Building a greenhouse, pt. 3

The foundations for the actual greenhouse are now ready, I think. The last steps in this phase included e.g.: using fine gravel and sand (“kivituhka”) to create a top layer that was at right angle and height to serve as the basis for concrete tiles that form the final top layer, supporting the steel plinth. My old heavy wooden ram (“juntta”) was again in use, manually banged down to compress the earth layers. (My academic hand muscles are not perhaps best suited for this kind of work, btw, I noticed the following day…) Before installation of the greenhouse plinth (the steel base), there was one important extra item to take care for, however. The greenhouse was being constructed near – almost underneath – a large old birch, which had already started to rot and drop branches. It was now the very last moment to say goodbye to her (cutting down a large tree later, with delicate glass house underneath, would had been much harder, or impossible). We hired a couple of professinal loggers come and cut the tree into pieces, and there was much work left also to us in sorting out branches (some the size and thickness of regular trees), twigs and leaves. After a full day of that lumberjack work, there was finally time to cast the concrete (oh yes, and a mixture of sand and mortar was brushed into gaps between tiles and dampened to fill them, as a final touch), but before that, the last round of measurements and fine-tuning was done to adjust and fix the steel plinth into the right positions. We had not managed to get all plastic pipes into same exact depth, and a Dremel tool was used to cut few millimeters away from the top of three of the protruding cast pipes. Bubble level was also much in use, and I also applied a couple of spanners to open all the corners of steel plinth, apply small wooden wedges underneath the plinth in a couple of places, and then fix them again, hopefully sealing everything into correct width and length measurements, while also keeping the entire construction at even level, using the bubble level tool. Then it was time to mix some concrete – a small power tool was used, but mostly manual blending (we did not have a proper concrete mixer). It was getting really dark at this point, but finally all the pipes were filled to the brim with concrete (there was beautiful full moon rising, I noticed, and the fireworks from Tampere Venetian Festivals were making popping noices somewhere far away). But: while the doing the control measurements we saw that while the X and Y directions were correct, the steel pinth was not direct – the thin steel bars were tilted (in Z, upwards direction)! It was pretty hard to solve the problem at this point, in dark and middle of the night. But the trick that did it was to loosen again all the nuts and bolts in the corners, move away the concrete tiles that we had used to support and fix the plinth into the right position, as some of them pressed the inner edges of the steel bars inwards so that all of them became tilted. Fixing all that required some fast action, as concrete was already slowly solidifying while all this was going on. While we managed to do all that, there was one measurement that I forgot to take. In the morning, I wanted to kick myself: the front part of Juliana’s steel plinth consists of three separate elements, and I had forgot to check that they were fixed so that the width of plinth in front was the same as the width of plinth at the back (there was room for adjusting the bolts in their elongated holes). We had carefully measured that the diagonals from corner to corner were identical, but forgot to measure that width of back and front were identical. And now all six steel pegs were fixed deep into concrete (with their tips bended, to prevent them from slipping ever out of concrete). Luckily, there was only c. 2 millimeter error between front and back, so the situation was finally not so bad. Hopefully the actual Juliana greenhouse construction has some adjustment room when the aluminium and glass parts will build and fixed on top of the steel plinth.

At this point, we could almost take a little break. But there was still some chainsaw work to do and log piles to build, before thunderstorms arrived to Tampere in the Sunday afternoon. So, maybe a bit later.