Engineering a new identity for Coventry museum

Glulam makes another impressive mark
By John Cotton

Architects Pringle Richards Sharratt has used Finnforest Merk’s expertise in engineered timber solutions to deliver two crowning elements for the redevelopment of the Herbert Art Gallery & Museum in Coventry.

The scheme consists of two new galleries, a state-of-the-art history centre, an underground city archive and a 50m long public covered arcade. Architects at Pringle Richards Sharratt were challenged with engaging the existing gallery with the public spaces around it, including the ruins of the old Cathedral and imposing new Cathedral, which sit opposite the site.

The solution is a partially glazed gridshell arcade formed of glulam. The gridshell is designed to reflect its Coventry city centre context as a civic space, by resembling the interior of the City’s cathedral roof and extending the presence of the gallery towards this famous landmark.

“The concept for the arcade was to turn the rear of the building into the front. At the same time we needed to establish a pedestrian route connecting the arcade with the exisiting entrance to the building,” explains John Pringle, Principal at Pringle Richards Sharratt.

Meanwhile the 342sqm History Centre within the redevelopment of the Herbert Art Gallery & Museum has been topped by a curving glulam beam and solid timber panel structure, which is supported with spruce columns. The mono pitch roof curves upwards to meet the edge of the arcade, transforming into the diagonal gridshell.

Glulam from Finnforest was used to create both the gridshell structure and vaulted roof. It was selected for its exceptional strength and lightweight properties and is especially suited for use in the load bearing structures of buildings where architectural beauty is being sought in structurally challenging designs. Meanwhile the aesthetic qualities of the timber mean that exposed beams and the structural system become a point of architectural interest in their own right.

Because Finnforest sources all its timber from PEFC or FSC certified forests, and ensures that an independently audited chain of custody is adhered to at every stage of the material’s processing, engineered timber is an ideal choice for architects seeking to contribute to the sustainable agenda.

Photos by Charlotte Wood Photography

More information: www.finnforest.co.uk

Architects should have designs on timber frame

The doubts are overcome
By Mike Cruickshank

Every so often, it becomes clear that a technology’s time has come. The doubts are overcome, the arguments are won and the benefits become obvious and undeniable. At this point, the technology becomes an industry standard.

This is very much the stage timber frame construction is at. Despite rearguard actions by proponents of traditional brick and block construction methods, timber frame now ticks the boxes in so many areas – from sustainability and carbon footprint to labour costs – that the real surprise is that anyone still builds by other means.

Why should developers and the industry persist in building on sites which are wholly at the mercy of the weather and indifferently-skilled labour, when the opportunity exists to fabricate off-site in the controlled environment of a modern, high-tech factory?

But as timber-frame becomes increasingly dominant, is a different mindset now required from architects? After all, timber frame construction not only maximizes flexibility and ease of construction but takes full advantage of potential standardization to reduce costs.

Architects have not exactly been widely encouraged by developers to introduce bold new innovations in commercial house construction of late, but the combination of a new political will to increase house building and the limitless possibilities of timber frame should put them back into the driving seat when it comes to influencing the built environment.

ON-LINE DEBATE

Computer-based design in an architect’s office can integrate seamlessly with the engineering and manufacturing systems and highly automated plant in a modern timber frame factory. The architect can engage in online discussions with the manufacturer as the project progresses and design out potential problems before the job reaches the site.

The system takes weather out of the equation and superstructures can be erected quickly, efficiently and accurately – reducing sub-contractor costs and taking the guesswork out of pricing.

Getting the manufacturer involved in the design process at an early stage makes sense at many levels, not least on costs. But the architect can contribute substantially to cost savings and efficiency by accepting minor adjustments which need not compromise architectural integrity.

The most fundamental area in which cost-effective considerations should be taken into account is the floor plan. Ideally, to reduce labour and wastage from cutting standard size plasterboard and flooring sheets – and to suit standard stud and truss centres – buildings should be designed using either a 90mm or a 140mm stud depth on a 600mm “grid”, measured from the inside face of timber frame to inside face of timber frame on the external walls.

