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Stadthaus: A Process Revealed

by Mel Starrs on July 20, 2009

in Case Studies

An advantage to living in London during the week is the wealth of events, exhibitions and ‘do’s’ available to me, generally for free. Last week I took the opportunity to head to a very well attended event at Building Centre on Store St with standing room only.

The talk was on the Stadthaus, the tallest residential timber engineered building in the world.
It is, bizarrely, located at Murray Grove, in Shoreditch. KLH were the timber supplier, architects were Waugh Thistleton, and structural engineers were Techniker. Our speakers for the evening were Andrew Waugh (architect) and Matthew Linegaugh (structural engineer).

The 9 stories are positioned on the old footprint of a pub which used to be there. The building consists of 29 flats for Telford Homes, 10 affordable and 19 private. One interesting thing to note is that despite the affordable and private being within the same block, they each have their own entrance, bin stores, staircases etc! The adjacent properties were mainly high density LA housing.

At the time of construction, concrete and steel were very expensive and there was an incentive to build quick. The solution was to use cross laminated timber entirely (not even using a concrete core which would have lead to settling problems). This was a major change in the beam, column, slab mentality. The structure looks rather more like a deck of cards where every wall is a beam (diaphragm).

In addition to the speed of construction, the other main advantage was getting around the GLA‘s frustrating attitude to renewables. GLA proposed GSHP which would have required a basement plantroom. The team felt this was too costly, and also not in the real spirit of carbon reduction. They argued, successfully, that the timber construction had a much greater impact.

The maths went something like this:

  • Timber stored carbon 186 tonnes.
  • Concrete 130 tonnes emitted.
  • So saving is 300 tonnes saved.
  • 10% reduction is equivalent to 210 years.

Amazingly, the GLA agreed.

Comparing the program to an equivalent concrete building: 47 week program vs 72 weeks. Concrete would have been 4 times heavier and dense resulting in a much greater use of resources. During the Q&A the question of thermal mass was picked up and the answer from KLH was that we don’t currently properly understand thermal mass of cross laminated but research is currently being done. POE is just about to commence – it will be interesting to see how it performs in practice.

Apart from the timber structure the rest of the build was remarkably conventional. Follow on trades didn’t come on site until timber was up – could have got even better time savings. Electricians loved it for first fix – a nail gun and a pair of stilts and the job was done in a fraction of the time compared to drilling into concrete. Heating was via a floating screed floor with uderfloor heating.

From the Wood Awards:

The facade was created by recording the changing light and shadows formed on the empty site by the surrounding buildings and trees; the pattern was captured through a sun-path animation. The resulting image was pixilated, picked up, stretched and wrapped around the building. The exterior cladding forming this pixilated image is made up of over 5,000 individual panels across the building in three shades: white, grey and black. The 1200×230mm panels are manufactured by Eternit and made up of 70% waste timber.

The building was pre-Code for Sustainable Homes, but being partially affordable housing was built under Ecohomes. It started at an ‘Excellent’ rating but  cost savings during design resulted in a ‘Very Good’ rating.

The build costs were thought to be approximately 10% less than the equivalent concrete structure, but much of that saving is related to time and labour rather than capital cost.

For further information a book is available: A Process Revealed / Auf dem Howlzweg:Stadthaus (which I resisted the urge to buy myself – but it’s a very handsome tome).

Whilst the engineering is undoubtedly a huge success, there were a couple of points which maybe let down the ‘social’ aspect of the project – namely the demise of a pub (which may well have been a den of iniquity, but I have a soft spot for pubs) and the separation of the affordable/private common areas. Both, no doubt, commercial decisions.  Apart from these minor niggles, a successful project.

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