Saturday, 21 September 2013

Glulam/CLT - what's the difference?

I was recently talking to a colleague about my experience working for a cross-laminated timber (CLT) manufacturer and how I felt that laminated timber was going to be the material of the future. He assumed I was talking about glulam, but actually glulam and CLT are different products. To help understand the difference, here is my explanation of the two.



cross laminated timber floor

CLT stands for Cross Laminated Timber which basically refers to the layers of timber (lamellas) that are glued perpendicular to their adjacent layers - cross lamination. This characteristic of the product gives it strength in two directions rather than the one as is the case with glulam. This is the main difference between the physical nature of CLT and glulam. CLT is engineered timber that is structural and is used for walls, floors and roofs (see my previous related blog posts on high rise timber and pre-fabricated architecture). The thickness of panels varies from minimum 3 layers up to 7 layers of timber and the sizes of panels is limited by transportation. CLT can be manufactured with varying grades of finish with a base grade (suitable for cladding) to a high quality exposed internal finish. However, note that the product cannot be left exposed on the exterior due to its water permeability and thus must be clad on the outside. This is in contrast to concrete, for example, to which the product can be compared in terms of its application, but concrete can be left exposed to the elements.

CLT is a sustainable product (as long as the timber is sustainably sourced) that uses far less amounts of clean water than concrete production and it is also a renewable material. As long as the timber is not burnt it retains the carbon within it. In fact the least sustainable aspect CLT manufacture is its transportation since the majority of CLT is manufactured abroad (mainland Europe and Scandinavia). The greatest benefits of the material are its time saving on site due to off-site manufacture, the dry nature of the construction process and the precision and accuracy due to pre-fabrication. However, this also requires greater time pre-construction for the co-ordination of design. As all openings, including service openings are cut in the factory, these all need to be fully co-ordinated and incorporated prior to cutting. Minor changes can be made on site, however, these are of course time consuming and the finished cut can never be as clean as that machined off-site. CLT is also much lighter than concrete so small elements can be manually handled.



glulam beam cross section

Glulam is also machined timber but it differs from CLT due to the lamination of the layers (lamella). Glulam stands for 'Glued Laminated Timber' whereby layers of timber are cut in the same grain and jointed and glued together. This gives the glulam strength in one direction and for this reason glulam is predominantly used for structural beams. The advantages of glulam are that it is lighter in weight than steel or concrete and has a higher strength to weight ratio than steel or concrete. It provides flexibility with curved as well as straight forms and is often chosen over steel or concrete due to its softer/ warmer appearance. This is particularly important within residential settings, for example. The biggest disadvantage of using glulam would be that often structural members are larger than would be the case with concrete or steel and this can be problematic in restrictive spaces.

Despite many people being wary of specifying timber due to the performance of wood in fire, both CLT and glulam perform well. This is because the laminated elements of the products make it very difficult for the timber to go 'up in flames' as it chars each layer slowly. It does not deform as steel does under fire. Specification of CLT and glulam is already increasing in the UK and as the construction industry gains confidence in the material, I believe it will become a leader for structural applications due to its sustainable nature.

For anyone interested in learning more about CLT should definitely read the blog by Timber consultancy TimberFirst which explains the characteristics and applications of CLT.

Sunday, 30 June 2013

Reduce, re-use, recycle - the CT Caravanserai

I recently attended a lecture at Ash Sakula Architects' offices given by Carolyn Steel (of Hungry City fame). It doesn't really have anything to do with the post you're about to read, but I met some interesting people who invited me to a pop-up space called 'Canning Town Caravanserai' (CTC). I had heard the name before through Open House 2012, but was unable to attend and now here was the perfect opportunity to make a visit.

Ash Sakula were preparing for their first major event at the Caravanserai (meaning a roadside inn where travelers could rest on their journey) and when I visited earlier in the day, people were busy preparing for the evening. Designed to be a social/ trading/ training/ gardening/ eating space, there's a lot it's trying to achieve and it's made a good start. Visiting during a quiet period, you get the opportunity to look at the structures, which have a simple yet contemporary design. Designed and built by volunteers, it shows the passion behind the cause and the dedication of the people involved.

