Crawl Space Research Articles

Infiltration of Mould from Crawl Space under the Prefabricated Bathroom

The indoor mould concentration depends not only on the outdoor mould source but also on the indoor mould source. The mould source is not only on the interior surface but also in the concealed spaces: a crawl space, a beam space, a wall cavity etc. Most detached houses in Japan have crawl spaces under the first floor. The humidity is high from spring to autumn in crawl spaces. Therefore the concentration of mould spore is very high in most crawl spaces. Prefabricated bathrooms called “bath-units” are installed in most Japanese houses. The authors showed in the previous studies that there are infiltration routes between bath-units and walls that the routes may lead chemical compounds from crawl space to indoor space. In this study, the influence of mould infiltration from crawl space upon indoor mould concentration is investigated using a test house which consists of a lavatory and a bathroom. The structure of the house is wooden post-and-beam. The house is airtight and insulated according to the latest building code for save energy. The mould concentrations were measured in the crawl space and the indoor spaces continuously using a mould multi-sampling system with a pump, valves and impingers. Before the measurements, the indoor mould concentration was made low using an air cleaner. The air flow rates were measured using tracer gases. After the exhaust fan was switched on, the mould concentration increased. The number of infiltrated mould was calculated using air flow rates and mould concentrations. The results showed that mould infiltration ratio may be one of the important indicators of indoor air quality.

Numerical Experiments on Indoor Air Quality Considering Infiltration of Mould from Crawl Space

How the air quality of crawl space influences the indoor air quality is investigated using a simulation program “Fresh 2010”, air leakage network models, and the measurement results on the mould concentrations in crawl spaces of detached houses. The annual changes of indoor mould concentrations were calculated using building models (a common wooden post-and-beam structure, improved wooden post-and-beam structure, wooden stud structure). In every structure, the concentrations in the case of exhaust ventilation system are higher than those of exhaust and supply ventilation system. The results show that it is necessary to control the air quality of crawl spaces and the infiltration from crawl spaces in order to keep indoor air quality good.

Improving Housing Conditions from the Crawl Space up with a Monitoring and Control System

Housing issues constitute a growing research area due to changes of building features and the use of technologically advanced material and devices in homes. Thus, housing-related research needs to be conducted in order to improve the living conditions in houses. This research explored the interactions of temperature and relative humidity in three contiguous housing environments (indoor, outdoor, and crawl spaces) to analyze and evaluate common housing issues. To achieve this goal, the design, development, and verification of a Housing Elements Research Chamber (HERC) by means of a monitoring and control system was tested. The monitoring and control system used sensors to continuously monitor temperature and relative humidity under different conditions. This study used the HERC to simulate housing conditions within the crawl space in order to determine the appropriateness of using different moisture-removal methods to improve housing conditions. Results showed that the use of temperature and relative humidity sensors as part of a monitoring and control system provided adequate tools to study the climate interactions between different environments in a house. Furthermore, findings indicated that the use of multiple moisture-removal methods is a desired solution to improve housing conditions.

Controlled relative humidity in crawl spaces: a new treatment methodology

PurposeCrawl space ventilation became essential to avoid moisture damage. Historical houses with wood floor and crawl spaces unventilated correctly often face problems of biological degradation. This paper seeks to address these issues.Design/methodology/approachIn this work a case study of the Egas Moniz museum house, in Estarreja, Portugal, with different building pathologies, such as biological degradation and development of micro‐organisms and fungi, is presented. An experimental campaign was carried out with continuous monitoring of the relative humidity and temperature, to validate the real climatic conditions in the crawl spaces. Additionally, the authors analyse the treatment technologies used in the past and the characteristics of the rehabilitation solutions in order to control the hygrothermal behaviour. Simultaneously, numerical simulation was done using the software tool WUFI‐2D to simulate the hygrothermal building behaviour and a sensitivity study of parameters used was done.FindingsThe in‐situ experimental results showed that high values of relative humidity imply biological degradation of the wood floor and the numerical and analytical models used showed the same tendency. The numerical results showed the importance of crawl spaces with a good ventilation to avoid mould growth and, also, suggested that controlled mechanical ventilation is preferable to strongly continuous mechanical ventilation in this type of spaces. The experimental study shows that the continuous functioning of a ventilation system may lead to the occurrence of interior condensation, so a hygro‐regulated system is thus essential to control unwanted condensation, with an appropriate functioning criterion.Practical implicationsIn accordance with the numerical and experimental results, the authors proceeded to the implementation of a hygro‐regulated system to ventilate the crawl spaces of the Egas Moniz museum house.Originality/valueThis paper presents a new proposed intervention methodology, in crawl spaces, to avoid mould growth, based on an extraction controlled by a hygro‐regulated ventilator.