Ceiling heights should be designed to standard plasterboard dimensions. Although non-standard panel heights can be priced to the nearest standard height up, there will still be wastage and on-site labour costs for cutting.

In the design phase of the ground floor, it is vital to consider the spans of the upper floor joists. If joist spans are designed near to their limit, it increases deflection whilst avoiding excessive spans solves a number of traditional problems, including ensuring that load-bearing partitions are positioned correctly.

DESIGNERS IN DIALOGUE

Designers, in a dialogue with manufacturers, can also benefit by standardising external door lintel heights and window dimensions. For instance, a lintel height of 2.1m from finished floor level will accommodate most external door sets and increase choice. Non-standard internal doors should be avoided.

Bespoke windows are attractive from a design point of view, but are expensive and can lead to delivery delay. It may be possible to achieve an architecturally similar effect by combining the widths of standard modules.

Using the “grid” plan referred to above will also reduce the number of trusses needed for “room in the roof” designs using dormer windows, Velux windows and stairs. Stairs themselves can be finalized at the design stage to make them fully compliant with new building control requirements.

The variety of standard skirtings and facings and the materials from which they are made – is now so extensive that there is no real need for specifying non-standard items. Once again, all they will do is increase costs and delivery times.

The technological advantages of timber frame construction are an opportunity for architects to make an impact on the urban environment as never before. If designers work in tandem with reputable manufacturers, the benefits can be reaped not only in cost and time, but in the quality of people’s lives.

Images show example of Scotframe projects

[Mike Cruickshank is Sales Director at Scotframe Timber Engineering. The company operates across the UK and Ireland from its bases in Inverurie near Aberdeen, Cumbernauld near Glasgow, and Hillsborough in Northern Ireland and employs over 200 people. Current turnover is in excess of £35m.]

More information: www.scotframe.co.uk

Boise raises the I-joists bar

By Simon Jones

Latest veneer technology

Having already led the way in helping engineered timber I-Joists displace traditional solid wooden beams from the majority of the housing market, as well as other sectors, the BCI®Joist has taken another jump forward in both performance and perception thanks to some small, yet important, technical improvements.

The new 5000-, 6000- and 6500-series joists utilise the latest veneer technology to improve the dynamics of the flange by decreasing its depth and increasing its width. This has a number of key advantages:

• in engineering terms, this positions more of the flange where it needs to be, in order to resist tension and compression forces
• for the carpenter and dry-liner, it provides wider nailing surfaces with flanges now a minimum of 50mm wide
• it improves efficiencies in manufacturing, helping improve latent capacity and ensuring competitive supply
• it is a further demonstration of Boise’s commitment to environmentally-aware man by engineering a reduction in resin requirements

Mimicking the shape and load distribution of steel girders, the joists feature a web formed from a high-grade OSB, separating flanges of laminated veneers (LVL). While the original units were stronger, lighter and easier to work with than conventional floor beams, the new variants raise the bar again.

Seen as being in step with the principles of prefabrication and off-site construction the joists enable carpenters and even multi-skilled operatives to install floor constructions more quickly, with their low weight and consistent dimensions making assembly a rapid and easily repeatable operation. Not only does the reduced weight cut the risk of back strains, the chamfered edges to the flanges virtually eliminate splinter injuries.

Utilising the BCI joists in accordance with the company’s installation instructions will avoid the cost and inconvenience associated with having to rectify the problem of squeaking floors. Stiffness is a key characteristic in the ‘feel’ of a floor and therefore, the cost effective ability of BCI®Joists to increase depth without suffering the price and weight penalties associated with conventional beams, means the range of sizes can provide economic solutions for very many commercial as well as domestic situations.

The high quality and consistent performance of BCI®Joists eliminate the need for on-site grading while the long lengths available further increase the simplicity of the construction process. Site times can be dramatically reduced by using the system and the joists can multispan in one place.