CTC is in Canning Town in East London, in the area where the former London Docks used to be. As one of the most deprived areas of London, there has been a lot of regeneration work here with new residential developments along the river, along with a new cable car nearby with a route across the river to north Greenwich. Walking out of Canning Town station there's nothing in the area that really draws your attention and unless you have somewhere to be, there wouldn't really be a need for you to stop here. Perhaps its fitting then that the CTC is located a few seconds' walk from the station on a narrow site adjacent to the main road.

Ash Sakula won the Meanwhile London competition for this space to be occupied until a developer takes ownership and develops it in 4 years' time. The council (Newham) were looking for the space to be used prior to its development and what Ash Sakula have proposed seems fitting for an area, which frankly, needs a bit of social uplift.

The Canning Town Caravanserai proudly calls itself the 'new trading post in East London' and it's designed as a social and trading space with a community focused agenda. As is common with many such 'bottom-up' initiatives, the initial funding for the project came from 3 grants in 2012 amounting to £16,000 with a further £10,000 in 2013 through fund raising activities. Structures on site utilise materials found through building networks and upcyclers and are built by volunteer interns who gain valuable experience through the process.

CTC is a space for the use of the community. As it's still a fairly new project, community involvement needs to be developed. Cany Ash of Ash Sakula currently manages the space, which takes up her personal time and so she hopes to get local volunteers involved in the management. A year has already passed since the architects won the competition and so it is important for the space to add some value to the local area prior to it's end in 3 years' time when the structures on site will need to be dismantled (to be re-used hopefully on another Caravanserai elsewhere). These will be replaced by a supermarket and more housing. It's a shame that such initiatives are not given the opportunity to develop since the area already lacks spaces for community use and with another residential block going up this problem may still remain for some time.

the theatre space at CTC
It's interesting to visit projects such as CTC, since it shows the dedication required for such bottom-up projects. The funding is always an issue where local councils are reluctant to provide financial aid for the development of social spaces, the focus being on meeting targets, such as for housing. But the social factor is important too. Management is the second issue and probably the main reason for why such projects may not be so successful, since community ownership is an important element. 

What is really fantastic about this project is the dedication of the management and the volunteers who have helped realise the project. The 'reduce, re-use, recycle' ethos of the initiative is commendable with the extensive use of salvaged materials, which add a ruggedness to the kiosks. At the moment, the space is still developing and many kiosks lie vacant, waiting to be occupied. It's still early days for CTC. However, as the space develops to be fully utilised, I hope to see it become a truly community managed space for the benefit of the local area. 

the cafe at CTC
A special thanks to Cany Ash for contributions for this post. For updates on CTC, check out their Facebook page.

Sunday, 26 May 2013

There's nothing slippery about the Slip house

slip house
I don't usually go to Brixton (South London) much, in fact I've only been once, on a dull grey Friday afternoon. It's a good thing I was going to see something quite interesting! Another event as part of Green Sky Thinking week was a tour of and a talk on Slip House by Carl Turner of Carl Turner Architects. Completed at the end of 2012 to almost Passivhaus standards, I was interested in learning about the lessons from the first 6 months of occupancy of this super sustainable building.

Turner was the architect for this home and studio for himself and his partner. The couple chose one of 4 empty plots in a gap of Victorian terraces for the building. As a brownfield site the project was already heading in a positive direction in terms of its 'eco' ethos and the main concept is to provide an affordable flexible sustainable home within an urban environment. This was to come not only from the materials and the method of construction but also the maintenance through technology installed within the building.

The design of the house is a series of staggered stacked boxes that jut out as required to achieve the functional requirements for the spaces within - primarily views and sunlight. This 'upside down' house has the living and eating area on the second floor (where there is easy access to the rooftop terrace), the sleeping areas on the first and a flexible space at ground level. Currently this is being used as the practice's studio but in the future it offers the flexibility either to become an extension of the home or a stand alone apartment.

