Winds create forces on buildings, sometimes with disastrous results. Low-slope roofs are subjected to potentially high levels of suction pressure, especially when winds strike the corner of a building, creating vortices. Traditional methods of attaching roof membranes to substrates are prone to failure when the low pressure on the roof surface instigates a transfer of forces to the roof membrane. Existing pressure-equalized roof systems use the power of the wind to transmit low pressure to the space immediately beneath the roof membrane, pulling the membrane down to the roof surface. The object of this study is the design of a wind vent which, when coupled with a single-ply roof membrane in a complete roof assembly, will successfully equalize low pressure throughout the entire field of the roof. The proposed wind vent differs from existing equalizer valves in its use of the Bernoulli effect to create low pressure. Optimized for ease of manufacturing and installation, the vent is omni-directional and contains no moving parts. After the wind vent prototype is developed, future study will be required to determine the tributary area of each vent, the interaction with the insulation beneath the membrane, the response time of the system when subjected to dynamic wind loading, the effect on the vent of various weather conditions, and the permissible amount of infiltration into the roof system. Associated research will also investigate the benefits of incorporating the heat evacuating capacity of the pressure-equalizing roof vent system into a roof membrane containing an amorphous photovoltaic array. / Master of Science

abstract: The overall purpose of this investigation is to examine the differences between the Best Value Approach and Best Value Procurement, and to test if the Best Value Approach can be used for the successful delivery of roofing systems. Best Value Procurement has been run on delivering roofing services for many years. However, in the last three years, it was discovered that Best Value Procurement was not sustainable and filled with risk. To examine if the Best Value Approach can be used for the successful delivery of roofing systems, the researcher identified a client in need of a new 70,000 sq. ft. industrial roof installation at their facility in the Phoenix Metropolitan area. The client willingly agreed to test the Best Value Approach as the project delivery method. The results of the project were documented, and they show that the Best Value Approach can be successfully implemented on an industrial roofing project with high performance results. The Best Value Approach’s advantage over Best Value Procurement is it addresses risk using “level of expertise” and cost to select a vendor. This paper identifies the differences between the methodologies and shows how the Best Value Approach can be an optimal approach for other roofing projects. / Dissertation/Thesis / Masters Thesis Construction Management 2017

A novel strategy was used to assess the risk to health from exposure to polycyclic aromatic hydrocarbons (PAHs), an important class of chemical carcinogens, in workers in the paving and roofing industries using bitumen. The aim was to evaluate the risk of exposure to PAHs at three different stages: these were external exposure "external dose", internal exposure "internal dose" and biological effect "biologically effective dose". The approaches used for quantifying the risk at these stages were ambient monitoring, biological monitoring and biological effect monitoring, respectively. Ambient monitoring was carried out by personal air sampling and measurement of PAH-exposure. Excretion of thioethers (a non-selective biomarker) and 1-hydroxypyrene (a selective biomarker of exposure to pyrene) in urine were determined. Urinary d-glucaric acid, sister chromatid exchange in peripheral blood lymphocytes and micronuclei in exfoliated cells were use for biological effect monitoring. Seven groups of workers were studied. These were office workers, departmental staff and manual workers who were not occupationally exposed to PAHs and who were included as controls, and two groups of payers and roofers who were exposed to bitumen fumes during their work. The ambient monitoring program revealed that concentrations of PAHs in environmental air could be as high as those found in the payers' and roofers' occupational environments. The contribution of these background levels to the external dose of the pa yers and roofers was considerable. Payers and roofers were occupationally exposed to low levels of PAHs. The PAH profile in the personal air sample of the workers was different between the two industries. This was attributed to the presence of PAH-emission sources other than hot bitumen, such as vehicle exhaust. The concentration of naphthalene measured in air samples was a good indicator for identifying the existence of these sources. The quantitative evaluation of the carcinogenic risk inherent in the external dose using the 8 hour TWA concentration as a measuring stick did not seem to be effective due to the low "noise" levels of carcinogenic PAHs present. A semi-quantitative measure of the external exposure was suggested which appeared to be a better reflection of the carcinogenic risk. Urinary thioethers are not sensitive enough to be used as a nonselective biomarker of exposure to low levels of PAHs; however, urinary 1- hydroxypyrene was a good indicator of internal exposure to pyrene and therefore PAHs in bitumen fume. The relationship between 1-hydroxypyrene in urine and specific airborne PAH-exposure indices in the results of the payers, but not the roofers, suggested that the route of exposure in the latter is mainly dermal while that in the payers is more related to respiratory uptake. This observation, however, did not agree with the subjective occupational hygiene assessment where it was observed that the roofers were closer to the source of PAH-emissions due to the nature of their job and both groups did not use any respiratory or personal protective equipment. The measurement of urinary d-glucaric acid excretion suggested, but not strongly, that hepatic enzyme activity was induced in the occupationally PAH-exposed groups in comparison to controls and reflected the internal dose of pyrene or total PAHs. These observation; however, need further investigation. Micronuclei in exfoliated epithelial cells could not be measured in these populations as insufficient bladder epithelial cells were obtained for analysis. Sister chromatid exchange in peripheral blood lymphocytes of payers and roofers was significantly elevated in comparison to control and manual worker group. The group mean frequencies of SCE were significantly correlated with the external exposure to carcinogenic PAHs. This observation suggested that sister chromatid exchange is a very sensitive cytogenetic endpoint and is useful for evaluating the risk of exposure to low levels of carcinogenic PAHs. Risk assessment, such as the one conducted in this study, allows a quantitative estimation of risk associated with long-term exposure to moderate and low levels of airborne exposure to PAHs in bitumen fume. Knowledge of dose response relationship may allow a review of current Occupational Exposure Standards (OES) and Biological Exposure Limits, which are at present either unavailable or based on poor background scientific knowledge for most PAH compounds. In this study we have suggested an Occupational Exposure Limit for PAHs based on the sum of fourteen PAH-species.