Wooden apartment buildings in Turku’s Perno district – Goliathin Salmi

Perched on the edge of a field looking out over the sea, the Goliathin Salmi buildings are located in the lush, widely dispersed Perno residential district in Turku. Like much of the area, these buildings steer clear of an overly urban look. Rather, the terrain, landscape, yards, and views take pride of place and very much attract the eye.

Read the article in Finnish: Koy Goliathin Salmi

The Goliathin Salmi apartment buildings exemplify superior residential construction with a strong architectural identity. Elevators provide access to four storeys of apartments with small cantilever balconies. Residents can enjoy views over the surrounding forest or an open field, depending on the apartment.

Perno is a lush residential area with rolling landscapes that allow for buildings to be widely dispersed. The surrounding views and vegetation take pride of place.

From the start, this wooden apartment building project sought to fit into the area’s existing building stock. As such, it was one of the first of its kind in the Turku region. Koskisen Oy’s wooden apartment building concept served as the starting point for the design and was further developed to improve cost-effectiveness and environmental friendliness. The architectural and structural solutions adopted resulted in an excellent, competitive alternative to reinforced concrete construction.

These wooden apartment buildings are four storeys tall and have elevators provided for the residents. Exterior walls and load-bearing partitions are mainly built from large elements on a balloon frame, whereas the elevator shaft walls, intermediate floors in the stairwell, and cantilever balconies all use LVL components.

The balloon frame made possible the distinctive, seemingly random openings in the facade that give the building a strong identity that distinguishes it from its surroundings. The facade consists of pale, painted horizontal panels, which have been treated with fire retardant on the ground floor. The windows, doors, and safety features of the facade are painted to match the facade colour, with the dark grey metal sheeting adding some variety to the otherwise uniform whole. The small, projecting balconies align with the randomly placed openings to create a playful, three-dimensional facade.

In the project’s planning stage, regulations still severely limited the use of wood in interiors. The Goliathin Salmi team eventually decided to not follow the regulations in force at the time, instead leaving wood visible as a material in the solid wood stairs of the stairwell. CLT treated with fire retardant is visible on all stair surfaces except for the tiles on the actual steps. Approval for this decision required a separate, official statement from a fire safety expert.

These spacious, family-size apartments have plenty of natural light and pleasant views in two directions over the surrounding forest or open field. The floor plans are simple and linear, providing residents with the freedom to furnish their homes in a variety of ways. The building engineering solutions show off the best aspects of prefabricated construction. For example, although the fire and sound requirements for wooden apartment buildings are often challenging, the prefabricated building engineering elements that were used to construct the plumbing solutions for water connections, bathroom drains, and vertical sewers met these requirements out-of-the-box.

Technical solutions

The wooden facades on the ground floor are treated with fire retardant. Wood surfaces are only visible in the wooden stairs in the stairwell. The staircases and exits have fire class R30.

The stairwell is separated from the surrounding spaces with class EI60 partitions. Doors have at least half the fire resistance value of their surrounding structure. Apartment fire doors are single-leaf, EI30 class doors that open towards the stairwell.

The buildings have an automatic extinguishing system (minimum SFS 5980 class 2). Mains-connected fire alarms safeguard the building stairwells, with each stairwell treated as a separate entity in a series. Smoke extraction is from the top of the stairwells (a 1m2 hatch) and triggered electrically from the stairwell’s lower level.

A distinguishing characteristic of the building is its use of prefabricated building technology elements. In addition to water connection pipes and a vertical sewer, these elements include a wall-mounted toilet and the water and sewer connections for an eventual sink next to it. The solution meets the sound level and fire regulation requirements of HVAC systems as is, with no adjustments necessary. The elements were installed on top of the intermediate floor on each storey, independent of any frame-related work.

Construction project

Planning started in early 2018, with construction kicking off in May 2018. Elements were installed in July 2018, and the project was fully complete in May 2019. Design and construction were contracted separately.

CREDITS

Lundén Architecture Company is a Helsinki-based office focused on the development and innovation of the built environment, architecture and urbanism. Founded in 2008, the office’s unique approach is shaped by the experiences of over 300 projects to date. The LAC organization is structured as a cluster of studios, each with their individual focus and area of expertise. With a rich pal-ette of knowledge and skills, the studios support and inspire each other to develop and excel in their work. At Lundén Architecture Company, the internationally diverse team shares one vision – to produce innovative and sustainable solutions.