Tervajärvi forest chapel

A small wood chapel is now tucked away in the forest of the Tervajärvi campground. Built on a small budget, this project really shows off wood construction and a volunteer spirit at their best.

A small wood chapel has been built on the grounds of the Tervajärvi campground. The Metsäkappeli (Forest Chapel) will mainly serve as the camp church for confirmation camps and as a venue for small weddings or christenings.

The chapel was almost entirely assembled by volunteers. Professionals were entrusted with the more demanding individual phases, with all the glulam parts, for example, coming prefabricated from a factory. The volunteer team’s commitment to the project and the close cooperation between the wood component supplier and the chief designer made it possible to explore different design solutions and try them out on site.

The design premise for the glulam beam structure had two priorities: it should be visually striking, with a connection to the surrounding forest and lake and to the building’s ecclesiastical purpose, and each part should play a role in the structure. In the final design, the beams curve along the length of the roof, acting as their own diagonal stiffening structure. The glulam beam is formed of four 15 mm lamellas with a total cross-section of 60 x 240 mm. The wood is Finnish spruce.

As the interior is relatively small, there was a need to avoid transverse structures. This meant that the corner joints needed to have sufficient rotational stiffness. The wooden parts were manufactured industrially without having to sacrifice the precision and finish of the end result. To ensure the desired quality, a life size practice model was created for the corner joint. It took four separate attempts to find the correct shape for the arcs. The time and dedication were well spent, since all parties are very pleased with the outcome.

The visual part of the corner joints is a surface lamella that continues along the length of the roof. The structural part is inside the joint: a horizontal section that leads vertical loads downwards. The rotational stiffness of the joints was achieved by placing the screws in a circumferential pattern. The screw holes are plugged. The machining of the wood parts and the connections of the corner joints were done at the factory. The parts were then delivered to the construction site as pre-assemblies of two roof arches connected to a vertical wall section. The volunteers then assembled these parts on site. The vertical sections are glued with PU glue to threaded rods that stick out from the sole plate and fit into placeholders in the wood sections. This way, no fasteners are visible indoors.

The chapel roof is constructed from grooved planks made of Siberian larch. The roof and exterior surfaces have been treated with tar that has been tinted with charcoal black. The roof planks have only been attached in the middle to prevent the wood from cracking as it expands and shrinks with fluctuating moisture levels. Because wood gradually forms a convex curve on its heartwood side, the planks have been laid out with the heartwood upwards to retain water tightness over time. The underlay is breathable.

The forest chapel is mainly used in summer and is not meant to be heated during winter time. Underfloor heating provides comfort in the chilly early and late summer. The wall and roof structure are permeable to water vapour and the building is ventilated along the entire roof top ridge.

The chapel’s movable furniture, including the brass components, was custom designed for the building and made to order by Puusepänliike Hannes Oy. The material is larch. The joints and other details of the furniture were developed in collaboration with the carpenter.