). String thickness varies from sewing thread to pencil piece. They are thick, stiff, dry, and then bending they breaking with a little pop.

Fruit bodies'

Dry rot fungus forms fruit bodies with the influence of light (Fig. 2, 3).They are loosely stitched to the ground, easy to remove and are either flat like pancakes or console-shaped -without a hat and toxic in contrast to mushroom.


The central part of fruit body coloured eventually brown of one million microscopic spores released from the fruit body. This is often observed at the floor, window sills and other horizontal surfaces covered by a layer of spores looking like cocoa powder (Figure 6).


Dry rot fungus can attack wood everywhere buildings - not necessarily woodwork. The attacks often develop in secret and can therefore be comprehensive,

before they are discovered.

This is because the dry rot fungus:

• can grow out of masonry, from which it may spread to other woodwork

• requires very little water to be active. Unlike other tree decaying

fungi dry rot fungus is not so easy dying through normal drying. The attacks often first detected in with the appearance of fruit body or deep building studies.

Repair Method

The repair of damage after infection made by Dry rot fungus must be performed more carefully than other fungal attacks. For making good result it is essential to clarify fungus

reason (s) and especially moisture source (s) thoroughly.

Based on surveys and assessments, repairs should start before an execution plan is prepared.

Method of choice is driven by both economics and the actual design as an example in

what extent the woodwork strength is so weakened that it is necessary to change it , and how easy a replacement could be performed.

Fight with dry rot fungus applies to:

• Replacement and impregnation (fig11) - the traditional method.

• Drying and repair

• Heat treatment using such as hot air, radio frequency, infrared radiation, or microwaves.

• A combination of the above methods.

If the method does not ensure the fungus mycelium from drying out (Figure 18), the moisture conditions subsequently evaluated carefully in a longer period.

As part of the method choice of environmental and safety conditions are into account.

Reasons for fungus/moulds

Secondly, the repliers were asked what do they think are the reasons for fungus/moulds. Most of the respondents which was 9 out of 13 mentioned high humidity as the main reason of the problem. 6 repliers out of 13 mentioned wrote the ventilation as the main or an additional reason. 1 person had no opinion about it. Other: 1 person mentioned wrong choice of materials and another wrote about insufficient isolation and added humidity and ventilation.

More or less respondents were right at least partly about it. Some persons seemed to be mixing up what is coming first: bad ventilation or humidity. It is known that dampness in the construction is caused by insufficient ventilation then the moisture cannot escape from the building. Putting thick layer of insulation into the walls cannot prevent the mould growth. It is important to solve the cold bridges correctly to avoid having additional moisture from the outside into the house causing condensation on the surface. Last but not least, it is necessary to avoid cold surfaces on the walls by placing the dam proof membrane in the right way, additional attention must be paid to the north facing wall, which is constantly exposed to big amounts of cold wind. Sometimes rising damp from the ground, roof which is not tight or leaking pipe can be the case The last mentioned can be a serious problem then the leakage is very small so it takes time to find out where the moisture is coming from. None of the respondents mentioned habitant's bad habits such as not ventilating the house, drying clothes inside, keeping different temperature in the rooms, not using cooker hood and exaust system, keeping the surface wet after bathing or cooking.

Affect to the indoor climate

Thirdly, the repliers had to answer: how they suppose fungus/moulds affect the indoor climate? Most respondents mentioned smell which was 6 out of 13. That is quite logical because our odour centre is very well developed so that we can feel the smell immediately but otherwise to get the first symptoms it might take some time if a person haven't been faced to moulds before so he/she does not normally have an increased sensitivity to it. 5 people out of 13 mentioned health problem. 2 respondents remarked this as the only problem, others 2 as additional problem, 4 out of 5 mentioned shortness of breath as the main factor of bad health due to the moulds. It was assumed that 4 out of 12 people don't know anything about it. 1 of them have written that the indoor climate is becoming very wet but this is not the case that gives uncomfortable feeling for the people. One of the respondents were guessing that some species of moulds are bad for the indoor climate although actually any mould species staying in the house have negative effect for human but one are more dangerous than the other.