Walking around the house it's clear that a lot of thought has been put into the design with clever detailing to conceal edges and connections. The perimeter walls are load bearing thus freeing up the space within to allow flexibility. Lightweight partitions divide up the spaces as required or can be knocked down in the future to change the configuration. There are also lots of sliding panels and built in storage spaces that not only hide away the clutter of everyday living but also allow division of space in some areas. On the ground floor, for example, there is a whole 'pod on wheels' with a workstation and storage that can be wheeled around as required. In addition to this almost all doors are sliding which makes a big difference in space saving. Although not generous in space standards, the use of these mechanisms allows the house to be perceived as spacious.  

The structure of the building is steel to allow for future flexibility. When the project was first on the drawing board (5 years ago) there were discussions around using cross laminated timber (CLT) for the load-bearing structure. However, at the time there was not as much knowledge on the material and it was more expensive than steel. It's a shame that it's not built of timber since perhaps that is one of the things that lets down it's eco credentials, well that and the concrete floors (but we'll come onto those shortly). However, despite the above, the house makes up for it in many other ways. The building is super insulated with thick walls and is airtight (almost up to Passivhaus standards). It's important to note here that simply super insulating the building will not improve the energy performance. If the building is not airtight then the heat will escape thus rendering the extra insulation completely useless. The floors are composite concrete with a pre-cast slab on the underside and in-situ on top. Although very unsustainable in its embodied energy, concrete has advantages in terms of its thermal mass and it's also a great sound insulator thus preventing the need for any additional insulation to be laid on top. It is able to retain heat to reduce mechanical cooling demand. The walls of the building are pre-fabricated timber sandwich panels - OSB boards with insulation within. These use waste material and can easily be re-used. The windows are triple glazed to Passivhaus standard thus keeping the weather out and the heat in! 

Apart from the material nature of the building, there is technology in place that plays a part in the use of the building. The rooftop terrace serves as much needed private outdoor space but is also where the PVT (photovoltaic thermal) panels live. These panels combine the abilities of solar panels with solar water heaters to provide both electricity and hot water using one product. This saves space and is also more efficient. The terrace also helps in collecting rainwater for the rainwater harvesting and the use of water is controlled within the building. All the technology is integrated well into the building with the mechanical equipment sitting hidden away behind one of the bedroom's built in wardrobes. These are not 'add-ons' but actual design decisions for the house.

PVT panels on the roof terrace
This house is beautiful with crisp detailing throughout where extra effort has been put into concealing connections. The house was designed to achieve Code for Sustainable Homes (CSH) level 5 but in reality it is becoming difficult for it to achieve this. This comes down to a problem with the assessment method. CSH measures according to set parameters and even if you provide something over and beyond these parameters, if they are not on the list and the box can't be ticked, then it cannot be achieved. In this way there are various things designed and installed in this building that are not on that CSH list and therefore the building is falling short of achieving this target. It's a real shame that methods of measurement such as these that are meant to be there for achieving high quality sustainable architecture are actually failing in recognising the really exemplary buildings.

I like the house, its cleverly designed and is contemporary and functional. The deep plan could have been problematic in terms of getting light into the spaces but this only seems to be a problem at ground level. On the upper floors large windows and rooflights let in plenty of light making the space feel bigger than it is. However, despite my admiration for the design and sustainability of this house, I'm a little disappointed by its integration into the neighbourhood. Although the house sits within the footprint of a terraced house, it seems very dominant and a little out of place. In addition, this building has it's own private gate which has monitored access and seems a little fortress-like for the neighbourhood. Maybe this is because it is also an office - I don't honestly know. But the form and appearance is a contrast to it's neighbourhood and it would have been nice to see it working better with it's context. I don't have a problem with the aesthetic of the building but I do feel perhaps it's not appropriate for this location, but that's just my opinion.

