To elucidate problems with microfungal infestation in indoor environments, a multidisciplinary collaborative pilot study, supported by a grant from the Danish Ministry of Housing and Urban Affairs, was performed on 72 mold-infected building materials from 23 buildings. Water leakage through roofs, rising damp, and defective plumbing installations were the main reasons for water damage with subsequent infestation of molds. From a score system assessing the bioavailability of the building materials, products most vulnerable to mold attacks were water damaged, aged organic materials containing cellulose, such as wooden materials, jute, wallpaper, and cardboard.

The microfungal genera most frequently encountered were Penicillium (68%), Aspergillus (56%), Chaetomium (22%), Ulocladium, (21%), Stachybotrys (19%) and Cladosporium (15%). Penicillium chrysogenum, Aspergillus versicolor, and Stachybotrys chartarum were the most frequently occurring species. Under field conditions, several trichothecenes were detected in each of three commonly used building materials, heavily contaminated with S. chartarum. Under experimental conditions, four out of five isolates of S. chartarum produced satratoxin H and G when growing on new and old, very humid gypsum boards. A. versicolor produced the carcinogenic mycotoxin sterigmatocystin and 5-methoxysterigmatocystin under the same conditions.

Indoor Mold, Building Dampness Linked to Respiratory Problems and Require Better Prevention; Evidence Does Not Support Links to Wider Array of Illnesses

The National Academy of Sciences

Scientific evidence links mold and other factors related to damp conditions in homes and buildings to asthma symptoms in some people with the chronic disorder, as well as to coughing, wheezing, and upper respiratory tract symptoms in otherwise healthy people, says a new report from the Institute of Medicine of the National Academies. However, the available evidence does not support an association between either indoor dampness or mold and the wide range of other health complaints that have been ascribed to them, the report says. Given the frequent occurrence of moisture problems in buildings and their links to respiratory problems, excessive indoor dampness should be addressed through a broad range of public health initiatives and changes in how buildings are designed, constructed, and maintained, said the committee that wrote the report.

The National Academy of Sciences

Fact Sheet on Damp Indoor Spaces and Health

Alliance For Healthy Homes

In 2003, the Centers for Disease Control and Prevention asked the National Academy of Sciences? Institute of Medicine to review the scientific literature regarding the relationship between moisture and mold in the indoor environment and adverse health effects. On May 25, 2004, the Institute issued its long-awaited final report, Damp Indoor Spaces and Health. The report presents a number of significant conclusions about the health impacts of moisture in homes and other buildings and makes key recommendations on how to minimize those impacts.

Alliance For Healthy Homes

Dampness and Mold Growth in Buildings:

A National Academy Study

Mold growth in buildings and its possible effects on human health have been in the news for several years while claims against insurance companies for mold and moisture-related problems in buildings have been on the rise, as has mold-related litigation. A recent report by the National Academy of Sciences Institute of Medicine has concluded that strong scientific evidence links mold and damp conditions in buildings to some health effects.

Insomnia is more common among subjects living in damp buildings.

Department of Medical Sciences, Sweden

BACKGROUND: Insomnia is a condition with a high prevalence and a great impact on quality of life. Little is known about the relation between and sleep disturbances and the home environment. AIM: To analyse the association between insomnia and building dampness. METHODS: In a cross-sectional, multicentre, population study, 16 190 subjects (mean age 40 years, 53% women) were studied from Reykjavik in Iceland, Bergen in Norway, Umea, Uppsala, and Goteborg in Sweden, Aarhus in Denmark, and Tartu in Estonia. Symptoms related to insomnia were assessed by questionnaire. RESULTS: Subjects living in houses with reported signs of building dampness (n = 2873) had a higher prevalence of insomnia (29.4 v 23.6%; crude odds ratio 1.35, 95% CI 1.23 to 1.48). The association between insomnia and different indicators of building dampness was strongest for floor dampness: "bubbles or discoloration on plastic floor covering or discoloration of parquet floor" (crude odds ratio 1.96, 95% CI 1.66 to 2.32). The associations remained significant after adjusting for possible confounders such as sex, age, smoking history, housing, body mass index, and respiratory diseases. There was no significant difference between the centres in the association between insomnia and building dampness. CONCLUSION: Insomnia is more common in subjects living in damp buildings. This indicates that avoiding dampness in building constructions and improving ventilation in homes may possibly have a positive effect on the quality of sleep.

Damp Indoor Spaces and Health

Board on Health Promotion and Disease Prevention, Institute of Medicine

Excessive indoor dampness is not by itself a cause of ill health, but it is a determinant of the presence or source strength of several potentially problematic exposures. Damp indoor environments favor house dust mites and microbial growth, standing water supports cockroach and rodent infestations, and excessive moisture may initiate chemical emissions from building materials and furnishings.