To conclude with, fungus/moulds are first noticed because of its strong musty smell which is produced by "mVOC's - "mickrobial volatile organic compound's released into the air by living mickrobial organisms"(Jørgen Bech-Andersen, Indoor climate and moulds, 2004). People define the smell different: as a haystack, summer cottage, cellar, sewer or sweating feet.

Fungus/moulds growing both visible and hidden in the constructions will have an impact on the indoor climate through production of VOC's.

Health irritation

Mould spores can be annoying, both while they are growing and when they dry out or dying, and possibly mixed with dust (fig.1) Therefore, the proper cleaning acts a large preventive role. Dead mould spores generate usually only if they are inhaled. They must

therefore not present in abnormal quantity in the air in space where the users reside. Then

they are swirled up with dust, mould spores can get contact with mucous membranes and respiratory tract for persons staying in the room.

During growth moulds will deliver biologically active substances that can spread through both - air and some building materials. It is therefore can be larger quantities of mould growth in both- open or closed building construction.

Limits unsolved

Despite more than 10 years of research is the relationship between the presence of mould spores and health problems are far from finally resolved. There are no such set of safe limits of how much mould growth can exist in or on structures before it is unacceptable.

There is a great variation sensitivity of persons depending on individual case - For example, especially children susceptible to mould, and women are generally more sensitive than men.

Mould spores are everywhere so it may be difficult to determine whether a building health problems are due to impacts from construction-related mould or other conditions that gives similar symptoms.


Symptoms, which in some cases can appear then a person is exposed to mould:

• mucous membrane irritation of eyes, nose, throat, skin.

• fatigue and headaches, concentration loose

• Allergy to mould. Allergy is most common towards Cladosporium and Alternaria. These and other fungi are often found in nature as well.

For some people the symptoms are so irritating that they find it difficult to live in buildings and rooms with mould.

Simptoms are generally smaller in summer than in winter. This is mainly due to the greater air circulation because of open windows and doors, then concentration of harmful substances in indoor air is reduced.

To determine whether observed symptoms are caused by moulds, it is recommended to seek the assistance of a person with special knowledge, linked between health and mould growth. The doctor may also examine whether the symptoms are caused by an allergy to mould or allergies to other factors.

Long-term effect

There is no evidence that mould in the indoor environment leads to long-term effects.

The past few studies of mould infected buildings, that are renovated, shows that the symptoms disappear. However, there may be individuals, that still have the symptoms mentioned long after a refurbishing.

Having moulds at home

To the 4th question - Have you been having moulds at your home before? - repliers answered in this way: 7 respondents out of 13 newer had moulds at their home, while rest 6 responses were positive. So 53,8% of the respondent answered negatively and 46,2% positively, which means that the mould problem is very huge and important.

To the 5th question - How did/would you react to the problem? - 3 of those who never been faced to the mould problem did not replied to the answer. As a result, it can be assumed that they probably don't know how they would handle the problem. The results of the rest who never had experience before are these: 1 respondent was not very specific - he would find the case first, and take an action after (It is true that to find out what causes the problem is the best way to start.); another one would clean the surface and whitewash ( once again finding the cause first and then handling the problem, it is important to notice that after the wall is washed, the area have to be observed and if the moulds do not appear again than a covering may be applied.); the 4th respondent knew that the surface need to be removed, chemical applied and the surfase restored (any it depend on a certain case and the size of the damage, it is not always necessary to remove the materials); only one was the most right answering that it is important to much moulds are extended, after to know the cause and fix it by using dizinfection (it is good to know that if the damage is big few different steps or combination of them must be applied: konstructive protection, chemic protection, heat protection). Those who have been faced with the issue before mostly answered to have been using certain chemicals to remove the moulds - one applied paint to the wall after, another was ventilating the room more.

5 simple steps to follow for removing the mould from your home:

Check your house thoroughly to find the reasons for mould. Do the exhaust and cooker hood work properly? Are there any cracks in window seals or water damage to the building? Do you remember to ventilate to take the moisture away?

