Moisture Problems Research Articles

Moisture problems of functional joints of wooden windows – causes analysis

The article addresses the issue of the humidity regimen of a functional wooden window joint. Current energy-saving trends in the buildings bring secondary effects associated with indoor climate change. Increase of the thermal-technical quantification, non-breathability, and diffusion resistance of the building envelope without the solution of controlled ventilation brings an extreme rise of the interior moisture. The passage of moisture through a functional joint is ensured mainly by exfiltration. The energy standard applicable after the year 2020 assumes buildings with almost zero energy need that cannot be reached without a recuperation system. The concept of the recuperation systems usually works as a pressure system, which increases the likelihood of exfiltration. Measurements done in a large climate chamber show that the diffusion of water vapor can overcome the infiltration flow of the outside air. The passage of moisture results in icing or condensation in the functional joint, which subsequently damages the surface treatment of the wood. Another serious defect is the subsequent mold growth.

A procedure to evaluate the most suitable integrated solutions for increasing energy performance of the building’s envelope, avoiding moisture problems

A procedure to evaluate the most suitable integrated solutions for increasing energy performance of the building’s envelope, avoiding moisture problems

Dampness and Moisture Problems in Norwegian Homes.

The occurrence of dampness and mold in the indoor environment is associated with respiratory-related disease outcomes. Thus, it is pertinent to know the magnitude of such indoor environment problems to be able to estimate the potential health impact in the population. In the present study, the moisture damage in 10,112 Norwegian dwellings was recorded based on building inspection reports. The levels of moisture damage were graded based on a condition class (CC), where CC0 is immaculate and CC1 acceptable (actions not required), while CC2 and CC3 indicate increased levels of damage that requires action. Of the 10,112 dwellings investigated, 3125 had verified moisture or mold damage. This amounts to 31% of the surveyed dwellings. Of these, 27% had CC2 as the worst grade, whereas 4% had CC3 as the worst grade level. The room types and building structures most prone to moisture damage were (in rank order) crawl spaces, basements, un-insulated attics, cooling rooms, and bathrooms. The high proportion of homes with moisture damage indicate a possible risk for respiratory diseases in a relatively large number of individuals, even if only the more extensive moisture damages and those located in rooms where occupants spend the majority of their time would have a significant influence on adverse health effects.

Moisture damage with magnesium oxide boards in Danish facade structures

Magnesium oxide boards have been widely used on facades in Denmark during 2010-2015. However, the magnesium salts absorb humidity from the ambient, and they begin to leak salty water, which is highly corrosive, and leads to moisture and mould problems in wooden members of the structures. MgO-boards were not tested for their hygrothermal function before being used on exterior wall structures, which has had detrimental consequences, such as an expected cost of repair of around 2 billion DKK. Properties for moisture transport and retention properties have been determined and will be shown together with some examples of damaged structures.

Analysis of evapotranspiration processes in the Sassi of Matera (southern Italy)

The Sassi of Matera (Basilicata region, southern Italy), inhabited since the Paleolithic period, has become an important tourist attraction in recent years. This interest has led to remarkable restoration of homes excavated in the tufaceous rock and suffering from severe moisture problems. To improve indoor hygiene conditions, the best way is to install HVAC systems. However, designing these systems must take into account the water coming from the walls. The awareness of the amount of water released into the environment due to evapotranspiration could be of great help in dimensioning the HVAC system. This paper illustrates the first results of a numerical analysis of the interaction between the mass of wet tuff and the internal environment of rock-clad dwellings.

The Importance of Building Physics in Improving the Quality Control of Buildings – The Role of Public Authority

The Building Supervision Offices (BSO) grants building permissions in Finland and take care, that buildings are built according to building codes. BSO in Oulu has taken more active role in aim to increase energy efficiency and quality control. BSO has also participated in several R&D-projects. BSO in Oulu created a moisture management procedure for buildings in the beginning of 2000, because of very tight timetables of new construction and moisture damages already occurred. The goal was to decrease moisture problems by systematic control in the building site, and the companies took this procedure into use. The moisture related damages have been reduced. The next step was to create a quality classification procedure for one-family houses, applied in Oulu Housing Fair 2005. Special attention was paid to air tightness. The average level in Oulu area before the BSO actions was approximately n50 = 4,0 1/h and when BSO begun to develop the air tightness guidelines by voluntary base, the recent air tightness level is 1,0 1/h, best value has been 0.08 1/h.BSO has done various instruction cards, now more than 50, published as a guideline available for new and existing buildings and organized continuous training events and workshops on average 1/week. Latest card is building commissioning (Cx) including all measures in takeover-stage. The latest project is “Drychain10”-concept together with all participants in whole building process funded by Finnish Ministry Environment (1. award in Building Physics-seminar Tampere-2015).At the moment, there are more than 1000 on-line measuring sensors in pilot buildings in Oulu. These results can be exploited in building physical modelling of constructions. The goal is to improve the performance of buildings and verify the level which should be better than the level based on the codes. In this presentation, the role of public authority and results of quality control efforts are introduced.