Indoor microbial growth?especially fungal growth?has recently received a great deal of attention in the mass media. It is a prominent feature of the breakdown of dampness control; its many possible causes include a breach of the building envelope, failure of a water-use device, and excessive indoor water-vapor generation. Occupants, health professionals, and others have wondered whether indoor exposure to mold and other agents might have a role in adverse health outcomes experienced by occupants of damp buildings.

Web Page

Building Enclosure Hygrothermal Performance Study, Phase I

Oak Ridge National Laboratories

Today, the City of Seattle announced the release of a technical study of moisture damage in newer buildings conducted by the Oak Ridge National Laboratories (ORNL). This research endeavor seeks to expand the knowledge base for regional builders, owners, and officials concerned about significant moisture damage encountered in recently built multifamily structures.

Summary
Study

OCCURRENCE AND CHARACTERISTICS OF MOISTURE DAMAGE IN SCHOOL BUILDINGS

J Koivisto, U Haverinen, T Meklin and A Nevalainen

A total of 30 school units, including 41 school buildings, were technically investigated according to a standardized protocol by trained surveyors, and moisture damage status of each building was assessed. Based on the assessment, the buildings were classified into two categories: 31 index buildings had notable moisture damage observations, whereas 10 reference buildings had not. This classification was used in order to evaluate the effect of different building characteristics, such as age of the building, predominant building materials, and type of structural assemblies, on the occurrence of moisture damage. Moisture damage characteristics, such as location of damage, damaged structure type, and presence of mold/mold odor, were analyzed in order to assess their distribution and inter relationships. With these analyses we seek further insights of such building- and moisture damage characteristics that may be significant for causes and effects of indoor air pollution related to excessive moisture in school buildings.

Characteristics of Moisture Damage in Houses and Their Association with Self-Reported Symptoms of the Occupant

J Koivisto, U Haverinen, T Meklin and A Nevalainen

This study was motivated by a need to establish criteria for evaluating observations of moisture damage with respect to exposure and adverse health effects. The database used included information on moisture damage from 164 dwellings and questionnaire data collected from the occupants. Moisture damage observations were classified according to eleven variables characterising damage by, for example, size, duration and type of damaged material. Five health symptom scores were devised based on the questionnaire data. Visible mould associated with respiratory infections, irritative and skin symptoms. Damage <1 m2 in size was associated with general and skin symptoms, and >4 m2 in size associated with respiratory infections and skin symptoms. Damage of <3 years duration was associated with respiratory infections and damage that had existed for 3-10 years was associated with general, irritative and skin symptoms. Symptom scores were associated more frequently with damage to organic rather than inorganic materials. Criteria used to evaluate the association between the classification of moisture damage and symptom scores were excess risk compared to a two-category classification, dose responsiveness, and biological plausibility of the findings. Despite the complexity of interpretation, the results show that more accurate models of moisture damage with respect to exposure and adverse health effects can be established.

Weblink

Mold & Moisture Intrusion Case Study Report

Kevin Powell, National Centre for Housing& The Envrionment

In this study, the NAHB Research Center investigated building issues related to elevated moisture at 18 sites representing more than 20 residences. The case study reports list symptoms, possible moisture sources, diagnoses and prescriptive remedies for the problems, and analysis of remedial measures if the builder or homeowner adopted the measures. Cases included several areas of the country representing the northern heating climate, the southern cooling climate, and the mixed climate zone situated between the two.

Document

Influence of Curing Conditions on Water Loss and Hydration in Cement Pastes with and without Fly Ash Substitution

Dale P. Bentz

The proper curing of concrete is paramount to achieving desired strength and durability performance in the field. Because blending components often react at different rates from portland cement, blended cements may require that special attention be paid to prolonged curing. This report summarizes an exploratory study on the influence of curing conditions on water loss and hydration in ASTM Type I and blended portland cement pastes with a water-cementitious materials ratio (w/cm) of 0.40. The blended cement contains about 20 % by mass fly ash substitution for cement. Water loss/gain under various curing conditions is monitored both globally by bulk mass (loss) measurements and locally using the NIST X-ray absorption apparatus. Hydration is assessed based on the measurement of non-evaporable water content after 31 d of curing. Curing conditions include no curing (exposed to the environment throughout the curing period), sealed curing, and saturated curing for 1 d, 3 d, and 6 d. The cement paste with the fly ash substitution is observed to be more sensitive to curing conditions than the conventional Type I portland cement paste.