Reading in the Crawl Space: A Study of an Urban School's Literacy-Focused Community of Practice

Background/Context The pressure to understand “what works” to advance adolescents’ reading development has increased as the Common Core State Standards’ call for youth to grapple with a range of complex texts. While we have learned more about promising reading programs and interventions for adolescent students in schools, few programs have had a demonstrable impact on middle and high school students’ reading achievement. As a result, categorical reading underperformance among youth persists in schools nationwide and is worse in urban schools. Instead of examining the effects of a reading program in isolation, we may need to turn our attention to understand how those programs are lived and enacted within the contexts of their school cultures. Purpose and Research Questions This study depicts one urban school's efforts to support its middle and high school students in reading. Two research questions guided this study: 1. What are the current practices designed to provide a sociocultural context conducive to growth in reading skills at Grant Street Secondary School? 2. How do various organizational members (i.e., students and staff) perceive and experience these practices at Grant Street Secondary School? Though a range of factors influenced students’ reading at the school, this paper provides an in-depth portrayal of another instructional component — independent reading — that emerged in my analysis as vital to the way students and staff oriented themselves around literacy. Research Design Because the theoretical frame for this study assumes that literacy is social and situated, my research design reflected an effort to describe interactions related to reading, the domains where reading activity circulated, and perceptions of those interactions. As such, I drew upon three sources of qualitative data: interviews from staff and students, ethnographic observational data, and documents. These three sources of qualitative data enabled me to describe the literacy activities at the school and locate them in the larger school organizational and cultural processes. Conclusions and Recommendations This study suggests that students may benefit from daily, sustained time for independent reading time that is instructional. This study also suggests that coordinated efforts across school staff may ensure youth's positive interactions with texts. This study also holds implications for school-based research focused on disciplinary literacy. Ultimately, this research reconceptualizes our understanding of effective instructional practices for adolescents, emphasizing a multidimensional approach that highlights the role of reading as a social activity.

Spatiotemporal variability of tetrachloroethylene in residential indoor air due to vapor intrusion: a longitudinal, community-based study

The migration of volatile contaminants from groundwater and soil into indoor air is a potential health threat at thousands of contaminated sites across the country. This phenomenon, known as vapor intrusion, is characterized by spatial and temporal heterogeneity. This study examined short-term fluctuations in concentrations of tetrachloroethylene (PCE) in the indoor air of residential homes due to vapor intrusion in a community in San Antonio, Texas, that sits atop an extensive, shallow plume of contaminated groundwater. Using a community-based design, we removed potential indoor sources of PCE and then collected twelve 3-day passive indoor air samples in each of the 20 homes. Results demonstrated a one-order-of-magnitude variability in concentration across both space and time among the study homes, although all measured concentrations were below risk-based screening levels. We found that within any given home, indoor concentrations increase with the magnitude of the barometric pressure drop (P=0.048) and humidity (P<0.001), while concentrations decrease as wind speed increases (P<0.001) and also during winter (P=0.001). In a second analysis to examine sources of spatial variability, we found that indoor air PCE concentrations between homes increase with groundwater concentration (P=0.030) and a slab-on-grade (as compared with a crawl space) foundation (P=0.028), whereas concentrations decrease in homes without air conditioners (P=0.015). This study offers insights into the drivers of temporal and spatial variability in vapor intrusion that can inform decisions regarding monitoring and exposure assessment at affected sites.

Validation of critical moisture conditions for mould growth on building materials

Materials that are stored or used in damp conditions may be subject to mould growth. However, all materials are not equally susceptible; for each specific material, there is a critical moisture level for mould growth. If this is exceeded, there is a risk that mould fungi will develop on the material. This level can be determined in accelerated laboratory tests, at constant temperatures and relative humidity (RH) favourable to mould growth. Within a building however, these parameters are expected to vary from one part of the construction to another, and are seldom constant; there is fluctuation in temperature and RH due to seasonal or shorter-term variations. In this study, test pieces of the same materials tested in a laboratory environment were placed in three outdoor ventilated crawl spaces and three outdoor ventilated attics, where the temperature and RH varied, and mould growth on the test pieces was studied over 2.5 years. Material-specific mould growth curves were produced based on critical moisture levels, as determined in laboratory experiments under constant temperature and RH. When the actual conditions of RH and temperature exceeded these curves, there was mould growth on the test pieces if the time was sufficiently long. The conclusion from the study is that although conditions in laboratory studies are simplified and accelerated, the results serve well to indicate mould growth within a building construction.