Effect of air leakage on the hygrothermal performance of highly insulated wood frame walls: Comparison of air leakage modelling methods

Air leakage is one of the important moisture sources that may increase the risk of moisture problems in wood frame walls. Two simplified air leakage modeling methods, i.e. air convection method and air infiltration method, can be implemented in commonly used hygrothermal models. This paper investigates the applicability of these two methods in evaluating the hygrothermal performance of three types of wood frame walls: one baseline 2 × 6 wood frame with fiberglass insulation, two highly insulated walls, i.e. deep cavity wall with I-joist framing and cellulose fiber insulation and 2 × 6 farming with exterior polyisocyanurate insulation and fiberglass stud cavity insulation. Firstly, the hygrothermal models are calibrated by comparison to measurements. Then the best matched models are used for two years' simulation to evaluate the mold growth risk of these walls at various airtightness levels. The results show that both methods can model the effect of air leakage reasonably well by adjusting the position of air layer in the air convection method and the amount of the indoor air reaching the condensation plane in the air infiltration method. The air infiltration method tends to overestimate the moisture content of OSB sheathing, while the air convection method tends to underestimate the moisture content of OSB sheathing. The baseline wall has higher mold growth risk than the I-joist wall with cellulose fiber, while the I-joist wall's mold growth risk becomes slightly higher than the baseline wall when the insulation materials are changed to fiberglass. The exterior insulated wall has no risk of condensation and mold growth.

Bloques de concreto con emulsión de parafina

Los muros de las edificaciones presentan frecuentemente problemas de humedad como consecuencia de la exposición a la lluvia y la absorción de agua del suelo. Infortunadamente, los bloques de concreto convencionales adquiridos en el mercado tienen coeficientes de absorción capilar altos y resistencias a la penetración de agua bajas.En esta investigación, se produjeron y analizaron experimentalmente bloques y probetas cilíndricas, se fabricaron con arena de concreto lavada, cemento Portland tipo 1, emulsión de parafina y una relación agua-cemento de 0,40 en peso. Se estudiaron bloques y cilindros sin emulsión de parafina y con 10%, 20%, 30% y 40% de adición de emulsión de parafina respecto al peso del cemento. Se ejecutaron ensayos de absorción capilar, de resistencia a la penetración de agua y se realizó un análisis comparativo de los resultados obtenidos para determinar la proporción óptima de adición de emulsión de parafina.Se determinó que los bloques con emulsión de parafina presentan mejores propiedades que los bloques convencionales sin aditivos y que podrían reducir los problemas de humedad en los muros pues tienen un coeficiente de absorción capilar bajo.

Optimal thickness of various insulation materials for different temperature conditions and heat sources in terms of economic aspect

The article presents the methodology for calculating the optimal insulation thickness that is related to the quality of energy supply and fuel prices. Assuming that the total cost following renovation is the sum of the costs of heating and thermal upgrading, it was shown that when calculating the optimal insulation thickness, the thermal resistance of the outer walls should be taken into account. Such calculations, in addition to the characteristics of the heat source, should be carried out taking into account local weather conditions. The study presents the results of such calculations for the building heated with gas and the air-source heat pump. The results of the investigations are referred to the mean climatic conditions recorded in the last 10 years. It was found that for thermal upgrading with the use of foamed polystyrene having the optimum thickness, total investment costs are almost the same, regardless of polystyrene thermal properties. The same also refers to energy costs. The article also provides sample calculations for plaster, the main ingredient of which is perlite. In the case of internal thermal upgrading of the historic buildings, such isolation is recommended in order to prevent moisture problems inside the envelope.

