Base Street Trio

Base Street Trio is a three family row house built from CLT in Tammisalo in eastern Helsinki.

Base Street Trio in Tammisalo is Helsinki’s first building constructed from solid-wood panels without insulation in the external walls. Built on a steep hill plot, the meticulous element design and a high quality frame product ensured a quick and smooth construction phase for the house despite the challenging location.

Tammisalo is an old district consisting mainly of small single family homes and row houses built after the 1950s. However, its history traces further back as the area was once part of the surrounding manors in the 19th century. Tammisalo is an island surrounded by the sea and small patches of forest. The area is very green with family gardens dotted with the old pines characteristic of the island.

As the city grows and needs more housing for its new residents, it wants to increase the construction density of these older, sparsely built neighbourhoods. This made it possible to build three homes on the small plot instead of the usual two. Due to the steep incline at the site, it made sense to incorporate the houses into the slope and the surrounding scree. This principle then evolved into the idea of laying out the individual homes in a staggered pattern to create the illusion of a smaller building mass. The homes are on a quiet street, with the street front facing south and the backyard north. The subtle windows of the south facade retain the feeling of privacy, whereas the north side has large windows that open onto views of the back yard.

The pitched roofs, solid CLT frame and larch cladding are in harmony with the natural design language typical of the area’s building stock. CLT was used as the frame material for walls, intermediate floors, balconies and canopies. The solid panel surface is visible inside the homes as the walls have no insulation materials or structural layers other than the bare wood. This makes the structure healthy and durable. All window and door openings were machined at the element factory, which made on-site installation quick. The large windows embedded in the frame give the impression of a seamless transition between the interior and the yard.

Extensive excavation and earth moving work was needed on the slopes to build the necessary parking spaces for the three homes. On the other hand, the work made it possible to use the ground floor as a living space instead of a mere basement. The Base Street Trio heating system uses a geothermal heat pump, which is an environmentally friendly and cost efficient choice.