Exterior Cladding Research Articles

Effect of Hygrothermal Aging on Hydrophobic Treatments Applied to Building Exterior Claddings

Hydrophobic materials are among the most commonly used coatings for building exterior cladding. In fact, these products are easily applied to an existing surface, significantly reduce water absorption and have a minimal impact on the aesthetic properties. On the other hand, although these products have a proven effectiveness, their long-term durability to weathering has not yet been systematically studied and completely understood. For these reasons, this study aims to correlate the effect of artificial aging on the moisture transport properties of hydrophobic treatments when applied on building exterior claddings. Three hydrophobic products (an SiO2-TiO2 nanostructured dispersion; a silane/oligomeric siloxane; and a siloxane) were applied on samples of limestone and of a cement-based mortar. The moisture transport properties (water absorption, drying, water vapor permeability) of untreated and treated specimens were characterized. Furthermore, the long-term durability of the specimens was evaluated by artificial aging, that is, hygrothermal cycles (freeze–thaw and hot–cold). All treatments have significant hydrophobic effectiveness and improve the long term-durability of the treated specimens. However, the results showed that the three hydrophobic products have different effectiveness and durability, with the SiO2-TiO2 nanostructured dispersion being the most durable treatment on limestone, and the siloxane the most suitable for cementitious mortar.

Geotechnical properties of Lower Eocene limestones, Sinn El-Kaddab Plateau, southwest of Aswan, Egypt

This study investigates physical and mechanical characteristics of Lower Eocene limestone exposed on the Sinn El-Kaddab Plateau, southwest of Aswan. The limestone successions belonging to the upper member of the Dungul Formation attain 120 m in the composite section of the area. Sedimentologically, these limestones are composed of three lithofacies; hemipelagic facies at base composed mainly of wackstone, followed upwards by shallow marine nummulitic packstone and grainstone, and middle ramp facies at top composed mainly of bioclastic grainstone. The average values of the investigated physical properties include true density (2.70 g/cm3), bulk density (2.40 g/cm3), apparent specific gravity (2.66 g/cm3), apparent porosity (10.32%), and water absorption (4.44%). The average investigated mechanical properties values include Schmidt rebound attains (27.46), maximum stress (27.82 N/mm3), and compressive strength (283.77 kg/cm2). Unconfined uniaxial compressive strength and abrasion impact values were derived mathematically from equilibrated curves using Schmidt rebound values. Both limestones of Naqb Dungul and Kalabsha localities are suitable for uses in construction and ornamental purposes as dimension stone such as in floor tiles, interior and exterior cladding, production of bricks and mosaics, and possible non-constructional uses include fillers and pigments. Low values of both abrasions impact value obtained results; unconfined compressive strength and confined compressive strength of the lower facies refer to unsuitability as wear abrasive or road aggregates.

Design, construction, and thermal performance evaluation of an innovative bio-based ventilated façade

The energy consumption of the construction sector and its overall environmental impact has greater potential for improvement than those of many other sectors. Most energy consumed throughout the lifecycle of a building is expended during its operation and maintenance, for which the building envelope plays an important role. This study reports on the design, construction, and thermal performance evaluation of a ventilated façade. The façade should be quickly assembled, disassembled, and stored in containers for easy onward transport. Such features comply with the Rules and Building Code of the Solar Decathlon Middle East 2018 and the relevant Eurocodes. The façade is constructed using bio-based materials in keeping with the principles of a circular economy. The exterior cladding consists of sanitary paper, grass, reeds, recycled textiles, drinking water treatment waste, bio-based polyester resin, and other materials. Temperature and the air velocity measurements recorded on the façade in Dubai showed that the façade had contributed to cool temperatures within the apartment, particularly during the hottest hours of the day. The façade is a promising option for climates with hot summers and mild winters as it contributes to reducing energy consumption and the environmental impact of building materials.

Performance assessment of BIPV/T double-skin façade for various climate zones in Australia: Effects on energy consumption

Being the interface between indoor and outdoor, building envelope significantly influences indoor heating and cooling loads and thus affects building energy consumption. This paper presents the results of numerical simulation for the performance prediction of building-integrated photovoltaic/thermal double-skin facade (BIPV/T-DSF). Different BIPV materials (amorphous silicon PV, dye-sensitized solar cell and Perovskite based solar cells) were considered as the exterior cladding of a North-facing facade of an office building located in Australia. The performance assessment involved the selection of three climates in Australia, represented by the cities of Darwin, Sydney and Canberra. The air cavity created between the outer skin and the inner one were alternatively assessed in the non-ventilated, naturally-ventilated and mechanically-ventilated modes of operation, while a full sensitivity analysis was performed in order to assess the influence of different design parameters, such as internal skin’s thermal transmittance, cavity depth, ventilation louvres’ opening ratio and cavity ventilation rate. By comparing the different operational modes and BIPV technologies, it was found that naturally-ventilated DSF integrating the Perovskite-based solar cell could be the optimal configuration achieving the highest savings. Total annual energy savings of 34.1%, 86% and 106% annual were reached respectively in Darwin, Sydney and Canberra, in comparison to conventional technologies. In addition, this façade technology could further reduce the building’s heating and cooling loads by harvesting thermal energy generated within the air cavity. The study finally demonstrated that the harvested electrical and thermal energy from the façade could cover a significant share of building’s energy consumption.

The influence of hydrophobic protection on building exterior claddings

This study presents the results of an experimental campaign with the aim of investigating the hydrophobic protection of three substrates (stone, render, and external thermal insulation composite system—ETICS) with the application of three hydrophobic products: silicon and titanium dioxides-based nanostructured dispersion (HNST); a silane/oligomeric siloxane (HSila/Silox); and a siloxane (HSilox). To determine the effectiveness of the hydrophobic treatments, specimens of the untreated and treated wall coatings were characterized with different laboratory tests. The results showed that all products introduced significant improvements in the hydric properties of the substrates, leading to lower capillary water absorption (98%), water permeability with Karsten pipes (99%), drying index (39%), and higher water repellency assessed through the contact angle (283%). The application of hydrophobic materials also had a negative effect, leading to up to a 227% increase in resistance to water vapor diffusion. Among the assessed wall coatings, the rendering mortar appears to have the best initial performance after the application of all the types of hydrophobic materials tested. In general, the hydrophobic product HSilox was proved to be the most suitable for rendering mortars, while HNST was more appropriate for stone substrates.

Evaluation of Classical Operators and Fuzzy Logic Algorithms for Edge Detection of Panels at Exterior Cladding of Buildings

The automated process of construction defect detection using non-contact methods provides vital information for quality control and updating building information modelling. The external cladding in modular construction should be regularly controlled in terms of the quality of panels and proper installation because its appearance is very important for clients. However, there are limited computational methods for examining the installation issues of external cladding remotely in an automated manner. These issues could be the incorrect sitting of a panel, unequal joints in an elevation, scratches or cracks on the face of a panel or dimensions of different elements of external cladding. This paper aims to present seven algorithms to detect panel edges and statistically compare their performance through application on two scenarios of buildings in construction sites. Two different scenarios are selected, where the building façades are available to the public, and a sample of 100 images is taken using a state-of-the-art 3D camera for edge detection analysis. The experimentation results are validated by using a series of computational error and accuracy analyses and statistical methods including Mean Square Error, Peak Signal to Noise Ratio and Structural Similarity Index. The performance of an image processing algorithm depends on the quality of images and the algorithm utilised. The results show better performance of the fuzzy logic algorithm because it detects clear edges for installed panels. The applications of classical operators including Sobel, Canny, LoG, Prewitt and Roberts algorithms give similar results and show similarities in terms of the average of errors and accuracy. In addition, the results show that the minor difference of the average of the error and accuracy indices for Sobel, Canny, LoG, Prewitt and Roberts methods between both scenarios are not statistically significant, while the difference in the average of the error and accuracy indices for RGB-Sobel and Fuzzy methods between both scenarios are statistically significant. The accuracy of the algorithms can be improved by removing unwanted items such as vegetation and clouds in the sky. The evaluated algorithms assist practitioners to analyse their images collected day to day from construction sites, and to update building information modelling and the project digital drawings. Future work may need to focus on the combination of the evaluated algorithms using new data sets including colour edge detection for automatic defect identification using RGB and 360-degree images.

Unmanned Aerial Vehicle Impacts on Heat-Strengthened Glass

Increasing demand for small unmanned aerial vehicles (UAVs) in the logistics and rescue fields, which are closely related to urban environments, has been accompanied by an increase in impact risk to people and property. However, safety regulations for small UAVs in urban areas have not yet been well established, and there are very few studies investigating the collisions between UAVs and building structures that could occur in an urban area. In this study, experimental and numerical investigations are conducted to evaluate the damage resulting from a UAV collision with heat-strengthened glass, a widely used building exterior cladding. Commercially available UAVs were impacted into a series of glass panels at various speeds and angles. The collision processes were recorded with a high-speed camera, and the impact forces of the UAVs were measured using dynamic force sensors. A numerical model of the UAV was then developed to simulate the impacts using the finite element method and verified by comparison with the experimental results. The collision tests performed in this study are expected to provide primary data for establishing UAV safety regulations, and the verified numerical model can be applied to evaluate various collision scenarios for the different UAVs.

Especially The Use Of Windows And Curtain Wall In Climatic Conditions Of Russia

The use of translucent enclosing structures (TES - window and certain walls) in the climatic conditions of various regions of Russia requires special attention. Now the main operational parameters of this class of the protecting designs are considered strictly separately. Tests are also carried out for individual characteristics. In this case, neither the mutual influence of temperature characteristics on the possible change of operational parameters nor the assessment of the actual performance of the structure for a given region of construction are taken into account. A significant problem in the design of exterior cladding structures (including translucent) for cold climatic zones of Russia and other countries is to assess the feasibility and acceptability of their use. There is currently no explicit criterion for assessing applicability in regulatory documents. The authors carried out a large amount of experimental and theoretical work in order to develop criteria for assessing the range of applicability of this class of structures for different climatic regions of Russia. It is proposed to evaluate the possibility of using the TES for different climatic regions of Russia the use of a new complex parameter range of climatic applicability. this parameter includes the complex of the main operational characteristics of the TES - limit values of temperature and climatic influences on the TES (minimum outdoor temperature, the change of the reduced resistance to heat transfer, taking into account the different values of outdoor temperature, the maximum value of wind pressure, the value of air and water permeability, thermal deformation), in which the specified design standards

Sorption-Related Characteristics of Surface Charred Spruce Wood.

Surface charring of wood is a one-sided thermal modification process that can be used to create a hydrophobic, durable surface to exterior claddings. Spruce (Picea abies L.) wood samples were charred with a hot plate and several time-temperature combinations while using simultaneous surface compression. Temperature profile, water sorption, cupping after water exposure and density profile were measured. Furthermore, changes in the microstructure and surface functional groups were investigated by scanning electron microscopy and photoacoustic FT-IR spectroscopy. Results show that surface charring notably improves the hydrophobicity measured by contact angle, water floating and dynamic vapour sorption. Increased holding time during charring reduced the sorption but at the same time increased the dimensional instability measured by cupping. The density profile showed a shifting density peak with more severe modification regimes, indicating a more porous surface. The PAS-FTIR showed increased aromaticity of the surface that was also present in the pyrolysis zone beneath the surface in samples modified with longer holding time. Higher modification temperature affected the sorption as well as cupping positively but it is possible similar results can be obtained with lower temperature and longer holding time.

Field-based assessment of rock discontinuity and geological attributes of rock mass for stones for various engineering applications

Because of the occurrence of various rock types within the short span of areas, the Malekhu Khola area is one of the most promising areas where scope of stones is high. This paper presents recognition of the most promising rock types in terms of their geology and discontinuity for evaluating suitability for building stones. The research focuses on the assessment of nine different rock types allocated along the Malekhu Khola, central Nepal. Geological parameters, rock mass characterization and discontinuity analysis were carried out in each of allocated sites. During field study, rock masses were categorised based on different geological parameters, and on number of joint set, tentative block shape, size and volume. Field-based data were tabulated, analysed, and finally identified for the block size and geometry, and rock mass quality for stones. The number of major joint set ranges from one to four with random joint sets. The study shows that the outcrop condition of rock is faintly to slightly weathered and strongly indurated. The study shows that the rock types depending on the Rock Mass Rating (RMR) system vary from poor to very good. The block types that could be extracted are flat, long and compact. The probable end uses of these rock types could be armourstone, interior and exterior paving, cladding and foundation.

Natural Stabilized Earth Panels versus Conventional Façade Systems. Economic and Environmental Impact Assessment

More effective construction technologies are needed nowadays in order to reduce construction energy consumption during the life-cycle of buildings. Besides which, it is necessary to consider the economic feasibility and associated costs within the framework of these alternative technologies so as to favouring their practical implementation in the construction sector. In this sense, this paper presents an economic and environmental comparison of a new non-bearing façade construction solution based on the extruded unfired stabilized clay panels as opposed to three traditional solutions with similar physical, thermal, and aesthetic characteristics in terms of the exterior cladding. The proposed panels are a sandwich type configuration with an intermediate insulating material and two exterior pieces manufactured by extrusion with raw earth stabilized with alginate and animal wool fibers. In this paper, details of the constructive technology of the system are provided. From the results obtained, it is possible to conclude that the solution is a valid alternative from the environmental point of view, considerably reducing the Global Warming Potential and the Cumulative Energy Demand. And although the environmental improvement of the system can be considered the primary objective of this investigation, on the other hand, once executed, it will also be a competitive constructive technology from the perspective of the system’s final costs.

Experimental Researches on Determining the Fire Action Response of Improved Exterior Cladding Systems Provided with Incombustible Barriers

When a fire breaks throughout the exterior of a fire compartment, there is the possibility of vertical spread on the façade of the building, threatening the apartments of the upper floors. The main regulation in Romania (SC007-2013) states a number of technical and constructive requirements in order to limit the vertical spread of fire to the buildings which are thermal insulated with polystyrene. The aim of this research paper is to present the behavior of the proposed systems and solutions in case of fire and to optimize the width of a non-combustible barrier system to achieve the desired effect. There are also presented three laboratory tests for different design parameters and are being analyzed the results from fire exposure according to ISO 834 time-temperature curve.

Analysis of the influence of wood cladding on the thermal behavior of building façades; characterization through simulation by using different tools and comparative testing validation

New policies on energy efficiency in buildings aim to improve our environment. EU requirements on reduced energy demand to achieve Nearly Zero Energy Buildings are of equal importance to pollution and raw-material consumption. Addressing these parameters, building life-cycle analyses are needed, not only to reduce energy consumption, but also to encourage the use of renewable materials. Other priorities are building maintenance and construction material management at the end of the useful life of the building. The use of wooden façades is not very common in Spain. In this study, its energy efficiency is assessed against Spanish Government Regulations, through the Building Technical Code. Hence, this analysis of wooden façades examines their influence on the thermal behavior of the whole building, considering both material properties and structural design, focused on the exterior cladding or protective layer. These structures imply an optimized assembly design together with the application of a protective treatment, depending on its natural durability. “Radiata pine” was selected as one of the most common pine species in the Basque Country, suitable for cladding and grown in sustainable forestry programs. Several commercial simulation tools were used, such as: Therm, Wufi, and DesignBuilder aiming to a full thermal characterization of these particular enclosures, whereas the results obtained were finally validated through an experimental facility.