DNA metabarcoding to assess indoor fungal communities: Electrostatic dust collectors and Illumina sequencing

DNA metabarcoding is increasingly being used to characterize the microbiological composition of both the indoor and outdoor environments of dwellings. Our study aimed to evaluate metabarcoding and bioinformatic analysis resulting from calibrated samples and samples collected by an electrostatic dust collector (EDC) in dwellings with no moisture problems. Thus, the fungal communities of 14 dwellings (eastern France, Franche-Comté region) were analyzed by Illumina MiSeq technology after amplification of the ITS2 region.Using the standard samples of 11 species of yeasts and molds allowed us to validate the Operational taxonomic units (OTU) assignment. These calibrated samples also showed a low amplification bias, a low rate of sequencing errors and the semi-quantitative nature of the technique.Only one species from the calibrated samples (Lichtheimia corymbifera) was less amplified probably due to the presence of two mismatches in its3 primer.EDC analysis identified 3594OTU with 75% of reads corresponding to 30 genera. The main genera are those usually found by culture techniques (Penicillium, Aspergillus and Cladosporium), but findings also indicate others less commonly isolated in culture such as Epicoccum, the fourth detected genus in our study. The type of heating systems was correlated with fungal diversity. We found less diversity in the dwellings with wood heating and larger quantities of Epicoccum nigrum verified by qPCR.DNA metabarcoding analysis applied to EDC seems promising. However, we think that it must be used along with qPCR, to obtain a more global view of microbial ecology and relative quantification of species of interest within communities.

Fungal monitoring of the indoor air of the Museo de La Plata Herbarium, Argentina

BackgroundBiological agents, such as fungal spores in the air in places where scientific collections are stored, can attack and deteriorate them. AimsThe aim of this study was to gather information on the indoor air quality of the Herbarium of Vascular Plants of the Museo de Ciencias Naturales de La Plata, Argentina, in relation to fungal propagules and inert particles. MethodsThis study was made using a volumetric system and two complementary sampling methods: (1) a non-viable method for direct evaluation, and (2) a viable method by culture for viable fungal propagules. ResultsThe non-viable method led to ten spore morphotypes being found from related fungal sources. A total of 4401.88spores/m3 and 32135.18 inert suspended particles/m3 were recorded. The viable method led to the finding of nine fungal taxa as viable spores that mostly belonged to anamorphic forms of Ascomycota, although the pigmented yeast Rhodotorula F.C. Harrison (Basidiomycota) was also found. A total count of 40,500fungal CFU/m3 air was estimated for all the sites sampled. ConclusionsBoth the non-viable and viable sampling methods were necessary to monitor the bio-aerosol load in the La Plata Herbarium. The indoor air of this institution seems to be reasonably adequate for the conservation of vascular plants due to the low indoor/outdoor index, low concentrations of air spores, and/or lack of indicators of moisture problems.

Toxicity of airborne dust as an indicator of moisture problems in school buildings

Moisture-damaged indoor environments are thought to increase the toxicity of indoor air particulate matter (PM), indicating that a toxicological assay could be used as a method for recognizing buildings with indoor air problems. We aimed to test if our approach of analyzing the toxicity of actively collected indoor air PM in vitro differentiates moisture-damaged from non-damaged school buildings. We collected active air samples with NIOSH Bioaerosol Cyclone Samplers from moisture-damaged (index) and non-damaged (reference) school buildings (4 + 4). The teachers and pupils of the schools were administered a symptom questionnaire. Five samples of two size fractions [Stage 1 (>1.9 μm) and Stage 2 (1–1.9 μm)] were collected from each school. Mouse RAW264.7 macrophages were exposed to the collected PM for 24 h and subsequently analyzed for changes in cell metabolic activity, production of nitric oxide (NO), tumor necrosis factor (TNF)-α and interleukin (IL)-6. The teachers working in the moisture-damaged schools reported respiratory symptoms such as cough (p = 0.01) and shortness of breath (p = 0.01) more often than teachers from reference schools. Toxicity of the PM sample as such did not differentiate index from reference building,s but the toxicity adjusted for the amount of the particles tended to be higher in moisture-damaged schools. Further development of the method will require identification of other confounding factors in addition to the necessity to adjust for differences in particle counts between samples.

Extent of moisture and mould damage in structures of public buildings

The study concentrated on the extent of moisture and mould damage in different structures in 25 public buildings in Finland. Users of all the buildings had health symptoms suspected to be the result of moisture and mould damage, which is why moisture performance assessments had been performed. The assessment reports on each building were available as research material. The reports indicated that the examined buildings suffered from multiple moisture and mould problems in several different structures. On average, however, a relatively small proportion of the total number of structures had suffered damage. On the basis of the research material, damage was most extensive in walls in soil contact (16.3%) and base floor structures (12.5%). The lowest damage rates were found in partition walls (2.4%), external walls (2.6%) and intermediate floors (2.5%). The results of the study underline the importance of thorough moisture performance assessments to ensure that all point-sized moisture and mould damage is detected.