Remove the cause.

In smaller areas clean the mould with desifective cleaner (e.g. Clorine or Rodalon). Leave the chemical for 20 min and wash it afterwards.

Check to see wheather moulds comes up again.

Contact the maintenance staff in your building or the insurance company /company dealing with moulds (for private housing) if you cannot solve the problem yourself.

Allergy and inheritance

The 6th question was asked to find out how many people are having allergies. 7 respondents have no allergies, 4 replied having the allergy. 2 repliers admitted not knowing about their allergenicity. Fortunately none of the respondent which participated in the questionnaire appeared to have the allergy to fungi/moulds, but 1 respondent having personal experience with moulds added that his children had a big allergic reaction then the mould were present in their home.

As a result, 30,8% suffer from allergies, 53,8% are having no allergies, 15,4% don't know about it. So in actual people with allergies could be much more than 30,8%. Many people don' t know being allergic unless they get symptoms, even though the person might mix it with the normal cold. Allergic reaction finish then the cause has disappeared.

The symptoms of all types of allergies are similar and sometimes persons are having few types of allergies therefore it is not always easy to identify if f. eks allergy is caused because of moulds.

However talking about any kind of allergy one factor is significantly important -Inheritance is a major allergy factor.

A child whose parents or older siblings, have no allergic disease, have 5-10% risk of developing some form of allergy.

A child has special risk of developing allergies if to mom, dad or older siblings allergic diseases have been diagnosed. That means that child have a special risk to get a disease, but the question is what kind.

All children can get allergy but risk is the biggest then one of the parents or siblings are allergic. Children of allergy families inherit a tendency to develop allergies.

In Denmark approx. 5-8% of newborn children are double disponed to develop allergic disease. Child is double disponed if both parents have been diagnosed having allergy. Double disposition means that the child's risk of developing allergy increases 40-50%. If parent with the same type energy it increases to 70%.

In Denmark there is approx. 1/3 of newborn children which are singledisponed to develog allergic disease. Child is dispositioned if to single family member allergy have been diagnosed. In such case child risk to develope allergy increases the risk to 20-30%.

The interesting fact is that allergy to mould is estimated to be 3-6% of the population or 150000-300000 people.

Where to get help from?

To the 7th question - Where would you get help from in case you notice moulds in your home? - 8 repliers suggested their solutions: internet, cleaning company, professional company dealing with moulds, friends with experience such as architect or engineer, public health office. 2 respondents seem to misunderstand the question: they would get help from liquids. Unfortunately it does not answer to the question. This misunderstanding could have occurred very likely because of poor language knowledge of the respondents (questionnaire was held in English) or the wrong formulation of the question. The rest 2 persons admitted to knowing what to do in such case.1 person answered that he would contact the insurance company to examine the damage and use the internet to find out more.

It is no doubt the majority would find the way to solve it, but in order to save the precious time it is good to know the shortest way to the solution (depending your type of residence):

If resident is living in Public housing and have tried to solve the problem without a success, he should contact his housing office. They will start to search for moulds in the home. It can be necessary to continue the following technical examination after the first visit. If the examination shows that there are moulds in the home, moisture problems must be solved and infected area must be removed/treated.

Then mould has appeared due to the wrong use of the home, f.eks. Insufficient heating or ventilation, resident is held responsible to remove the moulds and repair the damage. If that is not the case then the housing office is responsible to solve the problem.

If the person disagrees with the housing office of how the mould problem should be solved in his home, resident can contact the board of the department.

The department board have contact with many residents. In this case residents questions and claims will be heard. It is important that the office understand the residents and housing office role in relation to the mould prevention. So the department board can help by giving advise what to do.

Then planning the budget it may be important to collect some money to renovate or maintain f.eks. Ventilation system, which helps to prevent mould. In the long run prevention is cheaper than spending much money to repair the damages.

If resident is living is private rental building and have tried to solve the problem without a success, he should contact the landlord. He will search and examine the moulds. After the moisture problem must be solved and infected area removed/treated. If the moulds have appeared due to the resident and wrong use of the house, he is held responsible for the solution. If the moulds appeared because of poor construction, it is the landlord responsibility to solve the problem.