As well as easily accommodating normal residential spans, the strength of the joists provides for flexibility of the upstairs room layouts, while the joists can be combined with the VERSA-LAM® beam products to make up Boise’s Simple Framing System^TM.

The joists are straightforward to cut or trim on site using normal tools, while the provision of 38 mm diameter knock-out holes simplifies the routing of pipes and cables. Larger services can also be accommodated in the web. They are readily available through a nationwide network of distributors, normally being supplied as precision-cut, plot-specific packages, and are supported by a full design service.

More information: www.BC.com/eu

Terracotta tile claddings on Thames-side development

Scaffolding eliminated from construction sequence
By John Pritchard

Set within 10 acres of landscaped parkland on one of the most sought after stretches of the River Thames between the fashionable neighbourhoods of Chelsea and Fulham, St George plc’s award winning Imperial Wharf development provides a range of two, three and four bedroom apartments and penthouses with spectacular panoramas of the river itself and beyond. Its tree-lined boulevard also offers its residents and visitors a selection of stylish shops, bars and haute-cuisine restaurants to enjoy.

Designed by Broadway Maylan Architects, the Imperial Wharf development is being constructed in a number of phases. Significantly, its major buildings feature is the use of architectural precast concrete with reconstructed stone finished and terracotta tile faced wall panels.

When the current phase of the development is completed shortly, The Marble Mosaic Co Ltd’s run of six precast cladding work packages will have included the casting of more than 6000 units, totalling close to £7m in value. The first phase was completed for Bilfinger Berger Ltd on a supply-and-fix basis in 2005. The next three phases were completed for Carillion Plc during 2005 and 2006 and not only included the detail design, manufacture, delivery and fixing of the wall cladding panels but also the supply of precast concrete balcony units.

The precast cladding panels for the fifth and sixth phases have been and are currently being provided respectively on a “detail design and supply only” basis for J Reddington Ltd and its main contracting division Midgard Ltd.

The majority of the precast cladding panels for each phase are storey-height units that span between the floor slabs, thereby avoiding the need for secondary backing structure for their vertical support or lateral restraint. The other cladding panel types include spandrel units that face the edges of the structural floor slabs and insitu balconies. All the panels were designed to avoid the need for an external scaffold for their safe and efficient installation.

The reconstructed stone finished precast cladding panels are typically 150mm thick and match the appearance of Portland and Bath limestones. Their colours have been achieved without the need for any pigmentation by using special mixes of either Derbyshire limestone aggregate or Cotswold gravel with white cement. Their seen surfaces have been lightly textured using a controlled technique developed by The Marble Mosaic Co Ltd to achieve a notably consistent overall appearance.

The terracotta panels have been cast with red Gima tiles, supplied by NBS in the form of 25mm thick facings cut from standard tiles, and a 150mm concrete backing. All the precast cladding panels have been manufactured with carbon steel reinforcement and fixed using stainless steel fittings.

The joints between the cladding panels have been pointed with a two-stage silicone-based sealant. Incidentally it should also be noted that, with the panels being cast using grade 45 concrete mixes, they provide a robust and durable cladding material that is inherently non-combustible and fire resistant with valuable sound-controlling properties.

If alternatively specified, they could have been supplied with insulation either as an internal core or as a backing to enhance their thermal performance. The required “U” value through the overall wall section has however been achieved using an independent insulated dry-lining system on this occasion.

More information: www.marble-mosaic.co.uk

New homes for New Orleans

Safety is paramount on the levee

Nowhere is in more desperate need of a replacement housing solution than New Orleans where Hurricane Katrina struck in 2005 with such devastation. Many thousands of people are still awaiting new homes in their native city but, hopefully, the problem has come a step closer to being resolved?

A few months ago Brad Pitt and residents of the Lower 9th Ward of New Orleans launched “Make it Right”, a national multi-million dollar fundraising campaign to help at least one part of the city recover. The actor made the announcement from the site of the “Make It Right” project’s first initiative -150 affordable and sustainable homes that are being built in partnership with US multi-millionaire, Steve Bing.

