LIGHTWEIGHT WALL SYSTEM CONSTRUCTION ELECTIVE Ross Pirie // 0805621
This project is to create a space for The space should be around 20m2 in be an entirely independent building likely built in the garden of an existing
a writer. area and - most dwelling.
The main ambition is to explore a system that essentially cuts out ‘the middle man’ ie. the joiner/ builder so that the process from design to completion can be quicker and simpler yet still retaining the architectural qualities of the project. Can alternative materials be explored to the conventional pallets that we are a custom to? How will the system be put together - a kit of parts or a construction guide? Can this be done in the fewest parts possible and in the simplest way? Can the system utilise the growing phenomena of 3D printing? This is what the project aims to explore.
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INTRODUCTION
WORK OF DAVID MIKHAIL, VARIOUS, LONDON The aim for the project is to create a lightweight external skin that has an aesthetic that is similar to the images opposite. Transparency will be key to allow light in for this writers studio - however an alternative to glass will be explored in order to create something more interesting and cost efficient.
HYBRID HOUSE, SANDER ARCHITECTS, FLORIDA This project utilises prefabricated panels in order to create a seemingly transparent facade that is punctuated with glazing panels. The aesthetic of this is interesting in respect to the juxtaposition of translucent panels and glazing and the light emitting through. The panel concept seems most logical for what my project is aiming to achieve.
LIYUAN LIBRARY, LI XIAODONG, HUIAROU The internal space creates a quality of light that would be suitable for working in but also aesthetically pleasing. Simplicity in the structure and construction is interesting. PAPER HOUSE, SHIGERU BAN, YAMANASHI The composition of light facade and heavy internal load baring structure creating two varying internal spaces is an idea.
PRECEDENT
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CONCEPT SKETCHES
The parti diagrams opposite demonstrate the ideas that have been taken from the precedents : a double skin and the separation of spaces. What the internal space is has the potential to vary, but will predominantly be a load-bearing structure to support the roof. This structure can be of simple stud wall construction and doesn’t have to deal with the challenges that an external skin has to deal with. Therefore the main interest is the external wall system and how this will be formed. Doing this without the use of glass will be the main challenge. This aim is to create a light-weight system but the issue will be creating transparency and allowing light to penetrate to create an environment that is suitable to the buildings function. The initial architectural intent is to use these two skins to divide up the spaces. So that there is an interior space within the heavy skin that will be used for writing and the space out with that will be used for reflecting, pondering, thinking or meeting. The building should be simple and easy to construct to avoid any confusion in the erection process. The system that is created should not be complex itself in order to allow a cheaper build cost. Keeping this in mind the system should be reduced to as few parts as possible.
CONCEPT SKETCHES
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The coming together of the parts should require as little man-power as possible and ideally would only take one person to construct. However this may not work entirely with the roof. Therefore the connections between each of the elements will be key to the success of the system. Is there a possibility that instead of this being a system that is ‘off the shelf’ can this be a design guide that can be constructed at home as a ‘do it yourself’? The sketch demonstrates how the system might begin to come together and how many panels/parts will comprise of the system. The main structural issue at present will be how the roof is connected and integrated into the wall system so that there is a consistency. Also how doors are fitted within this wall system will be key.
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CONCEPT SKETCHES
THE CELLOPHANE HOUSE, KIERAN TIMBERLAKE ARCHITECTS, NEW YORK This project was part of an exhibition in new technologies arising from developments in off-site manufacturing. The architects were looking to develop their material creation - SMARTWRAP - and explore it’s use in a domestic project. The material is a sophisticated plastic that is used instead of glass to create a transparent skin around the building. The double skin has an external layer that has small PV panels integrated so that the cladding is also producing energy for the dwelling. The construction system is efficient as the building is split into components and panels that fit together with relative ease on site, creating a desirable internal environment and external aesthetic. In principle this is an extremely interesting idea however the cost and sophistication of such technologies is out with the parameters of this project. However the idea of plastics being used as an external cladding is useful. This part can be pursued in more detail.