Air Channel Function For Solving Moisture Problems In Buildings

The purpose of the research is to find adequate solution against rising damp in historical buildings. The improvement in this case is the use of ventilated air channels. A special group of historical buildings are churches because they do not use routines as for example museums, galleries.We designed 4 differently constructed ventilated air channels. These are: open or closed, with overpressure and underpressure. As a verification we use a relevance to these constructions which we simulated in software Ansys CFX the air flow of channels. We modelled the equal segments of the channels.The best solution of these constructions are the ventilated air channels with underpressure system. In this solution we measured the highest values of air velocity. Nevertheless this solution is not an aesthetic form of construction, because the pipes are set on the facade. But these pipe are put inside the drainage pipe.This research should offer the solution for architects against problems of rising damp in historical buildings. To find the right solution is necessary to research every case. The aim of the research is to prepare the design process of the ventilated air channels for the architects without the simulation of every building, cross section or geometry of the construction.

Effect of wetting time in the sorption and in the thermal conductivity of the most commonly used structural materials

During the thermal assessment of buildings, proper understanding and knowledge of the thermal behavior of the materials is required. Certain indoor and outdoor conditions can cause moisture transfer and could change the thermal properties of buildings (e.g. thermal conductivity, resistance, thermal diffusivity, specific heat capacity, etc.). In this technical note, a research report can be found on the measured thermal conductivity after drying and wetting the samples. For the measurements, we used a dry-heat laboratory oven (Venticell 111) apparatus to dry the samples and a climatic chamber (Climacell 111) to wet the materials in order to get the values. By applying these two chambers, we were able to reach the moisture content of different humidity levels and create the kinetic wetting curves for each sample. To measure the thermal conductivity, a heat flow meter type Holometrix 2000 was used. During the measurements, five different types of materials were used (solid brick, lightweight and foam concrete, plasterboard, corkboard). In order to reach acceptable accuracy, three measurement series were carried out on the samples at each wetting times. During one series, the thermal conductivity was measured 10 times, and the average of the 13 thermal conductivity results gave the final value. Moreover, from the measurement results, new equations and functions were created to show the relationship between the thermal conductivity and the moisture content of the materials. Our results showed that after wetting the samples in a climatic chamber at 293 K and at 90% relative humidity, the kinetic function (time dependence) of adsorbed water increased in the cases of all the materials used; however, thermal conductivity only increased considerably in the cases of the two different types of concrete and of the plasterboard. Practical application: The role of insulation materials in the building energy and moisture balance is more significant compared to the other materials of the building structures. The high moisture load will require the change of the thermal parameters of the materials. Moisture is a common cause of building degradation. In fact, much of what we know about applied building science today originates from early work investigating moisture impact on buildings, while the severity of moisture problems varies greatly depending on climate. These estimations based on the laboratory measurements of these values of the insulating materials are very important either for the manufacturers or the contractors, planners, and designers.

Hygrothermal performance improvement of the Korean wood frame walls using macro-packed phase change materials (MPPCM)

The application of phase change materials (PCM) in various fields is difficult due to their phase instability. To solve these problems, PCM requires shape stabilization. The macro-packed PCM (MPPCM) was suggested and prepared as a method to increase the content of the PCM. In Korea, hot and humid weather conditions in summer, exacerbated by indoor activities, are the major factors of moisture problems. Therefore, the hygrothermal behavior of building materials must be carefully considered to reduce the risk of condensation, reduce the mold growth potential, and enhance the comfort of the indoor environment. In this study, a macro-packed PCM (MPPCM) containing n-octadecane was prepared. The thermal properties of the MPPCM were characterized using a TCi thermal conductivity analyzer and a differential scanning calorimeter (DSC). Also, the hygrothermal performance of building components was evaluated using the WUFI (Wäme und Feuchte instationär) program; these components were wood-frame structures applied the MPPCM. As a result, the phase transitions of n-octadecane occurred at 29.76°C during heating, and their latent heats were 256.5J/g. The thermal conductivity of the MPPCM was three times higher than that of the pure PCM. The hygrothermal performance of the wood-frame structures applied the MPPCM, which replaced the use of the vapor retarder, is improved. Also, it is possible to solve the problems of mold growth risk using the prepared MPPCM.

