Friday, 27 September 2013

A brief romance with a production line

In the first half of the twentieth century, architects idolised the production line as a means of clinically and economically producing buildings.  Arguably the most standardised building type is the house and the production line promised to bring us closer to the ideals of machines for living in, or homes as service equipment, not monuments.  But the production line never radically changed the building industry.  By comparison to the pace of development in other industrial sectors, it is surprising that the building industry has taken so long to evolve.

The traditional approach to building, which the simplified diagram below attempts to explain, shows a distinct separation of roles between the (coordinated) design team and the building contractor's team.  The design team need to ensure that the contract information provided to the contractor is accurate, buildable and coordinated.  Once on site, the main contractor is responsible for the delivery of the built project and often has the lion's share of control over the works, within the parameters of the contract.

Simple diagram which aims to illustrate the relation ship between designers and contractors on a traditional build.
For comparison with those below.

With all the technologies available to us on the twenty-first century, it is surprising that building is still such a messy process, relying on wet trades and estimated quantities of base materials brought to site which, by comparison to other manufacturing methods, can consume a lot of materials and produce a lot of waste.

Even with the huge demand for housing, most of it is produced using site based labour and traditional trades. 

The UK saw it's chance to adopt production line technologies for the first time, after the Second World War, in the post-war rebuilding programme.  Using the aircraft industry to support the building industry, surplus war planes were recycled for their aluminium and converted in to bungalows on a mass-produced scale.  Working under factory conditions brought designers and fabricators to a closer working relationship.  The factory environment also allowed greater control, use and re-use of materials, thereby limiting waste.  The product was typically four building sections which could be fitted together by a site team, on a prepared site, in one day to make a house.

The production line promised to bring design and fabrication roles closer together.   The factory environment allowed greater control and accuracy over the product.  Material quantities could be more easily controlled, with the ability to reuse surplus materials and recycle waste. 

The most successful product (by quantity) was bungalow B2 by the Aircraft Industries Research Organisation for Housing (AIROH).  Over 54,000 units were produced by four aircraft manufacturers in the UK, including the Bristol Aeroplane Company in Weston-super-Mare. 

The first production line in the UK to produce buildings!

Logistical restraints play a vital part of prefabricated construction.  The bungalows were transported to site, by road in four sections as shown below for an exhibition at the Tate in 1945.

Four sections of the bungalow B2 arrive at the Tate in Pimlico, London.

Specific on-site plant for lifting and manoeuvring the prefabricated units was also essential, as was a site team experienced in handling and assembling the prefabricated units.

The pre-fabricated sections are positioned on a prepared base.

The sections were pushed in to place, and junctions welded up to make a watertight enclosure.  The services were also connected to the main infrastructure through the base.

Making the connections and completing the assembly.

With aluminium in abundance, and many workers experiences in fabricating this material in the 1940's even the kitchen, including the doors, was made with aluminium.

This approach offered some significant advantages over standard construction methods.  Site assembly time was quicker, with less site waste.  Transportation to site was greatly reduced, with only a few parts to deliver, saving transportation fuel.  This also meant that by necessity the buildings were lighter, using less material resources.

There were disadvantages.  This approach lends itself to a standardised single product solution.  Variation in the product is difficult to achieve and not cost effective.  That's why cars are identified as particular models and makes, with variations generally restricted to colour, optional extras or whatever you might add in the way of stickers or furry dice etc.  Another disadvantage is that factory based production systems often rely on a set range of components, prescribed by what is on offer within the factory.  The material palate and selection of details can be limited.  Also, one key disadvantage to this trial was that although the houses were produced quickly, they cost significantly more than their traditionally built alternative.

With these bungalows, there is also the thought that the aircraft industry did not capture the imagination of the public (or design professionals) with these aluminium homes in the same way as we idolised aircraft manufacture, the marvels of flight and how it was achieved with structures like the monocoque fuselage.  The bungalows, although very adventurous in many ways, didn't seem to have the same progressive aesthetic.  Perhaps too many building details were lifted from existing war time structures familiar to the manufacturers, which consisted of temporary buildings and military camps.  With the details followed some of the aesthetics.  It would be an interesting investigation to look in to how much the Architectural profession and building industry was involved in these production line experiments because following the Second World War, the RIBA was active in trying to return the building industry to more traditional materials and production methods.  I suspect they were driven mainly by the aircraft industry.

These bungalows were also a product of central government control.  At the time, the Ministry of Works wanted to see what could be achieved with factory production, new materials including metals and how they could be combined as composites.  There was a surplus of people who had been working for the war effort, with factory skills needing employment after the war.  There was also an active steer away from traditional site labour and traditional building materials such as brick and timber, which were in short supply.  This is why most of the photos of post war bungalows show them sitting behind wire fences with concrete posts above concrete paving slabs.  The environments look a bit austere by today's more demanding standards, but they offered a marked improvement in their day.