MATERIAL PRECEDENT
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INITIAL MODEL
ETFE is a relatively new material within the building industry. It is extremely light-weight and performs well acoustically, environmentally structurally and can achieve U-Values as low as 0.3W/m2K. The principle use for this is material is in ‘pillows’ or ‘cushions’ that are used in wall or roof systems. These pillows allow necessary amounts of lighting as well as performing well insulitivly to create an envelope that requires minimal structure as it is a fraction of the weight of glass. Plastics, paper and foil are materials which are becoming more frequently used in building skins, especially the work that Shigeru Ban has done throughout his career with paper and it’s possibilities. So there is an opportunity to explore these materials further. The possibilities with plastics seem almost endless. The use of ETFE again is something that is more sophisticated therefore it makes sense to look at something more low-tech, such as cling film. As a material when it is wrapped in several layers is incredibly strong and is used to turn single glazed windows into double glazed units. From this the project will now explore the use of standard cling film as a building skin.
ETFE & PLASTICS
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CONCEPT SKETCHES
The first model looked at a frame that was then wrapped in cling film. This was an initial study into the possibilities of the material as a skin and how it would perform in an external environment. This model was in part a failure as there was no real elegance and sophistication to the system. There would also be issues with forming door openings if the skin was wrapped completely around it and the span of the skin would also be an issue with deflection. The build-ability of this was not what was required of the brief either. This confirmed that panels would be the more efficient solution and it is this route that should be explored further.
INITIAL MODEL
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The panel system provides a solution that can make the writers studio as flexible as possible. This gives an opportunity to test the widths and heights of the panels , how many times they should be wrapped. Also how they are connected side by side as well as at the corners. This will also allow door openings to be made more easily.
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PANELS CONCEPT
Once the panels had been constructed and then wrapped in various layers of plastic - three, six and twelve - it was vital to test the daylighting qualities that each produced. The results were not overly surprising. The ‘three layers’ performed the best in allowing more light through and also had the greatest visibility through the panel with minimal reflectance. The twelve layers allowed the least light through but a glow of light was achieved - not complete darkness. Visibility through the panel was poor and there was a high reflectivity off it. The six layers was in the middle of this. However the results and their success or not would have to be compared against the strength of each panel in order to assess which is most suitable.
DAYLIGHT ANALYSIS
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3LAYERS // 6LAYERS // 12 LAYERS
In a single layer cling film is easily pierced, however when wrapped several times becomes much stronger and tensile. However there is a need to test this to see how many layers will be needed to provide adequate protection for the skin for the system. This will follow on from the testing of the daylight as there will need to be a balance between visibility and strength. The tests will be carried out using incremental weights and a set distance to drop objects from to enable comparative results. The results were as expected - the more cling film used the greater resistance to point loads they had. From the chart on the following page it is reasonable to conclude that the resistance increased dramatically between 3 and 6 layers but between the 6 and 12 layers the increase in resistance was dramatically less. During the initial testing of the three panels with varying layers it was evident that further methods of the application of plastic would need to be explored in order to maintain the strength but reduce the volume of plastic that was being used.
PLASTIC STRENGTH
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Heating cling film or other specially designed plastics has been proven to improve the thermal performance of a window. Essentially this turns a single glazed window into a double glazed window. During the process of heating the plastic expands and is stretched, when it cools it then contracts which results in the plastic becoming stronger. Therefore these principles can be applied to the wrapping of the panels. As each layer is being wrapped around each side a hair dryer is used to heat the plastic , stretching it, meaning that when it contracts, theoretically it becomes stronger. The more layers that it is wrapped around the stronger it should become. This will allow less plastic to be used in the cladding process but still maintaining the same strengths. The testing on these panels proved that heating the plastic as it is being applied greatly improved the strength of the skin. The 6 layered panel was now able to withstand the same force as 12 layers that were not heated. However the main problem is that the 5kg load still penetrates both internal and external skins. A solution to this will need to be explored.
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HEAT TREATING
STRENGTH TEST RESULTS
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Applied weights were also explored as opposed to point loads, to demonstrate the strength of the skin. Two subjects were used, one weighing around 75kg and the other 95kg. Both were tested on the 12 layers and the 6 layers that was heat treated. Both panels were able to take these loads with very little deflection or damage to the skin. The underside was completely unfased by this testing. The sketches opposite demonstrate the thinking between the strength and the transparency of the panels and the volume of plastic used - all as a result of the testing so far.