Tuesday, 30 April 2013

Greener than green - 5 Hanover Square

5 Hanover Square
As part of Green Sky Thinking Week I attended a seminar and building tour at the recently completed 5 Hanover Square in central London. Designed by Squire and Partners, the site is located within Mayfair's conservation area with listed buildings surrounding it. This in itself was a restriction. To add to that the client (Mitsui Fudosan) drove the sustainability agenda for this building demanding 10% renewables. 

Completed in 2012, the £26m mixed use development achieved BREEAM excellent for the office building and Code for Sustainable Homes Level 4 for the adjoining apartments. It looks like any other office building except it throws in as much sustainability into a building as it can given the site constraints:
  • photovoltaics on the roof - these are angled at the optimum 30 degrees and are cleverly located to conceal the roof plant. They are also installed on the mansard roof.
  • living wall - this is installed on the north-east (back) facade of the building and is fed by rainwater that is harvested and filtered
  • post tensioned concrete slabs - these reduced the amount of concrete used since the slabs could be thinner and required less reinforcement
  • 40% of the cement content of the concrete was replaced by GGBS (ground granulated blast-furnace slag), a by-product of the iron ore industry
  • 25% of the aggregate content for the concrete was replaced with stent, which is a by-product of the China Clay industry
  • 97% of waste was reused or recycled
  • LEDs used throughout the building
mansard photovoltaic roof

photovoltaics on the roof
From the above list it's clear to see that there has been a lot of thought put into the reduction of energy use for maintenance of the building but also the embodied energy of the materials used. Simply looking at the concrete content alone we can see the significant carbon reduction by the use of waste products. This makes me think that concrete could be less of an evil than first imagined, if the correct 'ingredients' are used. 

Apart from the material carbon savings, there are perhaps more renewables that could have been employed on site. However, the location of the building is very restrictive. Wind turbines were considered as an early solution but testing on site proved to be less successful and therefore photovoltaics were chosen. The site's proximity to the Crossrail tunnels also prevented any technologies such as ground source heat pumps which could have otherwise been incorporated. 

This building is one of the few sustainable office buildings I have visited and in appearance it looks much like any other office building. This could be a good or a bad thing, depending on your personal opinions. I have the view that if a building can look like a 'normal' building yet out-perform and in a more intelligent way, then all the better. But then I also believe that the building should portray its 'green-ness'. It's a shame that the living wall is on the back facade hidden from sight. I would have preferred for it to be a prominent feature of the building and it's disappointing that it's not. Perhaps this was a restriction of the conservation area...

living wall
The office floors are bright allowing good views out to the city and also letting in plenty of natural light. The flats latched onto the end of each floor are somewhat disappointing as spaces. Although thought has been put into the specification, the stair treads are already chipping and the spaces are small and dark. I don't think it would be my choice of a place in the city. 

Despite my minor criticisms above, this project should be judged on its merits. It's a building that is working hard to be sustainable and so far it seems to be doing well. I guess the real test will come once the building is fully occupied and operational and whether it still performs as it's designed to.

Sunday, 17 March 2013

The importance of the big C - Context

Ringroad (Houston) - image by Bas Princen
Whilst flicking through an old Domus edition I came across the image shown above which made me stop and wonder. It wasn't so much the photography that amazed me but the hideousness of the architecture presented here, I mean what exactly is this building trying to be? The thing that annoys me about this photo is the fact that this building is completely context-less, there is absolutely nothing that the building is relating to.

the deserted New South China Mall (image:
Following this I stumbled across an article I recently read on CNN about an abandoned Chinese mall which is now a "ghost town". The New South China Mall in Dongguan, China is the largest mall in the world based on leasable area. The idea of Chinese noodle selling billionnaire Alex Hu, was to build the largest mall in the world in his home town of Dongguan. It was meant to attract over 100,000 visitors a day, but 8 years after completion it is still as dead as the day it was built. The mall was to provide 2,350 retail spaces along with a cinema, restaurants and even roller coasters, but on completion in 2005 it was 99 per cent unoccupied! What was the problem?