Today production line buildings largely restricted to producing Portakabins which we identify as a standard temporary building type with limited aesthetics, or modular buildings often for service and utility use.

The traditional site-based approach to building does have a key advantage over the production line, that each building product can be made different and individual, and it is this versatility and flexibility which the building industry works well with and relies on for the variation we have in the built environment.  There are several advantages of the production line approach and prefabrication which we can draw on to make the site based approach more efficient, quicker and potentially more economical.

Using prefabricated specialist products with closer integration and coordination during design offers millimetre accurate components which can potentially be transported to site from different locations, with confidence that they will fit and perform as required.  It also potentially means a closer, more integrated working relationship between design professionals.

More and more, prefabricated components have played an increasing role in the building industry.  Even on the standard housing build shown above, items like window units and roof trusses will be prefabricated.  The more which can be prefabricated, the less chance there is of un-necessary site waste, and the quicker the site programme.  There is the potential to involve less wet trades on site, and for buildings to weigh less, using less material resources.

This process relies on the close involvement of specialist fabricators to work at its best.  BIM and 3D CAD has given us the opportunity to share design information with specialist fabricators with the confidence that items produces will (or should) fit on site.  It gives a huge range of choice for material and detail selection because specialists can be chosen to suit the project, supporting the building industry's requirement to produce individual buildings or sets of buildings with variations.

The Richard Rogers Homeshell project is a great example of this approach. It uses a set range of components which can have variations as required for each house type.

The system is very simple, which should help to make it economical as a competitor in the housing market.  The key ingredient is the Insulshell panel.  This provides the airtight external insulated envelope, primary structure and lateral stability to the house, with timber framed prefabricated panels.  The design of the system allows complexed geometries to be managed.

The fabrication is kept simple, as is the and jointing and weather sealing.  The external walls are clad with a rainscreen and the inside lined out with a plasterboard finish.

Looking up to the underside of the roof and it becomes apparent that there is no separate structure.  The timber panels do all the work.  They are the primary structure, lateral stability, thermal resistance, air tightness and set out the geometry of the building.

The inside reveals that there is no additional structure.  The Insulpanels are doing all the work with a combination of timber assemblies.  This greatly assists the speed of the build and should help to reduce costs, but it also means that during design the Architect, Structural Engineer and Specialist Fabricator need to work closely together on this one product.  This is something that has been noted before in a previous post.  It means a departure from the traditional way of working where each consultant works on their separate area of expertise and the Architect coordinates to check that everything will fit, with the proposals then going out to the market for pricing.  Here structure, aesthetics, and environmental requirements (insulation and air tightness etc.) are all rolled in to one product.  Speaking to Don Blacklock who heads up the Insulpanel division of SIG, he stressed the importance of involving specialist fabricators in to the design discussions as early as possible, to make the best use of the potential efficiencies and economies available (which in my experience is before the Structural Engineer can say 'cross bracing').

Internal walls are structural timber cassettes, performing several design roles.

Key to all prefabrication projects, as noted above with the aluminium bungalows, are:
  • Logistical restrictions and the size of components which can be carried to site, 
  • The correct lifting plant and 
  • Use of trained installation teams on site.  
This time-lapse film of the Homeshell installation at the Royal Academy, Piccadilly, London, illustrates these assembly principles.  (There are some distinct similarities to the installation of the B2 aluminium bungalow at the Tate, 68 years earlier).

Perhaps the biggest hurdles to this type of development taking off are:
  • Economics.  The system (product and process) must have proven cost advantages over traditionally built houses.  Products like Insulpanel must be cost effective compared to a cavity brick wall, which is one reason it looks so simple.  
  • A shift in the structure of design teams: More integration over component design with the involvement of specialist suppliers as part of this process.
  • A shift in the way the building industry works: Managing specialist fabricators in relation to supply to site in relation to programme.  Addressing logistical restrictions and specialist lifting plant requirements to replace lorry loads of materials and scaffolding.  
  • Contractual responsibilities: Including clarification of design responsibilities which result from more integrated working relationships.  Also there are issues over who would be responsible for sub-contractor appointments, if they are tied in to the design leaving the main contractor no choice but to adopt them.
  • Aesthetics: An alternative solution to traditional building needs to be accepted by the public as a clear preference to traditionally built homes, or the victorian terrace etc.  The solution needs to be marketed so that it is not seen as an experiment, temporary or something different or quirky.  

Some lines of development to be played out?


Tuesday, 10 September 2013

Working with Schools

With increased demand for school places there is growing pressure to extend existing school buildings.  Often solutions involve several subject areas sharing one class room, or standardised class room units in the playground.  This might not be the most satisfactory solution.  A standardised class room will not make the best working environment for every subject.  Annexed buildings can feel isolated from the main school premises and play ground space is a very valuable resource, especially in inner-city schools.  At Furzedown Primary School, DesignBox Architecture worked through these issues to create a purpose designed Art studio, fully integrated with the workings of the existing building, without loss to the playground facilities.