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APPLIED LOADS
STRENGTH vs TRANSPARENCY vs VOLUME OF PLASTIC
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MONOFILAMENT AND FILM
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PROCESS
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The monofilament wire has been added to give the panel additional strength. This product has been selected as it is a continuation of the idea of wrapping, but also as it is made from nylon has high tensile strength and is also clear so almost disappears when wrapped in cling film. The wire is 0.22mm thick and has been wrapped round the panel in a weave pattern - almost like a tennis racquet. This should improve the strength and help spread the load of any impacts. The wire and film panel was now tested under the same conditions as the previous panels - starting where the last on failed. Unfortunately the panel still failed. The film was torn and even the wire was beginning to fail although was still intact. The positive was that only one side suffered damage compared to complete penetration on both sides - like previous panels - this was a result of the wire being arranged in a lattice, it absorbed much of the impact and the object bounced off. The damage done by the impact is evident in the images below.
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MONOFILAMENT AND FILM STRENGH TESTS
Further exploration is therefore required into how the skin can be improved to resist these point loads. However there are limitations to this process. The main idea surrounding the progression is the lamination of materials, for example glass and timber are made much stronger when they are bound in layers with a glue or resin. Laminated glass in particular has multiple applications within architecture as well as the automotive industries. This process involves heating and pressure to bind two pieces of glass together. The binding agent is polyvinyl butyral (PVB) which has optical clarity, can be adhered to many surfaces, is tough and flexible. This material is therefore ideal to include within the layering of the panels skin as a result of the properties mentioned above - specifically the clarity and strength. This would be applied to the skin in between the layers of cling film with the wire lattice woven in between to increase the overall resistance. This laminating process will greatly improve the overall strength of the panels but would maintain the lightweight and transparent nature that was the initial concept. The layers of PVB can also be coloured as shown in the image above. This could allow an aesthetic improvement to the panels which cling film alone could not provide.
HOW TO IMPROVE THE STRENGTH?
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FIXING THE PANELS
The panel system will need to be connected in such a way that allows it to be erected and deconstructed easily and without any damage to the components. Nails or screws will obviously not suit these aims and nor will any wet connections. Therefore a clamp system will be most effective. The aim for this system will be to use as little components to make this work, but the main challenge will be how the system provides a continuous insulative envelope. The initial thoughts tried to determine if a single clamp system could be used for corners and linear connections - however through sketches this will not be feasible. The initial ideas looked at a series of clamps (next page) that would be fixed at equal centres and then finished with a capping piece at either side. However to reduce the number of parts the design changed to have a single piece of metal with threaded bars welded to once side that would then be bolted together on the inside. Aesthetically there would still need to be a capping piece in order to finish the system. In terms of insulation there would need to be a neoprene insulative strip that ran the length of the metal bar to create a thermal break between the panel and the clamp.
CLAMP SYSTEM
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CLAMPS
INTEGRATING ROOF AND CLAMP SYSTEMS
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INTEGRATING HANGER SYSTEM
With the initial clamp system fairly resolved there was an opportunity to develop it further to allow this system to become part of the supporting roof structure. The ideas was that the primary beams could be supported in the gaps between the panels. This could be done by having a hanger or some sort of fixing system. The main loads would be taken by the internal structure as per the initial concept. This hanger piece would be welded to the external metal bar to create a single piece. The timer beams would be secured by bolts. Again utilising dry and easily de-constructed connections. How this system goes together is detailed in the diagram opposite.
ASSEMBLED COMPONENTS
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THREE CONNECTIONS
For the whole wall system to go together there will be three types of clamps that will be used: 01.- HORIZONTAL CONNECTION : where two panels fit side by side with no beam to carry above. 02. - CORNER CONNECTION : where two panels meet at 90 degrees, this connection has the same principles as the others just that the metal bar is shaped differently. 03.HORIZONTAL CONNECTION WITH HANGER: exactly the same as 01. but a hanger piece to support the primary beam above. This means that the connection themselves become load bearing so there will need to be exploration into the foundations and how these clamps are fixed and sufficiently structural. This may be as simple as using 8mm steel as opposed to 4mm as per the other connections. Or the foundations may include a ‘shoe’ system that the clamps slot into. The roof itself may be similar in ideas to the wall system - the theme of wrapping and panels may continue however this has not been explored fully.