СЕРЕДОВИЩНІ ФАКТОРИ РИЗИКУ СТЕНОЗУЮЧОГО ЛАРИНГОТРАХЕЇТУ В ДІТЕЙ.

Вивчено зв’язок між стенозуючим ларинготрахеїтом (СЛТ) у дітей і такими екзогенними факторами, як тютюновий дим, скупченість у житлових приміщеннях, вогкість у квартирі, наявність домашніх тварин, несприятливий психологічний клімат у сім’ї. Встановлено, що в дітей зі СЛТ значно частіше, ніж у контрольній групі, спостерігались випадки проживання в умовах скупченості в житлових приміщеннях і несприятливого психологічного клімату в сім’ї. Відсоток тих, хто проживав у сім’ях, де курять і, зокрема, де курить мати, серед дітей з 1–3 епізодами СЛТ був суттєво більшим, ніж серед дітей контрольної групи. Не виявлено значущої різниці між дітьми з рецидивним СЛТ (4 і більше епізодів захворювання) і дітьми контрольної групи щодо пасивного куріння. Дещо частіше, ніж у контрольній групі, серед дітей зі СЛТ траплялись випадки проживання у квартирах, де є вогкість (р<0,1). Не виявлено суттєвої різниці між дітьми зі СЛТ і дітьми контрольної групи стосовно наявності домашніх тварин.

Robust moisture reference year methodology for hygrothermal simulations

Hygrothermal models allow designers to evaluate the hygrothermal performance of building envelopes. A key question in hygrothermal modeling however remains in the proper selection of representative exterior moisture conditions, i.e. a moisture reference year. A Climatic Index combining wind-driven rain load and potential evaporation is developed allowing considering the effect of climatic variability on the performance of the building envelope. The proposed Climatic Index combines thus both the wetting load and evaporation potential. This index is suitable for the evaluation of the level of moisture damage risk of wall assemblies where typical moisture problems are mainly caused by rainwater uptake or ingress.The Climatic Index is determined for four cities in Switzerland. The hygrothermal performance of the assemblies is simulated and evaluated using a hygrothermal indicator, called the RHT Index. A clear correlation between Climatic Index and RHT Index is found. However, the moisture reference year selected based solely on a 10% level criterion of the Climatic Index may not correspond to the year with the most significant moisture damage risk. Therefore, a new procedure is proposed which combines a first selection of three years around the 10% level criterion, followed by a careful comparison of these years based on hygrothermal simulations and selection of the year with the largest RHT Index as moisture reference year. The combination of Climatic Index and RHT Index from hygrothermal simulations allows for the selection of moisture reference years that are around the 10% level, but excluding the ambiguity.

Energy Remediation Combining Insulation Materials Based on Calcium Silicate and Expanded Polymers

Energy rehabilitation of buildings using airtight insulating materials based on expanded polystyrene is often accompanied by the formation of moisture problems in the enclosure wall footing. Moisture progress in the rehabilitated structure is simulated using modern moisture transient models in Delphin software. Combinations of the developed plate thermal insulating materials based on calcium silicate and the conventional thermal insulation panels based on expanded polymer have been designed to address the moisture problems. This article describes the function of this solution during the reconstruction of a house built from full clay bricks with malfunctioning waterproofing in the lower house construction.

Respiratory Symptoms and Infections in Children and Employees at a Water-Damaged Kindergarten

Objectives: Several studies have shown an increased risk of infections and respiratory symptoms among people exposed to molds. Here, we report the morbidity of children and staff exposed to several toxic molds at a kindergarten. Methods: Prevalence of symptoms and the incidence of infections were followed up and compared between children and staff exposed in a day-care center affected by mold and those in a reference day-care center. At both day-care centers, parents (mostly mothers) filled out a questionnaire. Staff members with more severe symptoms were examined at the Clinic for Indoor Air Health Problems of the Skin and Allergy Hospital, Helsinki University Hospital. Results: Children and staff exposed to mold had more frequent symptoms and illnesses such as hoarseness, bronchitis than the nonexposed reference group. Symptoms in the exposed group were reduced following remedial building work and the avoidance of exposure. In addition, the acute care visits of the children to the local health care center were less frequent after remediation. One of the employees of a water-damaged kindergarten was diagnosed with allergic alveolitis and asthma, one had epipharyngitis, and two had mixed cell inflammation of the eye. Conclusions: Our study supports the results in which moisture and mold problems have been noted to increase disease rates of children and staff in day-care facilities. The study also suggest that detrimental health effects can be diminished by decreasing or stopping the exposure.