A problem of insufficient teaching space
Furzedown Primary School is a very friendly community school in Wandsworth, London SW17.  It looks small despite it being a two-form school and it has been gradually expanding since the addition of a large extension in the 1990’s.  As the school grew, space became tight and the original Art studio was unavoidably taken as a form-room.  Initial discussions between the School and the Council for a new Art studio pointed towards a prefabricated building situated in the playground.  This was not ideal because playground space is very valuable to the children and this solution would have left Art lessons disconnected and separate from the main school premises.  In addition, a standard prefabricated classroom would not necessarily make the best space for teaching Art.

A Vision for the School
The school had higher aspirations, and with this challenge to find a new home for the Art department, efforts focused on how the existing school building might cleverly support a new addition.  The existing school buildings are arranged around a central courtyard with the form-rooms opening out on to the perimeter playground areas, at ground level.  Areas linking to or sitting over the existing building were investigated to see if they would work as a potential site.  Head Teacher Ms. Monica Kitchlew-Wilson identified a flat-roofed area over the south-east wing of the school which became the home of the new Art department, called the Art Box.

The Art Box
Budgets were very tight, but the school had lots of enthusiasm and high ambitions to create something special, and something to be proud of.  The emphasis of the design concentrated on the quality of space and light.  

  • The roof lantern works to bring lots of diffused natural North-light in to the teaching space.  It has black-out blinds so the class room can be darkened for the projector and white-board.   The lighting was designed to give good light distribution across the space.  Spot lights add to the lighting flexibility with their ability to illuminate work on walls or add contrast to artistic subjects.  
  • As much wall space as possible is provided for pinning up work.  This is helped by the use of under floor heating to eliminate wall mounted radiators.  The corner windows also help to create large areas of wall display space without compromising quality of light.  The additional height of the roof lantern helps to make the teaching space look more spacious and open.  
  • The teaching space is much larger than previous rooms used for Art and it has all storage and washing facilities directly connected to the main studio space. 

Building over the existing premises enabled the new Art Box to be fully integrated in to the life and operation of the school.  The existing ground floor corridor links to the new development with a stairwell set in to a remodeled store room.  An adjacent platform lift also allows wheelchair users to access the upper floor.

Because of the tight budgets, the external face of the new building has a simple render.  We added the signage saying 'artbox' to identify the new addition to the school.  It is a playful reference to the Bauhaus Dessau.  Using the same font but lower case, it signifies a small building for small people (children) but with big ideas!

The construction of the Art Box
At the time of the Art Box construction, the school was celebrating its centenary.  It was important to ensure that the Art Box would look neat, purposeful and make a confident addition to the school, without too much disruption to the existing premises.    

The construction site was difficult to access.  Deliveries could not be made with anything larger than a transit van.  The only vehicle that could access the site was fork-lift, so the poor construction crew had to labour without a crane. 

Although the build was programmed to make best use of the school holidays, some construction still had to take place during term time.  To ensure disruption to the working school was kept to a minimum, as many building components as possible were prefabricated off-site.

  • External walls and roof were made from structural insulated panels (SIPs)
  • Internal walls were made as prefabricated timber cassettes 
  • Windows were delivered as fully finished and glazed assemblies, including the glass-to-glass corner units

The use of prefabricated components reduced the number of site processes required to construct the building and the extent to which materials had to be cut on site.  This greatly helped to reduce the level of disruption to the school.

Our Architectural Practice
The feedback from the teachers and children on the addition of the Art Box has been incredibly positive.  The space is a real hit with everyone and the amount of Art work being produced is phenomenal.  Encouraged by this enthusiasm, it has become a key aim of our design practice to specialise in similar types of projects:  To 'add value' to school buildings and create fun and enjoyable working spaces for children and teachers.  For small to medium sized school extensions and refurbishments, time and consideration needs to be given to ensure that proposals compliment the school and provide the best working environments possible.  This can be difficult to achieve, especially with tight budgets but we feel it is an essential consideration for any school.  We are currently working on new school projects, and look forward to our next challenges.

In her letter to parents, Head Teacher Ms Monica Kitchlew-Wilson wrote:
'It was sensitively designed by Phil Wells, one of our parents, who spent a very long time really finding out what would work best for us. He has delivered a beautiful purpose built block that all of the children (and staff) enjoying using. Thanks to Phil, we are extremely grateful.'
School website home page Autumn Term 2012

Additional posts:
For our article on classroom refurbishment, see 10 Ways to Revitalise Your Classroom

For notes on the feasibility of extending upwards, over existing buildings see our post Up on the Roof 

For additional notes on the design of the Art Box, see our post Art Box Design

For more information on DesignBox Architecture, please see our website