As part of a pilot project for wooden construction, the City of Espoo is building a new school and daycare centre in the Tiistilä district. The use of wood as a building material is in line with the city’s strategic goals of sustainable development and carbon neutrality. This new building will be ready for study and play in August 2024.

Text: Arto Aho (Arkkitehtitoimista LPV), Juha Kemppi (Sweco) ja Samuli Torkko (YIT)

Read the article in Finnish here.

In terms of building mass, the Tiistilä school and daycare centre clearly carries the look of a public building. The architectural design enlivens and brightens the large mass both inside and out, with the grey-treated woodwork of the façades contrasted by colourful entrances and varied window openings. Pastel hues in the wooden interiors give the learning environment a calm feel.

In the design phase, the project had the added challenge of meeting the city’s need for maximum cost-effectiveness. With a cost estimate of 40 million, the school’s price per square metre is indeed lower than average for educational facilities in Espoo. This took considerable functional optimisation, including a compact, box-like shape with short connections between the various spaces. The main entrance connects directly to the heart of the building, which provides easy access to the building’s other spaces. There are semi-public spaces around this heart that can be used by everyone. A more private zone is on the building’s outer perimeter.

All spaces are jointly used by the elementary school and the daycare centre and shared as needed. Common spaces include the canteen and gymnasium with their ancillary spaces, staff facilities, and spaces for practical and artistic subjects.

Technical solutions

The building’s main frame consists of LVL open box rib slabs supported by load-bearing wood-frame walls, in addition to GLVL beams and columns. Wooden ribbed slab with thermal insulation was used for the ceiling structure, which is topped by the skeleton frame walls and ribbed slabs of the attic and roof.

Solutions departed from the main structural system for areas like the gymnasium, for example, where glulam pillars, ridge beams and glulam ribbed slabs form the load-bearing structures. Glulam has also been used for the building’s two stairwells. The glulam structures will be visible in the final building. For overall stability, the skeleton-framed wooden walls are stiffened with panels and the intermediate and upper floor slabs made from LVL transfer horizontal loads to the walls. LVL panelling is used to brace the vertical structures. An expansion joint divides the building into two blocks with their own independent bracing.

Construction project

Design work began in September 2020 once the contract for the project’s development phase had been concluded. The project management contract for the production phase was signed in December 2021.

The previous school building was demolished between January and May 2022, and construction of the new building kicked off in April 2022. The installation of the wooden frame began in August and is estimated to be complete in April 2023. The entire building is projected to be ready in July 2024.

The largest task on the site is the construction of the wooden frame, encompassing everything from the hollow core slabs to the top surface of the plywood roof. The pre-fabricated elements include not only the building frame, insulation and vapour barrier but also the façades, windows and sills, inner surface panelling and opening reservations. All wooden elements are installed under the cover of a weatherproof shelter, which is split into two parts due to the size of the building. In the spirit of the project management contract, the designs are a cooperative effort by the client, users, and contractors. Thanks to this cooperation, the project has TEKIJÄT | CREDITS not veered off budget despite current challenges in the market.

Key lessons of the project so far:

• An increased amount of pre-fabrication requires increased accuracy in design, such as in the placement of opening reservations, etc.
• Light wooden elements can be installed with Hiab loaders under a weather shelter.
• Lighting is excellent under a weather shelter, and conditions are easy to control.
• When the weather shelter was connected to the frame for support, this gave the building a considerable amount of temporary supports and structures.
• The installation tolerances of wooden elements could be decreased even further, provided that installability is properly taken into account in detailing.
• When it comes to providing sufficient support for building technology, the open box rib slab structure and the sound and fire insulation plaster underneath it pose challenges that must be taken into account in the design phase.

CREDITS

LPV arkkitehdit Helsinki, better known as LPV, is an architectural design company that provides a full range of services. Our projects have included schools, educational institutions, residences, public buildings, office and commercial properties and the renovation of listed buildings. We provide a wide range of architectural services, including project planning, building history investigation, and data model coordination in addition to building design.