Hygrothermal simulations of foundations: Part 1: Soil material properties

Deep basements, crawl spaces and slab on grade are typical foundations in residential buildings in North America. The foundation of a house is a somewhat invisible and at sometimes ignored component of the building. Appropriate foundation design and construction practice must not only include thermal performance, but also design for a durable and safe hygrothermal performance. A hygrothermal simulation tool can be used to evaluate and predict the hygrothermal behavior of an insulated foundation constructions, in cooperation with the surrounding soil. Though, further development of the tool might first be needed and validated to fulfill the prerequisites. Transient hygrothermal simulation tools have existed in Building Science for more than 20 years, but are mainly used for building envelope simulation above ground. A lot of knowledge already exists in Soil Science concerning the variation of the soil material properties in relation to soil texture, moisture content etc. However, Soil Science uses these properties for other purpose and with different modeling approaches, hence a conversion is needed. This paper studies the existing knowledge of soil properties, converted to apply for simulation in Building Science. Further, the soil properties are implemented in a transient hygrothermal simulation tool, studying the applicability for modeling soil temperature and moisture flow. Finally the results are compared with measurement and followed by a discussion of further investigations and development needed.

Poster - Thur Eve - 09: Novel radiation safety challenges of a brachytherapy redevelopment at the Credit Valley Hospital.

Carlo Fidani Peel Regional Cancer Center at the Credit Valley Site of the Credit Valley Hospital and Trillium Health Center is currently undergoing a redevelopment to build a brachytherapy suite and associated areas with a projected start date of April 2013. The new brachytherapy suite will be located in the PRCC, and is a redevelopment of office area into clinical space. The workload for the full brachytherapy program is expected to be 20 patients per week, in cervix, prostate, skin, lung and other sites. There were challenges for shielding due services in the slab to the renal clinic located above the redevelopment area. The presence of over 30 voids in the slab and upper walls made the solution to add shielding to the underside of the current slab unsuitable. To overcome this, a second ceiling built below the slab to allow for an uninterrupted shielding for the brachytherapy suite. The additional ceiling allows for a crawl space between slab and shielding allowing for servicing if needed for the drains from the renal clinic. The appropriate finalized shielding design is 69mm of lead brick supported by steel plate and steel beams. Final shielding for the walls is 690mm of concrete that allows public access to all hallways around the facility. The final design for the new brachytherapy site at the PRCC all services for the room are located within the shielding and all services for areas outside the room are located outside the shielding.

Sensitivity analysis on parameters and processes affecting vapor intrusion risk

A one-dimensional numerical model was developed and used to identify the key processes controlling vapor intrusion risks by means of a sensitivity analysis. The model simulates the fate of a dissolved volatile organic compound present below the ventilated crawl space of a house. In contrast to the vast majority of previous studies, this model accounts for vertical variation of soil water saturation and includes aerobic biodegradation. The attenuation factor (ratio between concentration in the crawl space and source concentration) and the characteristic time to approach maximum concentrations were calculated and compared for a variety of scenarios. These concepts allow an understanding of controlling mechanisms and aid in the identification of critical parameters to be collected for field situations. The relative distance of the source to the nearest gas-filled pores of the unsaturated zone is the most critical parameter because diffusive contaminant transport is significantly slower in water-filled pores than in gas-filled pores. Therefore, attenuation factors decrease and characteristic times increase with increasing relative distance of the contaminant dissolved source to the nearest gas diffusion front. Aerobic biodegradation may decrease the attenuation factor by up to three orders of magnitude. Moreover, the occurrence of water table oscillations is of importance. Dynamic processes leading to a retreating water table increase the attenuation factor by two orders of magnitude because of the enhanced gas phase diffusion.