Location, location, location!

Dongguan is a city with a population of over 10 million people, but the majority of these are migrant workers who work long hours in factories manufacturing products that are exported around the world. It's a city of poor, hard working people who lack the time and money to spend in such malls. But let's imagine for a second that they do, how would they even get here? The mall sits out in the middle of nowhere with no access by foot or bicycle and there are no major transport links, no airports, no infrastructure, so how are you meant to access it? If the people of Dongguan are unable to reach the mall, what hope do others have of accessing it? And herein lies the problem with this development - there is no understanding of context.

the deserted New South China Mall (image:
the deserted New South China Mall (image:
I find it frustrating to come across projects that are built without any understanding of the surrounding context - the context of the land and the people. New developments should be designed with thought given to its target user and how they would use the development. If there is no target user then surely there is no need to build?

construction outside Xian, China
Whilst I was in China I came across so much construction everywhere I went. These 'ghost towers' were cropping up all over cities and outside and around cities. But they didn't relate to anything. Context is so important for buildings to last and it's only a matter of time before these context-less developments are converted to rubble. How long can China really continue with the attitute of 'if you build they will come'?? The New South China Mall, for example, after 8 years is still not used as it should have been and the worst thing about this kind of development is that all those resources - the hours and the materials and the energy that have gone into its construction have gone to waste.

Perhaps this type of thoughtless construction is more common in China, but I have seen many buildings elsewhere that are just as bad and I cannot understand how people can forget about context.  It's not only the relation a building has to its immediate neighbouring buildings but it's also about the neighbourhood (in the broader sense). It's about addressing the needs of the local people because surely if there isn't a need, why build it?

Another example of an out of place building - the CCTV tower in Beijing, China

Sunday, 17 February 2013

Paper bricks as a building material

Two Nagpur (India) based researchers have developed a kind of paper brick that can be used for internal partitions, temporary structures and perhaps structures in earthquake prone zones in the future. It was a visit to a paper recycle mill by Sachin Mandavgane and Rahul Ralegaonkar which really got the ball rolling. The researchers from the Visvesvarya National Institute of Technology in India found that the sludge waste from the paper recycling process was being dumped in landfill and felt instead the waste material could be put to better use.

To produce the waste paper bricks, 90% recycled paper mill waste (RPMW) is mechanically mixed and pressed with 10% cement and placed into steel moulds until the moisture has drained. The bricks are then left out in the sun to dry. The semi-dried brick is then compressed further to remove more moisture and is then again left out in the sun to dry until solid. The end product is a recycled paper brick that can be used internally.

There are obviously drawbacks of the product which are mainly related to the material - paper - itself. The brick has excellent absorption qualities and thus retains water so cannot be used outdoors. The team are currently working on waterproofing the material so it can be used for external use. However, there are also great advantages of the product such as them being half the price of normal bricks and much lighter. The simplicity of production also means that they can be manufactured fairly simply using local labour. 

For more information see here

Tuesday, 12 February 2013

Oil can canopy

the oil can canopy (image: Sundeep Bali and Adam Rooney)
India is known for its can-do and mend attitude and so it's not a surprise to see an art initiatives such as Jugaad created by artist Sanjeev Shankar. Jugaad is a canopy made up of hundreds of re-used oil cans strung together and operated via pulleys and cables. I've previously blogged about Mumbai's recycling hub within Dharavi, and this isn't something that just happens within Mumbai but nationwide. It's the poor population's way of making money and a way for India to reduce its waste. Jugaad takes this activity a step further by using the re-used oil cans and converting them into an art installation for the wider population to see.

The installation was a way for Shankar to "interrogate the teetering ecology of the city through the prism of contemporary art". It is a truly ecological endeavour since local people from the village of Rajkori, just outside of Delhi, were asked to collect the empty discarded cans and to construct the canopy. It was a way of engaging the community. Ultimately the canopy is a piece of art and its beautiful yet still being functional.