Janica and Arto built a seaside villa nestled into solid rock with no building experience

Standing on the road that winds through the Pellinki island village of Porvoo, southern Finland, you can only see the ridge of the roof peeking out from behind the rock. The two-story, wood-clad house is tightly snuggled into the embrace of the cliff.

Inside the house, which is called Villa Berg (Swedish for “Villa Rock”), the reason for its custom fit becomes apparent. The cliff has been excavated on three sides so that the rear wall of the building is entirely made of rock, as are the side walls for the most part. What comes to mind immediately is the Temppeliaukio Church in Helsinki, where solid rock similarly serves the purpose of walls.

The exposed rock has been left largely untouched. Drill holes from the blasting are visible, and a few drill rods that became lodged in the rock have been left protruding as mementos. You see, the bedrock in Pellinki is exceptionally hard, which impacted the construction significantly—a topic we’ll delve into shortly.

Here’s how the house looked during the renovation:

The project was initiated by Pellinki fisherman, restaurateur, and force of nature Martin Tillman over ten years ago. The fisherman’s farm of just under half a hectare already had a couple of buildings.

Construction started off fairly smoothly. The concrete block walls went up, and the roof structures were completed to protect the building from the weather. Then work halted. It turned out that the building permit process had not entirely adhered to regulations.

The construction site remained as it was for ten years. Swallows built nests under the shelter of the felted roof.

Janica Ström and Arto Soininen, an entrepreneurial couple from Porvoo, heard about the sale of this property a few years ago. The house, called Pellinge Marina back then and built halfway into the rock, made many interested buyers think twice. Arto, however, has a lot of experience in excavation and saw the potential of the skeletal building. It was a deal.

“When we bought it, we didn’t know if the excavated building could even remain here or if we would have to demolish it,” Janica recalls.

“We had, of course, contacted the municipal authorities in advance, but no one could tell us anything.”

Janica and Arto recruited an experienced leader for the project, architectural engineer Kalle Oikari.

“We are so lucky that Kalle agreed because without him, this house would not have been completed,” Janica says.

Even before the sale, Porvoo’s building control services had implied that they considered completing the construction a very good idea. Of course, a building permit would be needed, probably a deviation permit too, but it would all work out.

But as it happens, it wasn’t that easy.

“The road that passes by our house is marked a scenically valuable road route. That’s why all properties along the road are under special scrutiny,” the architectural engineer explains.

The plot didn’t actually have any building rights. Everything had to be planned first and then presented to the City of Porvoo.

The permit process was made especially—sometimes downright infuriatingly—laborious by the fact that, besides the building control services, many other parties wanted to have a say in the project due to the road being a significant scenic route.

“There was Urban Planning, The Finnish Heritage Agency, the Centre for Economic Development, Transport and the Environment, other city committees, health authorities, fire authorities... And every time we proposed something, someone had a different opinion. Luckily, Kalle had the patience to explain,” Janica sighs.

“We put the most effort into getting Urban Planning to grant us the special permit. After that, getting the building permit was much easier,” Kalle says.

After many exhausting stages, the permits were sorted out. However, the property is designated for service business according to the building plan, so they couldn’t build a house for living. This suited Janica and Arto’s plans well; from the beginning, their intention was to build a waterfront restaurant, accommodation facilities, dozens of boat berths—and a cliff villa for company meetings and team-building activities.

Kalle Oikari got to work. The first major challenge to solve was redirecting water flows away from the house.

“We made the waterproofing and slopes on the exterior of the building with concrete filling, but there was a risk that water could force its way in through the rock cracks during a flood.”

In the aforementioned Temppeliaukio Church, this problem has never been completely solved.

Sealing the rock required special expertise. They had that in-house, and Arto took on this work. Potential leak points were high-pressure injected. Holes were drilled into the rock, and concrete-based filler was injected into the holes.

According to Arto, Pellinki’s rock is the hardest stone he has ever worked with. Correspondingly, hard rock has fewer cracks than usual and thus less need for injection.

When you have bare, chilly rock as walls on three sides, keeping the house warm must be incredibly expensive, or is it?

The architectural engineer shakes his head. A meter of dry rock is equivalent to a well-insulated exterior wall.

“The most critical point is the junction between the wall and the rock, where the rock thickness is at its shortest, about 40 centimeters. If the rock is very cold at the base of the wall, the moisture in the indoor air can condense on it. This issue was resolved with enhanced ventilation.”

The mechanical ventilation has a heat recovery system. The main heating is provided by a geothermal heat pump. Martin Tillman had wisely built the frame from 400-millimeter insulated lightweight aggregate blocks, which sufficed as is.

Kalle designed a half-meter layer of cellulose insulation for the ceiling, typical of modern construction. The base floor was completely redone. The old slab was chiseled away, and the foundations were excavated and moved down by almost half a meter. Gravel and frost insulation were added. Pipes were installed for geothermal heating, water supply, sewage, electricity, data cables, and radon ventilation. Then came the underfloor heating pipes, new cast, and finishing with ceramic tiles.

Municipal infrastructure is a whole different world in the archipelago. The nearest water and sewage connection would have been almost a kilometer away. The couple would have had to excavate a trench for the pipes along the roadside—a massive undertaking.

“We got the opportunity to run the pipes through the seabed, which is a much more sensible solution,” Janica says.

Sewage now flows via gravity sewer to a pumping station on the shore, from where it’s pushed to the municipal pressure sewer 700 meters away. Water supply pipes carry clean water the same distance in the opposite direction.

The architectural engineer couldn’t really influence the appearance of the house. The frame was already up, and they had to proceed accordingly. The upstairs windows were enlarged, and new windows were made in the downstairs bedrooms.

“I turned things over in my mind. How does it feel when I walk here and turn there? Is this a smart solution that works?”

Thanks to all these carefully considered solutions, the owners of Villa Berg can expect a long and successful future.

Villa Berg’s floor plan: