Plaster Ceilings Research Articles

Rapid screening of fibrous plaster ceilings health status using a laser Doppler vibrometer

The pressing necessity to determine a fast, efficient and rigorous approach to assess the health status of fibrous plaster ceilings across the UK motivated the research presented in this paper. Health monitoring techniques commonly used in the civil engineering sector are generally based on the measurement of the dynamic response of structures, such as buildings or bridges, using sensors (mainly accelerometers). This approach can certainly be adopted for suspended ceiling damage identification studies as well; however, the use of sensors directly connected to the ceiling might be prohibitive and time consuming and, therefore, more suitable for permanent monitoring systems. In this regard, in this study we explore the use of the laser Doppler vibrometer for the rapid screening of fibrous plaster ceilings health status. First, rigorous detailed studies have been conducted in the laboratory to assess damage using an ad hoc manufactured fibrous plaster panel using different sources of excitation in conjunction with the laser vibrometer. Damage indicators for the fibrous plaster ceiling have been introduced and validated through the laboratory experiments. Finally, the proposed approach based on laser vibrometer measurements and damage indicators has been applied to the Institution of Civil Engineers library ceiling in London, UK.

A three-stage approach based on 1D-CNNs for AE source localisation on historic fibrous plaster ceilings

A three-stage approach based on 1D-CNNs for AE source localisation on historic fibrous plaster ceilings

Load Bearing Capacity and Failure Analysis of Fibrous Plaster Wads

ABSTRACT Fibrous plaster is a culturally significant material used in high-status buildings from the late nineteenth century. Fibrous plaster ceilings are typically suspended using load-bearing fibrous plaster wads, which are attached to roof structure components. Understanding the behaviour of wads is highly significant, with important safety implications emphasised by the partial collapse of the Apollo Theatre ceiling in 2013. This study demonstrates an original, innovative test method for fibrous plaster wads that enables quantification of load capacities, with manufactured specimens representative of historic in situ wads. The methodology is rigorously evaluated for traditional and alternative wad designs, reinforced with hessian scrim or continuous fibre glass (CFG) mat, with and without steel wires in looped (untwisted) or looped-twisted configurations. Tensile tests generated load-displacement characteristics and determined failure modes including cracking of plaster, deformation and tearing of fibrous reinforcement, and if present, plastic failure of a wire. Results demonstrate that hessian performs better than CFG in axial tension and inclusion of a wire increases tensile load capacity and ductility. An industry standard repair wad with hessian and looped-twisted wire can typically support 3 kN. Looped wire performed better in isolation than looped-twisted wire, with higher peak loads and greater ductility, while looped-twisted wire carried a greater load as part of a fibrous plaster composite wad. The test methodology and findings have revealed new insights into the mechanical behaviour of wads which will inform commercial practice and conservation of historic buildings, preserving important heritage and promoting safe longevity.

Tensile failure mechanisms of historic fibrous plaster ceiling wads: Experiments at the UK Diamond Light Source

Fibrous plaster (FP) ceilings, prevalent in late 19th- and early 20th-century UK theatres, are suspended using ‘wads’. Wads are hangers made of Plaster of Paris, reinforced with twisted woven jute fabric. Several recent collapses in historic fibrous plaster ceilings have been attributed to tensile failures in wads. To understand the failure mechanisms involved, tensile tests were performed on laboratory-produced wad-like samples at the I12 beamline of the UK Diamond Light Source. The tested samples were designed with a dog bone shape and mounted with clevis-grips at each end, to ensure controlled failures along the gauge length. The beamline offered the opportunity to conduct simultaneous synchrotron X-ray computed tomography (sCT) and diffraction measurements during loading, enabling the monitoring of internal crack formation and strain propagation at the microstructural scale. Simultaneously, acoustic emission (AE) and digital image correlation (DIC) measurements were conducted. Preliminary results from these datasets are discussed in this paper. The datasets will provide useful information to validate the ongoing development of algorithms which can categorise the internal failure mechanisms and damage state of wads using only AE signals.