If the landlord does not respond to the resident matter, or if the resident disagree about the problem solution, resident can contact the rent board. The rent board can only judge the landlord failure due to maintenance but it cannot make the landlord do the improvements to prevent mould.

If you disagree with the rent board's decision or if the Board cannot judge, you have the possibility to bring the case to the Housing Court.

The local council duty is to supervise the housing and buildings. This means that the local council must respond if it becomes obvious that dwelling is contaminated by mould. Resident must contact the local council if landlord do not follow up resident request within a reasonable time.

Resident can contact the local council if landlord do not follow up on his request within a reasonable time. Resident can also contact the local council also because of the rent board's decision.

If resident disagree with the local board's decision, he has the possibility to refer it to the Urban Renewal Board. Resident can do this if the issue is the understanding of the law or if the municipal council's decision after the Board's assessment have general interest or higher significant consequences for him.

If the person is the owner of the house and have tried to solve the problem without a success, he should contact his insurance company. They will send the person to search and examine moulds in the house. Company will evaluate the damage and cover the reparation expenses if the problem have occurred not because of the owner fault. In the opposite case owner himself must cover the expenses.

Mould prevention

To the last question - How would you prevent mould? - 5 respondent answered that rooms need to be kept ventilated and dry. Few persons mentioned that it is necessary to keep certain humidity in the house, one wrote about the keeping of higher temperature in the house and one remembered that the walls need to be dried up after showering. 1 replier had no opinion to the question. 3 persons answered that house need to be kept dry while isolating the walls. 3 respondets replied that house need to be ventilated. 1 respondent mentioned the importance of the right choice of the materials and correct maintenance.

Many respondents were not specific of how to reduce moisture in the house. Some of them forgot that house cannot be kept dry without ventilating it.

By following simple tips you can prevent the mould and improve indoor climate:

Remember to ventilate 5-10 min. 2 or more times a day.

Be extra careful with ventilation in the bathroom and the kitchen when you've had a bath or cook -dry out the wet surface.

Always use the extractor fan when you cook, use lids on pots. Check that the exhaust vent is working as it should.

Hang clothes to dry outside or use a dryer.

Keep the same temperature in every room in your home. The temperature must be no lower than 18 degrees. Avoid open connection between the warm /damp rooms and unheated spaces - close door to the bathroom during and after bathing while ventilated.

If there is water damage, be sure to contact the housing office or your landlord, so the damage can be repaired as soon as possible.

Keep fresh air vents in window frames and walls open and see if the ducts and exhaust valves operate well and are clean. Contact housing office or your landlord if you are in doubt.

avoid placing furniture or create so close to the cold outer walls, the heating of the surface is prevented and here is a risk of condensation.

clean the surfaces - it has a major preventive important because any fungal spores removed.

ensure that even small water damage is repaired quickly - and that the cause of the damage removed!


The small statistics I have made, gave some basic idea, about residents in relation with fungus/mould problem. The result could have been more precise if more residents would have been questioned. The questions were not formulated in a very good way - some misunderstandings have occurred, because they were not specified enough. The results could have been even better if the respondents would be questioned alive, so it would be easier to make sure that both sides have understood one and the another correctly.

However the test shows that Fungus/mould is a really significant problem. Many people don't know what precautions must be taken to prevent it. Residents use the buildings without thinking and the problem is taken serious only by the time then it already appeared.

The situation could become better when the people would read more about the issue :get to know real cases and the extent of the dammages, possible long lasting health effects and so on. At the end hopefully people can understand the effects and become self-concious about their actions.

Literature list

Jørgen Bech-Andersen, Indoor climate and moulds, 2004

Jørgen Bech-Andersen, The dry rot fungus and other fungi in houses, 1995

BYG-ERFA erfaringblader:

Ægte Hussvamp- identifikation og reparation af skader,

Skimmel i bygninger - vækstbetingelser og forebyggelse