Wooden temporary market hall made of Kerto LVL

Östermalm’s old market hall from 1886 in Sweden is known for its traditional prestige among its committed customers. In 2012, the well-established rendezvous in Stockholm’s finest district was facing a crucial need for a complete renovation, and the city sent out an open invitation for the refurbishment project.

The project included a fundamental risk: how could it be guaranteed that the entrepreneurs of the old market hall could carry on their business without losing their settled customer base and that the well-established restaurants and shops would return after the years of evacuation?

The solution for this challenge was found in a temporary building, made of Metsä Wood’s Kerto® LVL (laminated veneer lumber), where the entire offering of the old market hall was maintained under one roof. What was not foreseen was the tremendous popularity of the temporary market hall which was built in the same square.

The Östermalmshallen brand is valued for three things: it’s location, the distinct character of the building and extremely good food.

Mark Humphreys, the principal architect

A 100% temporary building with wood

One of the most well-known architectural agencies in the Nordics, Tengbom, saw the potential in the exceptional circumstances. As part of the refurbishment project they designed a concept with a temporary wooden building that was built right next to the old hall. Afterwards the building is easy to demount and reuse somewhere else.

“The Östermalmshallen brand is valued for three things: it’s location, the distinct character of the building and extremely good food. We needed to rethink the whole concept - to keep the brand alive”, the principal architect Mark Humphreys says.

“A standard solution for a temporary building would have been a tent with an aluminum or steel structure. But this solution would not have suited the prestigious brand. And that is what we needed to enhance”, Humphreys continues.

Tengbom also wanted to promote sustainable construction and wood was a natural choice for that. The fresh-looking modern market hall does not appear as temporary construction at all, but that’s what it is -  a 100%.

Clever, economical and lightweight wood

Clearly, Tengbom could not argue for a large budget in a temporary construction. There is also an underground station beneath the square, so a big foundation would have been out of the question anyway. Metsä Wood’s lightweight Kerto LVL offered high degree of prefabrication and therefore suited well for the construction project.

The temporary market hall is an interesting combination of wood, glass and plastic. All these materials are lightweight, easy to work with and affordable, i.e. most suitable for the temporary use. The industrial, cold and grey plastic surface comes to life with wood’s warm and human look and feel.

The architecturally very sophisticated building looks rather rough up close. However, the mission was accomplished as the materials used are very affordable, but the ensemble looks polished and expensive, just like the neighborhood around it.

Prefabricated modules and fast installation

Tight time plan doesn’t mean you can’t do great architecture. Tengbom took the opportunity to actually build a new building in the city center as a very rare but special challenge.

Their concept for the temporary building is based on a modular system, which is easy and fast to erect and demount. It took only five weeks from the start for the external envelope to be erected.

The area for the temporary market hall was very limited. And there are passengers walking right by its sides. A couple of the restaurants were very strategically located by the glass façade so that people can see in and out and the seating areas bathe in the daylight. Rest of the street level façade is built from vertical plained pine battens, offering “dark space” e.g. for storages and incoming deliveries.

Load bearing structures and bracing

The building’s roof structure consists of Kerto LVL beams and glulam columns. The beams are placed in a grid structure, which is a strong shape, but makes the construction appear lighter and requires less material. The set-up of the roof grid puts the pressure on the connections, which need to be strong enough for the loads. The roof above the grid is made of bearing wood fiber elements that also are sound absorptive. The well-functioning acoustics is actually one the best successes in the project.

The strong columns support the loads from the 1,2 meter long main beams. The load from the roof is taken by the wood fiber elements – the outer walls don't transmit any of the vertical loads. The long sides are braced with the wall panels, which are fastened to each other. The short ends, one made mostly of glass, have a steel diagonal to handle the bracing.

Similar insulation standards apply to the temporary market hall as to permanent buildings in Sweden. The plastic used in the building is multichannel plastic, where there are lots of air pockets inside. The material has very good insulation value. The plastic parts are completely prefabricated and they are air-tight, water-tight and insulated naturally. Also the glass in the windows is insulated glass.

To keep the market hall warm in the winter, there are electric radiators, which are the same size and shape as the glass walls. There are also separate air handling units that push out fresh warm air.

Fire safety

The fire safety of the temporary market hall is handled with a fire protection treatment of the wood products. The beams are painted with transparent fire retardant applied on site and the plywood of the desks and walls also have a flame safety treatment. The floors and the columns  up to three meters were covered with gypsum plasterboard. No sprinkler system was needed, but fire alarms were installed in the grid tops rather densely as the 1,2 meter high beams make the grid pretty deep.

Temporary construction  became a sight

Being about 60% of the size of the old one, the temporary market hall in Östermalm became bright, luminous, modern and a truly invoking place with stores and restaurants. Offering longer opening hours it is accessible also in the evenings, and has attracted new audiences without losing the regular ones. So far the market hall has had over 55 000 visitors per week – that is almost a 100% increase compared to the old hall.

The tenants, the entrepreneurs at the old market hall, have increased their turnover even though they all have less square meters for their business. The temporary hall has become a well-received attraction by tourists and also media has raised interest in the building worldwide.