Interfacial bond strength and failure modes of traditional and modern repair materials for historic fibrous plaster

Many culturally important historic buildings contain fibrous plaster ceilings. The collapse at London’s Apollo Theatre in 2013, which injured 88 people, highlighted the importance of inspecting and restoring ceilings effectively. This study focuses on traditional and modern materials which are applied to the topsides of existing historic fibrous plaster ceiling elements during repair and maintenance. Fibrous plaster ceilings are commonly suspended from primary or secondary structural roof members using fibrous plaster wadding ties or ‘wads’. The application of additional repair material requires the formation of an interface, defining the strength of the repair. Properties of this interface were evaluated through a novel methodology employing pull-off tests’ of approximately 200 specimens consisting of Alpha plaster, Beta plaster, Jesmonite and Aramid gel. Notably, the effect of fibrous reinforcement, and compatibility with historic and degraded material was also investigated. This study has enabled quantification of interfacial properties and evaluated cohesive and adhesive failure modes. Importantly, the extent of redundancy within historic plaster ceiling practice has been demonstrated, with pull-off occurring from 0.5 kN to 2 kN loading, and the ductile behaviour of repair materials evaluated. Results highlight the importance of surface condition, with clean surfaces exhibiting double the tensile loading capacity compared to soiled (dirty) surfaces representative of those encountered on-site. The significance of this study lies in the quantification of repair material performances and consideration of variations in performance, methodology and in-situ environmental factors. Impact stems from the ability of practitioners to make informed decisions relating to adhesion performance when carrying out repairs. A key outcome is more effective preservation of historic elements in heritage buildings, higher levels of safety and serviceability.

EVALUATION OF MECHANICAL PROPERTIES AND ANALYSIS OF LOAD CAPACITY OF LATH AND PLASTER CEILINGS BASED ON TRANSITION OF SUBSTRATE SPECIFICATIONS AND CONSTRUCTION CONDITIONS

We have investigated several documents on lath substrate specifications of lath and plaster ceilings and evaluated their strength properties experimentally.

Riddle’s Court, Lawnmarket, Edinburgh

Riddle’s Court, a former merchant’s house situated off the Royal Mile, Lawnmarket, Edinburgh, underwent major refurbishment and transformation into the Patrick Geddes Centre for Learning from 2015 to 2017. The results from historical research, building survey and architectural watching briefs are as yet unparalleled, as no other building on the Royal Mile has received the level of historical and archaeological research carried out at Riddle’s Court.
 In the late 16th century much of the Royal Mile was a plethora of mainly stone and timber-framed houses. However, Riddle’s Court was an amalgam of predominantly ashlar and rubble construction with tall thatched roofs with dormer windows. Slate was a later addition in the early 18th century. The interior of the complex was furnished with several turnpike staircases of which only one now survives. During the 17th and 18th centuries Riddle’s Court was bedecked with all the fine trappings of a country mansion house and was occupied by major and minor aristocracy until the late 18th century. The status of the building was further elevated by its earlier royal connections that led to its partial remodelling for ceremonial purposes. A legacy of a lavish royal banquet in honour of King James VI of Scotland (James I of England) and his bride Queen Anne of Denmark was a painted ceiling in the so-called ‘King’s Chamber’ which commemorated their royal union. This ornate and historically significant painted beam and board ceiling was discovered in the 1960s during a period of building renovation by Edinburgh City Council. The ceiling was restored and is a focal point among a large collection of ornate plaster and painted ceilings. Subsequent removal of more modern lined ceilings during the present refurbishment led to the discovery of three more painted beam and board ceilings, and a concealed fireplace and bread oven that are rare survivors within not only the Royal Mile but elsewhere in Scotland. The presence of so much hitherto unrecorded artwork has significantly raised the importance of the Court’s North Block.

Investigation and conservation of historic suspended fibrous plaster ceilings

Significant nationwide consequences across the building sector arose from the Apollo Theatre ceiling collapse investigation relating to fibrous plaster suspended ceiling fabrication. This continues to be an acute issue as owners and developers attempt to resolve health and safety, risk and conservation of culturally significant fragile fabric. Fibrous plaster remains a problematic historic construction material because of its prevalence across the country, where it flourished particularly between the late 19th and early 20th centuries in theatres, hotels, music halls, churches and other public buildings, but also production and installation in current building works where typically very similar methods and materials continue to be used.

Four Worthies on plaster ceilings in Scotland (1617–25)

This article aims to contextualise a group of Scottish plaster ceilings dating from c 1617–1625 which all include roundels with busts of four of the Nine Worthies, to be found in houses identified by William Napier as comprising the Kellie Group. They will be viewed from two different perspectives. First, the Worthies will be considered as a subject popular in the literature and decorative arts of the period. Engravings of the Nine Worthies in a variety of formats enabled this medieval topos to retain its popularity throughout Europe in the 16th and 17th centuries. They featured widely in ornament and interior decoration of this period, not least in plasterwork. By setting these Scottish ceilings within this broader context, this paper will attempt to understand the reasons for their selection. Secondly, in the light of current research into London’s plasterwork and its production in the early 17th century, the provenance of these busts will be reassessed. In 1900 Lord Balcarres’s observation of the similarity between a plaster ceiling in his house and one from the ‘Old Palace’, Bromley-by-Bow, first appeared in print. The similarities included the repetition of roundels containing three of the Nine Worthies. The London building and/or its plasterwork had already been erroneously attributed to James VI/I for many decades and this article will present the historical evidence to dispel the myths which have continued to surface into the 21st century. In addition, the documentary and visual evidence that was adduced prior to the re-creation of two Jacobean ceilings in the State Apartment of Edinburgh Castle will be examined within these contexts.

Investigation and assessment of decorative plaster ceilings

Plaster ceilings are an intrinsic feature of historic buildings, from high-status palaces and public buildings with elaborate decorative ceilings to vernacular domestic interiors with plain flatwork. An appreciation of the stylistic development is the first visual evidence for assessing their cultural significance and intrinsic value. Periodic campaigns of decoration coupled with repair and restoration often serve to mask original materials, methods and condition, misleading the unwary and inexperienced observer. A comprehensive understanding of the materials and methods used for fabrication is essential in helping to form an appropriate conservation approach to minimise intervention and loss of original fabric in remedial works that may be necessitated by decay and deterioration, or even loss. The partial collapse of the Apollo Theatre auditorium ceiling in London in 2013 particularly highlighted and focused attention on the inspection and certification of historic plaster ceilings throughout the UK. This paper outlines some of the key materials, fabrication methods, agents of decay, investigation, and approaches to repair and conservation of historic plaster ceilings.

Historic plaster ceilings. Part 2: Survey, assessment and methods of conservation

Following last month's article on the historical development of plasterwork and the typical root causes of ceiling failure, part 2 now goes on to outline the practical assessment and interpretation phase: methods of underside and topside ceiling inspection, how to interpret the inspection's findings, and specifying an appropriate maintenance or remedial strategy.

Historic plaster ceilings. Part 1: Development and causes of failure

Recent collapses of sections of auditorium ceiling at London’s Apollo Theatre and Piccadilly Theatre, and the potentially significant consequences of ceiling failure, highlight a need for structural engineers to develop a close understanding of historic plasterwork and options for its maintenance and remediation. This two-part article provides an introduction to the subject, as well indicating where more detailed guidance can be sought. Part 1 outlines the historical development of the most common forms of traditional ceiling construction and summarises typical causes of deterioration and failure. Part 2 will discuss surveys, assessment and methods of conservation.

The Riding House: las caballerizas del siglo XVII de St. Giles House en Dorset, Inglaterra

<p>‘The Riding House’ es un ejemplo excepcional de la evolución histórica de las caballerizas de una casa de campo inglesa. El edificio, desocupado durante varios años, ha sido rehabilitado respetando su materialidad histórica y configuración de planta existente. Se partió de una inspección inicial y un análisis histórico para conocer el estado y evolución del edificio, así como para guiar los trabajos de conservación. La cubierta y suelos de madera han sido reparados introduciendo mejoras en las condiciones térmicas, acústicas y de seguridad contra incendios. Asimismo, se rejuntaron los muros y cosieron las grietas, reemplazando solo los materiales degradados sin posibilidad de reparación. Se han conservado igualmente los techos y tabiques históricos de listones y revocos de cal, suelos y carpinterías de madera, y se han reabierto aquellas puertas y ventanas tapiadas durante el siglo XIX para recuperar el diálogo visual perdido con la casa principal y sus jardines.</p>

Structural performance of fibrous plaster. Part 1: Physical and mechanical properties of hessian and glass fibre reinforced gypsum composites

Hessian fibre-reinforced gypsum, known as fibrous plaster, is a common material used for the manufacture of decorative features, including ceilings and walls in historic buildings, such as theatres and ballrooms, since the mid 19th century. It is still fabricated with modern materials for the decoration of new buildings in the UK, the Middle East and elsewhere. Following several recent failures of historic fibrous plaster ceilings in England, there is an urgent need to understand how these materials perform. There is no previous scientific investigation into the physical and mechanical properties of this material. As an initial experimental study, the microstructure of low and high density gypsum plaster were evaluated together with traditional hessian fabrics and modern glass fabrics, which are supplementing or replacing hessian fabrics. The chemical and physical characteristics were evaluated by X-ray diffraction, mercury intrusion porosimetry and dynamic vapour sorption. For the hessian, fibre density was measured and single filament strength measured to ascertain the effect of long-term ageing in new and historic material. Flexural tests were performed on gypsum plaster reinforced with different configurations of hessian and glass fabric reinforcements. Single filaments from historic hessian were weaker than filaments from new hessian and the larger scatter in strength was demonstrated using a Weibull distribution function. High density gypsum absorbed less moisture (0.2%) than low density gypsum (1%), as expected, but the jute fibres in the hessian absorbed more than 20% of the moisture. High density gypsum was considerably stronger than low density material, and random glass mats as reinforcement resulted in the highest flexural strengths and ability to yield to higher strains, due to enhanced interfacial bonding. This work will have high impact by providing a much needed basis for understanding the long-term degradation of fibrous plaster systems.

Evaluating Incidental Thermal Performance Improvements of a Historic Timber-Framed Building in Central Hereford

As we strive to decarbonise our historic built environment, a balance must be struck between technical, aesthetic, philosophical and economic concerns. Compromises must be made and opportunities seized. At the same time, evaluation allows us to assess decisions previously made and reflect on their outcomes. This paper presents the evaluation of the refurbishment of The Old Mayor’s Parlour, Church Street, Hereford, a historic timber-framed building now used as a gallery and exhibition space. The conservation work undertaken was not specifically envisioned as an energy retrofit, however the necessary replacement of failing concrete block infill, the legacy of a 1970s renovation, allowed improvements to be made to the thermal performance of the external envelope. Environmental monitoring and digital simulation have been used to assess the impact of these interventions. In situ U-value measurements show the success of the replacement infill panels and associated internal lining, although digital energy simulations suggest a limited improvement to the building’s overall energy efficiency. At the same time thermography suggests a potential threat of increased condensation risk to the uninsulated ornate 17th century plaster ceiling. The results of this paper show the risk of unintended consequences and the challenges faced by sustainable building conservation.

Harm

Harm Willie Fitzgerald (bio) My family last lived together in a two-bedroom apartment at the end of a long, dust-colored hallway. Our building was called the Emerald Arms, though only its front door was green. Our apartment door was purple, the trim a slightly different shade of purple, the worn hall carpet yet a third shade of purple. More of a lavender, really, my father might have said. Just outside our door, a love-struck end table offered three daffodils in a colorless glass vase. The flowers were made of a gritty plastic fabric; the water they stood in was resin. You could flip them upside down and they would stay just as they were. Inside, my parents had made the walls delirious with decoration. We had prints and postcards and prayer flags and pressed flowers and the framed (and signed) college magazine cover my father had done, an illustration of the Vietnam War in the style of Bosch's The Garden of Earthly Delights. In the kitchen hung Audubon's great blue heron, its neck turned down toward its feet to stay in the frame. Pewter incense bowls, a dull brass Ganesh, a money cat with half its face abraded. Wooden dinosaurs my brother, Paul, and I had painted when we were four and six years old, mine in fastidious segments of red, yellow, and green, his a muddy olive all over. A Walter Mondale campaign button resting at the teal pebble bottom of an otherwise empty fishbowl. Two thirds of our living room was taken up by a Colonial dining table too large to go anywhere else. This table, my father often reminded us, was a little older than America. How I mourn that table now! It was made of oak and stained somewhere between blood and chocolate; its underside still smelled, with sour authority, of cut wood. Paul and I had sawed, scored, and even gnawed on it like animals. Past the table was my father's art studio, which he'd demarcated with a yellow bed sheet hung from hooks screwed into the bumpy plaster ceiling. My father was a medical illustrator, and the wall above his drafting table [End Page 84] was covered with his work: splotchy melanomas, a furrowed brain, the chambers of the heart, all rendered on flimsy sheets of tracing paper. It was a home ill suited for boys, too full of fragile things. Some of them were valuable, too: in my parents' bedroom was a Diebenkorn study in pencil given by my mother's parents as a wedding gift; my father kept a handful of rare books locked in a barrister's bookcase in his studio. I had always longed to open one of those books, which, with their tattered leather spines and titles debossed in faded metallic serif, were indistinguishable from the grimoires that populated the fantasy books I read. One afternoon, I got my wish. The little golden combination lock had been left off the bookcase. My father often read late into the night, drink in hand, and must have forgotten. He was out for the day, and Paul and I weren't sure when he would return. I eased the glass door of the bookcase up and pulled out a book at random. That was how my brother and I ended up under the massive dining table with a copy—a first edition, it turned out—of Operative Gynecology, written by Dr. Herman Kelly and illustrated by Max Brödel. I was eleven. My brother was nine. We had opened the book hoping to find a fantastical bestiary or an index of incantations. Instead, we got our first tour of the female body. I remember one drawing of a man's pointer and middle finger fully inserted into (it took me a moment to realize what I was looking at) a woman's rectum. The doctor's thumb rested in the woman's pubic hair. The woman's abdomen had been cross-sectioned along its vertical axis to reveal the doctor's fingers, the walls of her colon, even the bubbly interior texture of her vertebrae. I turned the pages, saw swollen and diseased labia, prolapsed...

Shaking table tests on seismic response of backdrop metal ceilings

In recent earthquakes, the failure of ceiling systems has been one of the most widely reported damage and the major cause of functionality interruption in some buildings. In an effort to mitigate this damage, some scholars have studied a series of ceiling systems including plaster ceilings and mineral wool ceilings. But few studies have involved the backdrop metal ceiling used in some important constructions with higher rigidity and frequency such as the main control area of nuclear power plants. Therefore, in order to evaluate its seismic performance, a full-scale backdrop metal ceiling system, including steel runners and metal panels, was designed, fabricated and installed in a steel frame in this study. And the backdrop metal ceiling system with two perimeter attachments variants was tested: (i) the ends of the runners were connected with the angle steel to form an effective lateral constraint around the backdrop metal ceiling, (ii) the perimeter attachments of the main runner were retained, but the perimeter attachments of the cross runner were removed. In the experiments, different damage of the backdrop metal ceiling system was observed in detail under various earthquakes. Results showed that the backdrop metal ceiling had good integrity and excellent seismic performance. And the perimeter attachments of the cross runner had an adverse effect on the seismic performance of the backdrop metal ceiling under earthquakes. Meanwhile, a series of seismic construction measures and several suggestions that need to be paid attention were proposed in the text so that the backdrop metal ceiling can be better applied in the main control area of nuclear power plants and other important engineering projects.

Ventilation of Low Slope Roof Systems in Northern Climates

For over generations, multi residential (flats) buildings were constructed in North American with low slope roofs. The roof design included an interstial space of 1.5 to 2 meters between the ceiling and roof deck. This ‘attic’ space was typically vented via static air vents. The ceilings were typically constructed of plaster with little or no insulation. The roofing was typically asphalt or coal tar built up roofing applied directly to the roof deck. This simple ceiling to roof arrangement worked for centuries. In circa 1998, with the advent of mandated reflective roofs in several large North American cities, a simply workable design was changed, often with disastrous results. So that greater floor to ceiling heights could be attained, the 1.5 to 2 meter attic was reduced to .33 m or smaller. Plaster ceilings were changed to gypsum board. Fiberglass insulation with an ineffectual vapor barrier was installed at the ceiling, and often punctured by ‘can’ lights which allowed air transport of warm air, often containing moisture, into the attic cavity. With no attic ventilation, insulation on the roof deck, condensation accumulation on the attic structural elements to such a degree that, in many situations, resulted in the deterioration of the wood structural elements.This paper will review the importance of proper design with ‘modern day’ low slope roof systems with ceilings on the roof structure, and the role that venting, vapor retarders and roof color have on the success or failure of these roof systems. The author will review historical examples of recent failures and provide designers with recommendations for appropriate low slope residential roof system design.

PyroShield - A HVAC fire curtain testing robot

Abstract Fire curtains (or dampers), as found in HVAC ducts, are drop-down thermally triggered fire-resistant barriers designed to block the spread of fire and smoke. Regulations stipulate regular mechanical drop-down testing as a visual inspection may not identify rust or jamming which may prevent a curtain from falling. Currently it is difficult to test these curtains as many HVAC ducts are small (340 mm × 330 mm) and access hatches often don’t allow direct external access to the thermal fuse. Hence complete testing may require the temporary (and expensive) removal of plaster walls, floors or ceilings. This paper describes a pair of tele-operated robots which are designed to mechanically test the operation and serviceability of the fire curtain. Significant experimentation has demonstrated that the testing procedure requires a skilled operator and can be performed typically within a 15 minute timeframe without the expense of renovation and remediation procedures.

材料物性と下地仕様の観点からみた木摺り漆喰天井部材における基本性能と健全度評価に関する実験的検討

In the Great East Japan Earthquake, a large number of buildings collapsed and the strength of ceiling boards using plaster finishing was occurred as serious problems as a possible problem. That is why, since the Great East Japan Earthquake, the owners of old buildings are concerned about the deterioration of the building components. Therefore the number of owners seeking to strengthen their building's components have been increasing day by day. Moreover, in addition to preserving these historical buildings, it is also necessary to secure the safety from the standpoint of cultural and historical values. Therefore, we focused on these wooden lath and plaster ceiling that's used as a target of evaluation for saving the historical building. In this study, an experimental study of inspection of an existing wooden lath and plaster ceilings, we evaluate the strength and other properties of plaster, and finally conduct the objectives to prolong the duration of life with safety conditions. Plaster materials have been frequently used in old building's ceilings and walls. In general, the role of plaster ceilings are to transfer stress buffering between the lath and plaster. Therefore, it is important for the lath and plaster to be strongly adhered. This portion has been called Plaster Key in general and its role is to evaluate the mechanical properties of the plaster ceiling and wall. In Japan, this type of ceiling using plaster and mortar has been used from the early 1900s, and over a century has passed since the lath and plaster ceilings were developed, and at the same time the plaster has been frequently damaged in earthquakes. Stress transmission of lath and plaster are into the four patterns. The shear resistance is a stress. Shear is a stress that caught the lath. The tensile resistance is a stress that support the load of plaster. The bending resistance is a stress against the deformation of the plaster. The adhesive resistance is the stress of the adhesive surface of the plaster and lath. The lath and plaster ceiling specimens could be evaluated to measure the strength conditions of the ceiling member. This specimen was made in suspending conditions of same environment of the ceiling. The tensile testing instrument was attached to the surface of the finishing plaster after curing. The tensile strength test was enforced to pull plaster against the lath and record the peeling resistance in maximum load, the plaster deformation, and destruction pattern of plaster key. The results of strength examination of the plaster containing fiber, the maximum stress of the plaster was increased, and the fracture energy was increased. The case of including small fibers was effective at increasing the shear stress, stress in a similar function as reinforced concrete rebar. Then, as for the plaster containing sand, the maximum stress was not increased. As for the flexural strength, the plaster including the maximum amount of fiber was increased by increasing fiber contents, and the fracture energy of the sand was reduced. The results of strength examination by the lathing plaster specimen, the breaking load was correlated with the width of the wooden lath clearance. As the length between wooden lath and the plaster is closer, the length between the lath and plaster, the plaster key would expect strong mechanical interlocking conditions. However, if the amount of sand is too large, the positive effectiveness was eliminated, the strength would be decreased.