CLAMP DETAIL
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MAKING THE CLAMPS
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MAKING THE CLAMPS
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MAKING THE CLAMPS
The process of making the clamping system was laborious to say the least - however if the elements were produced under factory conditions then this would be a more efficient way. Learning the processes involved to create this influenced how I would alter the design in order to make it more efficient and easier to produce. Most notably the profile of the corner clamp would change - but this was down to the availability of product at the hardware store. This was actually the main issue - as what I had designed in terms of sizes and profiles - was not readily available.
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MAKING THE CLAMPS
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MAKING THE MODEL SCALE 1:2
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MAKING THE MODEL SCALE 1:2
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MAKING THE MODEL SCALE 1:2
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MAKING THE MODEL SCALE 1:2
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MAKING THE MODEL SCALE 1:2
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MAKING THE MODEL SCALE 1:2
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WATER-TIGHTNESS
Testing the system for its water-tightness is an important part of the overall system. The level of testing was basic however there was significant issues and conclusions drawn from this. Firstly the panel was successful under a small volume of precipitation, as demonstrated in the first test paper. However when a larger volume of water was poured on top it was evident that there were some gaps allowing water to penetrate. This may have been a result of the way in which the panels had been laid to rest which may have allowed them to drift apart. Regardless this is an issue that will need to be addressed - specifically in the clamping system. This may be resolved by adding a sealing strip or even the proposed neoprene insulation may be enough to completely seal this gap - along with the proposed teeth that grip the panels together. On a positive note there was no water penetration of the plastic and the way in which they had been wrapped did not allow any water to get in between the layers of plastic. The water also ran straight off the panel.
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TESTING
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FINAL IMAGES
This project has explored how a lightweight wall system can be developed without using glass as the transparent material. Ultimately this is a system that can be built relatively cheaply and can be put together by one or two people person without employing any tradesmen. The system has been designed in such a way that it could be constructed so that all that is required is a design manual - or can be bought as individual components (panels, clamp system). The use of plastic instead of glass allows the system to be 100 times lighter than what it would be in glass. Also the panels can be varied between transparent and translucent depending on whether the user wishes to see out or have privacy but still allow light into the building. Also any of the panels become damaged then they can easily be removed and re-wrapped very cheaply and quickly - unlike fixing a broken window. The design of the clamping system means that the whole system is easily erected as well as deconstructed - without any damage. The integration of the hanger for the beams means that the overall number of parts to the system is greatly reduced - meaning that the system is easier to put together. Although this system may not be effective in permanent domestic situations there may be an opportunity to explore its application in disaster relief housing. There are still issues in terms of thermal bridging. Although the panels would perform well individually,
CONCLUSION AND CRITIQUE
where they join and the clamps themselves present a point of weakness. This could be resolved by using neoprene insulitive strips on the inside of the system to create a complete thermal break. Air tightness and condensation - particularly the internal skin - will also be an issue. This may be resolved by creating a tricklevent system within the clamps to allow the internal environment to be controlled and reduce the risk of internal condensation and breath-ability issues. The corner clamping system may need to be reworked there may not be sufficient grip and stability created even if there were teeth to clamp into the timber panels. They could be designed to wrap around the panels and grip at both sides of the corner. However this may cause greater risk of the panels plastic layer tearing. In fact if a ‘tooth’ system was applied to the panels and there was a great deal of movement within the wall and even the roof, there would be a possibility that the plastic could tear. An alternative to this should be explored if the project were to be taken further. There would also need to be further development into clamps as the one that includes the hanger becomes structural. This would mean that there would need to be some development of the foundations and how they would fix to these clamps. This could take the form of a shoe or some other fixing. The roof system would also require to be developed further in order to make a complete building.
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