内部建材の化学物質放散が室内空気質に与える影響

The infiltration ratios of pollutants from concealed spaces to indoor spaces were measured using a tracer gas method in a structure model and detached houses. The results are the followings:1. The infiltration ratios from beam spaces were very high and those from crawl spaces and truss spaces were not low.2. The infiltration ratios became higher when indoor spaces were decompressed by exhaust ventilation systems.3. It is necessary to prevent the infiltration of pollutants from concealed spaces to indoor spaces and to keep air quality of concealed spaces.

Full-scale study of a building equipped with a multi-layer rack latent heat thermal energy storage system

Phase change material has been installed as a latent heat thermal energy storage system coupled with the ventilation system in an office building located in Lyon, France. The main purpose of this study is to determine if the phase change material system can guarantee the summer comfort of the occupants without energy-consuming cooling devices. Sensors have been set up, and the collected data are monitored to study the thermal behavior of the building and the phase change material. Numerical simulations complete the work to study and compare the building behavior without phase change material. The temperature charts in each office show that the thermal comfort of the workers is acceptable in winter and summer. Numerical results show a difference of temperature in offices due to the ventilation through the crawl space equipped with the phase change material multi-layer racks. The temperature in the crawl space varies between 12°C and 25°C (53.6°F and 77°F) all through the year. It is then possible to conclude that the new ventilation system is efficient for the precooling or preheating of air.

Crawl spaces as reservoirs for transmission of mold to the livable part of the home environment

Recent studies suggest that exposure to mold in damp buildings is an important environmental risk factor for childhood respiratory illness. One potential source of a damp home, is crawl space construction. A poorly constructed crawl space not only presents the possibility of contributing to a 'damp' home but can also become a reservoir for fungal growth. Fungal levels in the livable indoor environment have been characterized in other studies, but little has been done to assess the potential for mold growth in the crawl space. This study examines the potential for mold growth and subsequent transmission from the crawl space into the home environment. In this study, we assessed mold contamination levels within crawl spaces from 238 study homes in North Carolina. We determined whether air leakage from the heating, ventilation, and air conditioning (HVAC) system and associated ductwork, transmitted viable mold spores from the crawl space into the living spaces within the home. The results indicate that 19% of the homes demonstrated transmission of mold spores from the crawl space into the indoor environment, 45% of the homes displayed no transmission, and 36% of the homes were indeterminate. The results support the hypothesis that the HVAC system can serve as a conduit for the transmission of mold spores from the crawl space to the indoor environment of a home. This transmission likely affects children's health, given the significant amount of time they spend in the home environment. For low-income families, the HVAC system may contribute an additional source of childhood exposure and highlights the importance of the assessment of indoor environmental hazards.

Grandma's Four Stories

Grandma's Four Stories Lyzette Wanzer (bio) The house with the porch, the wooden swing, with the garden, the alley cats, with the woods, the hidden lake, with the fruit trees, the aunts, uncles, greats, blood cousins, convenience cousins, from points north and south, in the green kitchen and earthy den, with the attic bedroom, the dusty basement, with the crawl spaces, the hidden panels, with the tunnel, now sealed, part of the Underground Rail. She so spun her fairy tales without sugar coating, not even for a preschooler, I got to imagining a slave collapsed, red bandana over her hair, tattered skirt, single-sandaled, weary, frightened, glad to have reached refuge. Three yellowed pine needles spanned the part in her hair as she led me through soaring boles, damp wind churning the clouds' meringue faces, prickling our noses, top notes of spring rain. Past the casual buzz of bumblebees, whipping motor of hummingbird wings, through the creek's running light, cupping apples in our damp grainy palms, skittering from one rock to the next like a pair of dusky water spiders, breeze freighted with seaplane fumes, a here-and-there square of muted sunshine poking through, queue of cats trailing after us. No friends of mine, but they knew her and I had to share. We all left firm, fine prints in banked sand. A stroke swooped down on the wings of the quietest bird you ever didn't see. After that. Underground stories, woodland treks, gatherings in the presence of the ancestral, nixed. I was still shapeless, all elbows, knees, beaded braids, roller-skate skinny, and very much interested in being a boy. Was told she lost the house, just couldn't fathom how anyone could lose a house that huge. Was told she lost her left arm and leg, yet both were still there. The holiday hearth migrated with her to the city, to Murray Hill, to the East Side one-bedroom with dueling TVs, Planet of the Apes vs. King Kong, folks digging their turkey, stuffing, their Smithfield, cranberry sauce, their collards, cobbler, their kale, salsa, their pig's feet, sugar pie on the balcony, the sofa, in the kitchen, the bathroom, in the foyer, the closets, and for the under-18s, the outside hallway. [End Page 74] Lyzette Wanzer Lyzette Wanzer has published in a number of periodicals, including Literary Paritantra, Pacific Review, Specs, Tampa Review, Journal of Experimental Fiction, Iris, and Pacific Review. Copyright © 2011 The Johns Hopkins University Press

