Tiistilä school and daycare centre

As part of a pilot project for wood construction, the City of Espoo built a new school and daycare centre in its Tiistilä district. Using wood as a building material supports the city’s strategic goals of sustainable development and carbon neutrality.

Read the article in Finnish here.

The building mass has the distinctive look of a public building. Architectural details enliven and brighten this large mass both inside and out, with the grey-treated woodwork of the façades contrasted by colourful entrances and varied window openings. In addition to making the façade grey, this treatment also enhances longevity and lowers maintenance. Pastel hues in the wooden interiors give the learning environment a calm feel.

In the design phase, the project faced the added challenge of being maximally cost-effective. With an estimated cost 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 in the building’s outer perimeter. All spaces are jointly used by the elementary school and 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 in specific areas such as the gymnasium, where glulam pillars, ridge beams and glulam ribbed slabs provide the load-bearing structures. Glulam has also been used for the building’s two stairwells. The glulam structures have been left visible in the final building.

For overall stability, the skeleton-framed wooden walls are stiffened with panels and the LVL slabs of the intermediate and upper floors transfer horizontal loads to the walls. LVL panelling braces the vertical structures.

An expansion joint divides the building into two blocks, each with their own independent bracing.

Construction

The City of Espoo started the project’s tendering process in June 2020. The contract type was a project management contract, which included a 12-month development phase for the project’s concept and plans. This development phase included an assessment of the wood structure market followed by a tendering process to find a suitable wood structure supplier. With this approach, the chosen supplier’s own cost-effective operating methods were able to guide the structural design work and streamline the process from the start.

Construction kicked off in January 2022 with the demolition of the old school. This took about 5 months. Earthworks for the new school began in 04/2022, and a weather shelter was built to shield the element deliveries that ran from 08/2022 to 05/2023. Handover was in June 2024.

The project was a huge success in terms of the schedule and costs. This is chiefly thanks to a sufficiently long development phase, excellent cooperation between project parties, and the early on-boarding of key suppliers. The tendering and on-boarding of the wood structure supplier was a particular triumph for the project. This supplier’s contract was extensive, ranging from the timber frame (walls, intermediate floors, upper floors), exterior wall elements with factory-installed façades, windows and sills, most partition walls and their plasterboard surfaces, to the roof structure’s plywood.

On site, all frame work and carpentry took place under a weather shelter. Weather protection has the reputation of being expensive, but this project showed it to be a worthy investment in quality assurance and proper installation conditions that kept everything on schedule. The combination of the supplier’s extensive responsibility and pre-fabrication capabilities meant there was very little delay. Work inside individual frame sections could begin the moment the section was deemed stable and in compliance with occupational safety regulations.

In all, the procurement process systematically avoided restricting supplier know-how. Design requirements were provided on a general level, primarily describing the needs of the users of the procured item. This allowed the project to leverage each supplier’s respective expertise, ensuring procurements stayed within the budget.