The new homes’ architects who unveiled their groundbreaking designs for the community joined Pitt and his fellow campaigners.

The architects – from the USA and around the world – include Adjaye Associates, Billes Architecture, BNIM Architects, Concordia, Constructs LLC, Eskew+Dumez+Ripple, Graft, KieranTimberlake Associates, Morphosis, MVRDV, Pugh + Scarpa Architecture, Shigeru Ban Architects, and Trahan Architects.

As New Orleans is such a special city with unique traditions and lifestyles the new home designs not only have to embrace an exceptional climate and social quirks but also take advantage of this major urban revival to introduce affordable, sustainable living in a very big way. But at the same time they don’t ignore the fact that catastrophe could strike again in a region that frequently takes a heavy buffeting from one or another hurricane.

FOUR SOLUTIONS

In this brief editorial we outline just four of the architectural solutions that are rising from New Orleans’ Lower 9th Ward where some of the worst flooding and devastation took place.

The architects Pugh+Scarpa’s concept takes advantage of one of the most under-rated, but easily sourceable elements around – recycled wooden pallets. Their imperfect, rough-hewn texture aims to provide an exceptional patchwork wrapping for each home’s main structure. And, of course, wooden pallets are commercially available, cost effective and eco-friendly.

In the architects’ words, inside “this home breaks the prescriptive mold of the traditional home by creating public and private ‘zones’ in which private space is de-emphasised in favour of large, public living areas”. This is intended to “transform the way people live” from a reclusive, isolating layout towards a family-orientated, interactive space.

The home’s sustainability revolves around its orientation to control solar cooling and heat loads and to minimise its exposure to the prevailing winds. It’s specially shaped to induce natural ventilation and airflow distribution, while its high internal ceilings will encourage an “airy, spacious ambiance that’s less reliant on artificial lighting.”

IMPORTANT PORCHES

Porches always have been and always will be an essential ingredient of New Orleans homes. And the new dwellings will be no exception. BNIM’s 940sq ft, two-bedroom design suggestion is a modern interpretation of the “shotgun-style” of home that was common in the city with ample porches fostering neighbourly interaction.

Just like all of the new homes intended the city’s Lower 9^th Ward, BNIM’s solution is sufficiently elevated to provide adequate protection from typical flooding events. Its structural insulated panels and mould-resistant walls maximise efficiency, minimise waste and respond to the local climate.

Its designed for easy of construction and energy efficiency as the roof structure will be ready to receive photovoltaic panels. A rainwater cistern and portable solar energy pack form part of ‘area of refuge” so that residents remain safe in the event of future flooding.

With significant tracts of its land below sea level Holland has a lot of experience to call on when it comes combating flooding. So it’s not surprising that the designs by Dutch architects MVRDV picked up on a lot of this knowledge.

ALL AFLOAT

For example the “floating house” concept was inspired by recent new housing developments in the Netherlands where the house is on top of a concrete barge that rises when there is flooding. “Piles” keep the house in position and the front porch forms a “garage” that takes the car with it when the water level rises.

Variations on this theme are the house on top of a lift ensuring that the entire dwelling is above the potential water level. Then there is the “bent house” which rises up at both ends creating a porches font and rear. Internally is created a “valley” of platforms with living and bedrooms whilst the very lowest level becomes a water storage facility.

The Graft house design is a “bridge between the past and present”. Once again the front porch is an important feature but beyond that there are two distinct shapes. The symmetrically pitched roof at the front represents the past and the angular flat roof shape signifies the present.

The construction uses only efficient, low-energy and healthy materials with hurricane-resistant low-E windows. The design takes advantage of passive and cross ventilation lessening the use of mechanical air conditioning or heating. Rainwater catchment systems are provided.

Each habitable room has an emergency access to the roof where there is a flat area called “the safe haven”.

Images show the MVRDV’s “bent house” which rises up at each; Pugh+Scarpa’s wooden pallet solution; Graft’s symmetrically pitched roof version; and BNIM’s more traditional version.

More information: www.makeitrightnola.org/