Performance Prediction Method in the Early Design Stage for Outdoor Ventilated Crawl Spaces Based on Artificial Neural Networks

The purpose of this article is to explore the possibility of using a tool based on artificial intelligence and real-life data. The aim is to develop and analyze one artificial intelligence method for one design part of a single-family house. Real-life data from documented experiences have been used as training data to develop a neural network to predict the performance of a specified design part, in this case, the outdoor ventilated crawl space. The results of this study indicate that this is an approach that could usefully be developed and investigated further. The tool managed to predict smell 100%, mold 76%, and rot 92% correctly.

Critical conditions for onset of mould growth under varying climate conditions

A performance-based service life design format based on climatic exposure on one hand and “resistance” of materials against mould growth on the other hand, is presented in this paper. A limit state for onset of mould growth is defined as the occurrence of traces of mould observed by microscopy. A dose–response model is proposed by which onset of mould growth can be predicted for an arbitrary climate history of combined relative humidity ϕ and temperature T. The model is calibrated and verified against a comprehensive set of experimental data published by Viitanen et al. [Viitanen H, Ritschkoff A-C. Mould growth in pine and spruce sapwood in relation to air humidity and temperature. Uppsala: Swedish University of Agricultural Sciences, Department of Forest Products; 1991. Report No. 221, 49 p.; Viitanen H. Modelling the time factor in the development of mould fungi – effect of critical humidity and temperature conditions in pine and spruce sapwood. Holzforschung 1997;51(1):6–14; Viitanen H. Modelling the time factor in the development of brown rot decay in pine and spruce sapwood – the effect of critical humidity and temperature conditions. Holzforschung 1997;51(2):99–106; Viitanen H, Bjurman J. Mould growth on wood under fluctuating humidity conditions. Material und Organismen 1995;29(1):27–46] describing mould development on spruce and pine sapwood as a function of climatic exposure. The model is applied to predict time to onset of mould growth under natural outdoor climate (under shelter) as well as mould development in building attics and in crawl space foundations. The predicted response shows reasonable agreement with experimental observations and proven experience, although biological processes of this type display great variability. The results show that a generally applicable, quantitative model can be used as a powerful tool for moisture safe design in practice. The model is designed to facilitate continuous improvement of prediction capability by further laboratory testing of various materials under specified climate conditions. In combination with currently available building physics software the model is suitable for moisture safe design of wood-based components in the building envelope.

ANALYTICAL STUDY ON THE HYGROTHERMAL BEHAVIOR IN CRAWL SPACES WITH INSULATION FOUNDATION WALL IN THE FIRST YEAR AFTER COMPLETION

The vertical edge insulation on foundation walls, the popular method for structures located in colder regions, is expected to spread across moderate and humid climate regions because of its insulation superiority in the hygrothermal environments found in crawl spaces. However, in the first year after completion of buildings, the hygrothermal condition in crawl spaces with insulation foundation wall tends to worsen, leading to condensation and heating load growth. We clarify the factors affecting the hygrothermal behavior in crawl spaces with insulation foundation wall and explore some possible improvements in these hygrothermal environments through simulating simultaneous heat and moisture transfer.

INVESTIGATION OF PRESSURE DIFFERENCE TO ASSESS HYGROTHERMAL BEHAVIOR OF WALL ASSEMBLIES WITH AIRFLOW

Several researches related to airflow within wood-frame wall assemblies have been conducted in order to assess their hygrothermal behavior. However there are very few reports which investigate boundary conditions such as pressure difference and/or leakage area to predict the airflow rate through wall cavities. This paper describes the pressure difference that causes the airflow for vertical direction within the wall assembly. The pressure difference between the crawl space and the attic on an actual wood frame house were measured in the winter season. Additionally effects of several factors, such as air-tightness of connections of the wall, outdoor wind velocity, and temperature difference between indoor and outdoor air, were experimentally investigated. The experimental results finally indicated that the pressure difference can be approximately predicted using the temperature difference between indoor and outdoor air when outdoor wind velocity is less than 1.5m/s.

