Janne and I talked in more detail about the process of making the foundations. Once we get the permit go-ahead, Janne will rent a drill and order the concrete, along with reinforcing steel bars and a bunch of paper tubes.
For each foundation point, he'll drill down at least 20cm, (maybe more depending on the quality of the rock), and slide in a few steel rods. The paper tube goes over the rods and is filled in with the concrete to make a cylindrical post. The tubes are supported by lumber to keep them straight during pouring and curing. The plan for our main house (shown above) calls for 10 foundation points.
Janne has a laser mechanism to ensure the tops of all the foundations are level. Because the rock is uneven, each of the foundation tubes will be different heights. By the front door, they'll be 20 or 30 cm, and in the back, facing Claes' house, they'll be much higher, well over a meter. That will be handy to for us to fit the water tanks under the house.
About hundred 20 kilo bags of concrete will be needed. I plan to take a few days off when Janne's ready so I can provide the manual labor to haul everything up from the dock, and to help him with the foundations as much as I can.