Blast pressure leakage into buildings and effects on humans

Abstract In the event of a bomb blast taking place outside a building at the ground level, a hemispherical pressure wave travels in all directions and impacts the buildings and other structures in its path. The exterior walls, windows, doors and the structural system are impacted. The pressure wave enters the building through broken glass at doors and windows, blast damaged exterior cladding and any other openings in the exterior of the building. The increase in ambient pressure experienced inside the building depends upon the area of openings in the exterior walls and the roof, the air pressure due to the blast at the exterior wall and roof surface, the duration of the blast and the volume of the interior space. Depending upon these factors, the interior pressure can increase above the threshold of human tolerance, thereby causing injuries to the occupants in the form of damage to lungs and eardrums, in addition to injuries caused by broken glass and other damaged building components. This paper will present a simple method of estimating pressure buildup near the exterior walls and other locations subject to leakage of blast pressure from the outside. The threshold of human tolerance to high air pressure will also be indicated.

Strategies for optimizing the environmental profile of dwellings in a Belgian context: A consequential versus an attributional approach

To date, many tools and guidelines to reduce environmental impacts from a life cycle perspective are available concerning the construction sector. However, basically all of them are modelled according to an attributional approach and there is a lack of studies that develop strategies for improvement based on a consequential LCA. The goal of this paper is to analyze to what extent the results differ when both models are applied on the same case, a representative dwelling located in Niel, Belgium. A conceptual optimization scenario for insulated exterior cladding has been added as well to examine to what extent different models affect the ranking of improvement strategies. For both approaches, the same foreground data and energy calculations are used, but the underlying structure of the models is different. The starting point is an attributional scenario, based on a Belgian guidance document ‘Environmental profile of building elements’ (EPBE) published by the Public Waste Agency of Flanders. The results of the entire life cycle indicate differences between the approaches, in direct relationship to the underlying modelling assumptions. The discrepancy becomes more pronounced when looking at the separate materials so the effect is not damped as a consequence of the aggregation in life cycle phases. Especially the three most contributing materials (steel, concrete and brick) show clear differences. The optimization scenarios underline previous statement, since the ranking of the different solutions is not equal according to both approaches. This research points out the emergence of a discrepancy between results when different modelling approaches are applied. The consequential model that complements the attributional EPBE study is therefore a useful addition to provide information for decision-makers. This way, the right information is available for all type of decisions.

Assessment of the European Standard for the determination of resistance of marble to thermal and moisture cycles: recommendations for improvements

The bowing phenomenon is so relevant that two projects, EU funded, from 1999 studied it and a European Standard to assess the resistance to thermal and moisture cycles (influencing bowing) has been recently adopted. In particular, according EN 16306: 2013, measurements of bowing and flexural strength should be performed before and at the end of the ageing cycles. Additional non-destructive tests are recommended, but are not compulsory for the standard. Moreover, Annex A of EN 16306 contains guidance on the limit values for the selection of marble types suitable for outdoor uses, especially facade applications. Eleven varieties of marble have been tested by means of this laboratory ageing test. Non-destructive tests such as the measurements of ultrasonic pulse velocity (UPV), adjacent grains analysis, open porosity, and water absorption have been executed together with the conventional flexural strength test. The results obtained from image analysis on thin sections indicate that the AGA index may not always be correlated with the other tests: amount of bowing, loss of flexural strength, or loss of UPV. Some consideration of the decrease in mechanical resistance and the bowing in relation to the variety of marble tested and the limit values indicated in Annex A of EN 16306 can be noted. It is known that bowing and rapid strength loss occur in some varieties of marble when used as exterior cladding and other exterior applications. Additional conclusions have been drawn: bowing and flexural strength correlate well and can be used to assess the suitability of the marble to be employed in outdoors.

The potential for cascading wood from demolished buildings: the condition of recovered wood through a case study in Finland

The aim of this study was to understand the current situation of wooden C&DW in Finland through a survey conducted on the demolition of a case study building. The results revealed that the extent of damage to the recovered wood is more dependent on the location than on the dimension. The condition of recovered wood from an integrated unit part (e.g. exterior wall panel) tended to be worse due to the attachment of other materials (e.g. insulation, plastic sheet), while recovered wood in better condition could be obtained from independent parts (e.g. roof truss, exterior cladding). These results would indicate that the cascading potential for recovered wood should be discussed in terms of both cross-section and location. In particular, the wood used as exterior cladding seems to have good potential for cascading and this could help extend the target for cascading wood from purely wooden building to other buildings.

Analysis of Time, Cost, and Environmental Impact Relationships at the Building-Material Level

AbstractRecently many studies have shown interest in understanding the relationship between different project objectives in the context of sustainable development in the architecture, engineering, and construction (AEC) industry. However, those studies were mainly focused on the relationship at the building level. The authors of this study argue that a better understanding of such a relationship at the material level is equally important, because many decisions related to design and construction methods are made based on the selection of materials or products. Therefore, the objective of this study is to determine data patterns of installation time, cost, and environmental impacts in terms of CO2 emissions at the material level. Six material categories, i.e., structural components, exterior claddings, insulation, roofing, concrete footings, and concrete slabs-on-grade, were analyzed to examine the relationship between material cost and CO2 emissions. Two scenarios were considered for each category to bett...

Adherence of Granite Plates by Mortar Adhesion: Influence of Temperature

The objective of this work was to study the effect of temperature variation on the adherence of granite plates fixed with adhesive mortars on external flooring and exterior cladding. The rock selected was a commercially well accepted syenogranite, known as Vermelho Capao Bonito, which has excellent technological qualities and high aesthetic value. Tensile bond strength and pullout tests were performed according to the techniques proposed for ceramic materials, in view of the lack of standards for dimension stones. The test specimens were set on standard substrates with two types of mortars, one commercially manufactured by a leader company and the other developed in laboratory. After normal curing conditions (28 days at 23°C and relative humidity of 65%), the adhesion tests were performed at the following temperatures: 23oC, 30°C, 40°C, 50°C and 60°C. With increasing temperature the results indicated a decrease in adhesion values of 48% to 42%, from 2.04 to 1.13 MPa for the one developed in the laboratory and from 1.92 to 1.12 MPa for the commercial mortar. The behavior of the microstructure on the standard substrate-mortar-rock interfaces were also investigated by optical microscopy, and no signs of reaction or penetration of mortars into the rock (anchoring) were observed. With regard to the adhesion values, temperature variation was an important factor to its decrease, offering important perspectives for new experiments with other types of granites, for studies of displacements and pathologies commonly observed in external cladding made with plates of these materials.

Moisture Performance of Energy-Efficient and Conventional Wood-Frame Wall Assemblies in a Mixed-Humid Climate

Long-term moisture performance is a critical consideration for design and construction of building envelopes in energy-efficient buildings, yet field measurements of moisture characteristics for highly insulated wood-frame walls in mixed-humid climates are lacking. Temperature, relative humidity, and moisture content of wood framing and oriented strand board (OSB) structural panel sheathing were measured over a period from mid-November 2011 through March 2013 in both north- and south-facing orientations in test structures near Washington, DC, USA. Wall configurations varied in exterior cladding, water-resistive barrier, level of cavity insulation, presence of exterior continuous insulation, and interior vapor retarder. The combination of high interior humidity and high vapor permeance of painted gypsum board led to significant moisture accumulation in OSB sheathing during winter in walls without a vapor retarder. In contrast, wintertime moisture accumulation was not significant with an interior kraft vapor retarder. Extruded polystyrene exterior insulation had a predictable effect on wall cavity temperature but a marginal impact on OSB moisture content in walls with vinyl siding and interior kraft vapor retarder. Hygrothermal simulations approximately captured the timing of seasonal changes in OSB moisture content, differences between north- and south-facing walls, and differences between walls with and without an interior kraft vapor retarder.