Fine Print and Hidden Charges

Every one of my grandchildren has computer skills that exceed mine. My parents didn’t have television until I was a sophomore in college. I don’t facebook, twitter, or have a cell phone. I even fail to answer e-mails on a regular basis. One could correctly state that I’m technology challenged, but months ago I did have high speed Internet. At that time, access to the Internet didn’t tie up my telephone and downloading a manuscript took seconds rather than hours. The access to high speed Internet was lost simply because too few people in the area subscribed to the service, so the Internet provider couldn’t profit by their offering. We received a nice letter stating that the service would be discontinued and that there were several other providers for high speed Internet operating in our area. The letter even provided a list of potential providers plus telephone numbers. After a day of going through the list, only two of the companies were willing to offer service to our location. One offered service via satellite and the other via a cell phone connection. We decided to go with the satellite provider. After three phone calls and an hour discussion with Ted, we had established a price for the required equipment, a monthly service fee, and a date and time for the installation. Access to high speed Internet was just around the corner, until the installer called. The price for the installation was simply a basic price. If the installer had to climb a ladder, the fee went up $100.00, and it went up another $100.00 if he had to deal with a crawl space or string wires in the attic. Additionally, the dish couldn’t be mounted on the garage roof, so the required pole would cost even more. We decided that the hidden fees were too much and transferred our attention to service via a cell phone connection. The cell phone service offered a 30-day risk free trial. That sounded good, especially after the recent experience with the installer. The sign up required a deposit, a credit check, and a two-year contract. The salesman even checked with the company office to be certain that service was available at our house. I warned him that several other providers had suggested problems at our location, but was assured that we were within two miles of their tower and the service would be excellent. We signed up. After all the trial was risk free, that is, until we found that the service didn’t reach our computer. The company cancelled our two year contract and basically refunded our deposit—except for a $25.00 restocking fee (part of the fine print). About a month later I received a bill for one month’s service. I pointed out that the service never worked, but was shown that regardless of the quality, we had service for the several days we were trying to use the system and therefore owed for a month’s service. So much for risk-free. The fine print was worse than the hidden charges—at least the installer informed us of the potential hidden charges and allowed us to cancel the service without expecting a fee. I still don’t have high speed Internet, but I do have a list of two companies that will never receive future business from me. I feel that I was lied to, cheated, and stolen from. A reliance on hidden charges and fine print is no way to do business. Society appears to be drifting away from honesty and moving toward saying whatever the customer wants to hear. The political arena is filled with liars who say that they ‘‘mispoke’’, cheats who sell their influence under the door of contributions and provide ‘‘ear marks’’ that become the fine print in numerous bills. An automobile dealer quotes a price, then adds transportation and dealer M. R. Louthan (&) Box 623, Radford, VA 24143, USA e-mail: macfran61louthan@yahoo.com

Housing and allergens: A pooled analysis of nine US studies

Housing conditions can contribute to allergen exposures that are linked to asthma, but little is known about which of those conditions are most likely to predict high levels of allergens in settled house dust. We pooled allergen, housing condition, occupant behavior, demographic, and other data from nine asthma studies (n=950 homes in 6 US cities). Dust mite (Der f 1 or Der p 1), cockroach (Bla g 1 or Bla g 2), mouse (Mus m 1), cat (Fel d 1) and dog (Can f 1) allergens were measured in settled dust from kitchens or bedrooms, and concentrations were categorized according to previously published asthma symptom thresholds. We calculated odds ratios (OR) using logistic regression to identify those housing conditions and occupant behaviors that were associated with clinically significant allergen levels, after adjusting for numerous confounding variables. The adjusted results show that high cockroach allergen was associated with cracks or holes in walls (OR=2.1), high dust mite allergen was associated with mold odor (OR=2.5), housing built before 1951 (OR=2.1), and single-family home with slab on grade (OR=1.9); and mouse allergen was associated with rodent control or signs of rodents (OR=3.62) and inversely associated with presence of a cat (OR=0.20). Water leaks and below average housekeeping had unadjusted high odds ratios for high cockroach allergen. We have identified a number of housing conditions that are consistently associated with increased allergen dust concentrations. This study indicates that screening for housing-based asthma triggers should include presence of cats, dogs, cockroaches, or rodents; water leaks; mold or mold odor; holes or cracks in walls; and below average housekeeping. Single family houses that have basements or crawl spaces or are built before 1951 are also important predictors for increased allergens in housing.