Rising Damp

Tim Hutton

Rising damp is widely misdiagnosed in existing buildings, based on the incorrect interpretation of visual evidence and the readings of moisture meters. Because of a highly successful sales campaign over the last 20 years by specialist remedial contractors installing injected 'chemical dampproof courses', this misdiagnosis of rising damp has also become synonymous with a diagnosis of a lack of an 'injected chemical damp-proof course'. Although this has been very good for business, it has often resulted in a waste of the clients' money and resources; original plasters and finishes have been destroyed in the process of installation, and unnecessary damage has been caused to original structures by the drilling of irrigation holes. In addition, money that might have been spent on more cost-effective maintenance or repair works has been wasted.

Rising Damp

Preventing Moisture Damage

National Paint & Coatings Association

The next time you take a shower, consider the damage you may be causing to your home. Actually, one shower won't cause moisture damage in itself, but together with washing clothes, steam from cooking, and dishwashing, a good deal of moisture is added to the atmosphere of your home each day. And on the outside, rain and snow regularly drop a good deal of moisture on your house. All these factors can cause extensive damage both to your home's appearance and structure. Moisture can cause ugly rusting or decay of building materials, and blistering or peeling of painted surfaces. It can warp wood, and promote mildew and other fungi growth on our home.

But moisture need not be a menace, if you are aware of its threat and take the proper steps to prevent its accumulation in unwanted areas of your home. You should understand how moisture damage occurs, learn how to prevent future damage, and know how to repair present damage.

Weatherproo?ng Masonry For Northern Climates

The enduring strength, beauty and performance of a brick wall assembly is critically dependant on three components: design, workmanship and materials. If even one of these factors has not been diligently applied, integrity of the wall assembly is compromised.

The single most important factor to be understood and designed for in the severe northern climate is moisture control. Seldom does failure of a brick wall assembly occur without the presence of an excessive moisture load. Excessive is de?ned as being more moisture than can dry out of the assembly before that assembly freezes due to ambient temperature conditions. The trapped moisture will freeze and thaw and may cause deterioration known as spalling, in which part of the brick surface may break away.

Moisture Control in Houses: The Effect of Interior Moisture on Exterior Finishes

John Leeke

Moisture movement and control is a major concern to building designers, builders, and homeowners. Where moisture problems exist, they can range from simply being a nuisance to actually threatening the life of the building. Moisture in vapor form is usually not a problem, but it becomes a problem when it condenses as free water on cold surfaces. The following discussion addresses the mechanisms of moisture movement and condensation, the effects of interior moisture on exterior finishes, and methods of controlling this movement to prevent problems in houses.

Sulphate attack on ground floor slabs is a very serious problem which can cause structural damage to the main walls of a building. The problem occurs when the fill material (hardcore) beneath the slab contains sulphates and these migrate into the concrete. The sulphates react with the concrete causing it to expand. This results in heave of the slab and structural damage to the external walls as the slab pushes them out. Eventually the concrete may disintegrate. When the slab heaves, any internal walls built off the slab will be lifted and may cause damage to the structure above.

Damp Report

It is normal for a Building Surveyor to employ a damp-meter at random locations to check for any damp to the internal walls. The cause of any damp is usually fairly obvious, although not always so. Typically, when a Surveyor requests a Damp Report, it is to confirm that the cause is rising damp, to determine the extent of the problem, and to get an estimate for remedying it.

A typical Damp Report will identify those (readily accessible) areas where damp is present and will identify the cause, along with recommendations for any necessary repairs or remedial works.

Effects of Aggregate Coatings and Films On Concrete Performance

Karl Gullerud and Prof. Steven Cramer

Coarse aggregates containing surface coatings were collected throughout Wisconsin and characterized to determine composition. Based on the results of these tests, a subset of the sample aggregates was selected to further study the effects of the coatings on concrete performance. It was hypothesized that coatings consisting of clay material are more deleterious than coatings consisting of either dust or carbonate material. The 10-batch concrete mixing plan tested coarse aggregates from three different sources and in the following three conditions: (1) coated aggregates that were sampled in the field, (2) aggregates washed in the laboratory, and (3) aggregates with added coatings. The effect of each aggregate coating on concrete performance was assessed from changes in compressive strength, tensile strength, drying shrinkage, freeze-thaw durability, and chloride ion penetrability as influenced by washed versus coated aggregates. In general terms, this research suggested that the effects of aggregate coatings as sampled in Wisconsin are minor, but could not rule out the possible existence of problem aggregates not included in the small sample. The test results confirmed that coatings with a high clay contents are more deleterious to concrete strength and durability than coatings that consist largely of dust or carbonate material. While the carbonate coatings appeared to slightly improve performance, the clay coatings appeared to significantly decrease strength and durability. Although current field washing procedures do not need to be changed, it was recommended that the WisDOT consider adoption of the California Test 227.