Day 8: Moulds Removed, Concrete Drying

Today not much happened at the site. In the morning, the moulds were removed, and the walls were covered by large tarps. Also the heating system for the concrete was removed. In the early afternoon, I met the site supervisor at Our House, and we discussed the work so far. First, however, we used a very fancy thermometer to measure the surface temperature of the concrete foundations. It turned out that they were frozen in some places (which is bad), and clearly above freezing in other places (which is good). Later in the evening I returned and with the help of my colleague Juha, we covered all the remaining walls. Now the chemical reaction in the concrete is the only source of heat. Let's hope that is enough. The countdown is definitely running: the house will come in a week's time!

The instrument, when pushing a button, projects a crosshair with a laser onto the surface to be measured, and then it does the measurement instantly using the infrared radiation from that surface. In the photo above I am checking out constantly cold floors in our current flat with the instrument. The minimum and maximum temperatures are the ones observed during the same session, and in this case I had pointed at the cold window, and at a halogen spot light. The device is rated to measure temperatures between –35°C and +950°C with an error of less than a degree. This comes at a price, the IR thermometer costs roughly a thousand euros, but fortunately we were able to borrow this one for free.

Since no new photos were taken today, here's an old one from 18th December, when the company, which owns the local electrical grid, brought the cable to our plot. Since we will be slightly off the main road, Rovakaira needed to place three poles to suspend the cables from, and then continue underground to our plot. From there, we had to bring the cables to the house, which happened on Day 5.

Day 7: Use Oil Pressure, Not Blood Pressure!

After yesterday's concrete delivery, the foundations were left to dry for about 30 hours. Tonight, the team from Pohjois-Suomen Perustuspalvelu returned to check the progress. There was water standing in places on top of the concrete, i.e. the temperature at the surface was just above freezing. Fortunately last night's temperature was rather high for this time of the year, only about -8°C, as shown in the graph of the real-time thermometer of the Sodankylä Geophysical Observatory.

The pump will still be running for another day keeping the base of the foundations warm. Most of the heat for the drying process comes from within the concrete: the chemical reaction inside generates a lot of heat, which leads to a self-drying process, even in winter, if the mass is just large enough – like under our future fire place.

However, last night a lot of snow fell, as seen in the previous photo. All of the snow on the tarp came overnight. It looks quite bad, and I am not looking forward to the prospect of having to shovel it all out, but we shall worry about that on the weekend. The weather forecast is promising: no more snow fall before the delivery of Our House on Thursday, 17th January.

Today, all the moulds were collected, since the foundations are basically hardened already. When the question arose of how to collect them from the far side of the building, one of the team said "Better use oil pressure than blood pressure!" – Of course he was referring to using the hydraulic pumps of the crane instead of carrying all heavy elements to the lorry.

Day 6: Concrete for the Foundations

Today was another race against the clock. The concrete mixers were scheduled to arrive at 10 a.m., but the electrical cable, which was put down yesterday, needed still to be connected to a temporary fuse box. This process was going on when the first concrete mixer/concrete pump lorry arrived. The photo above shows the readily connected fusebox (grey, in background), as well as the heater/pump system to heat the concrete in order to harden properly despite the frost (grey and red, foreground; the red hose runs through all walls).

The team had done a fantastic job until late last night, and certainly again early today, in order to prepare everything ready for the concrete. The photo above shows the space to be filled, including the steel reinforcements and the red heating hose on the bottom. It seems Our House has central heating already!

At some point we had three concrete lorries on the yard. The one on the right stayed all the time, since it was a combination of mixer and concrete pump. The other lorries came and went, and poured their concrete into the first lorry.

Via the hose at the end of the long arm of the pump, the concrete flowed into the moulds rapidly – and problems appeared. It turned out that our contractors didn't do their job properly and flatten the ground enough. This resulted in large gaps under the moulds. While unfortunate in itself, it was then aggravated by the consistency of the concrete, which was delivered with too high water content. This meant that it was very liquid and flowed straight out of the bottom of the moulds in many places. We ended up needing a couple of extra cubic metres of concrete, another delivery, and lost time. We'll have to see what to do about that in the end. The rather atmospheric shot above shows the end of the hose delivering the concrete, and the flash highlights nicely all the steam in the air: the concrete was delivered hot in order to prevent freezing.

The result looks great though, and owes a lot to the highly competent team from Pohjois-Suomen Perustuspalvelu Oy, who prepared and executed the foundation work – they worked very hard indeed and did a fantastic job. The photo above shows the ready product (well, a corner thereof) after the top had been levelled to the exact building height with the help of a laser level as a reference. The laser is just visible in the distance as a red spot.

PS: Click on the photos for enlarged versions.

Day 5: Start of Foundation Work

Today was my first day on the site, and I learnt an important lesson: if you know what you want your contractors to do, don't leave them to do it alone. Quite a few things were not as expected, despite detailed drawing and explanations. Thus the morning was a race to work around the missing bits. Most importantly, the electron inflow promised for Saturday had not been done, and thus a long trench was dug first thing in the morning. Fortunately, we had asked for spare tubing to be inserted in order to feed electricity out of the house for future buildings and lighting etc. These came in handy now, because they proved the only way to get electricity delivered in first place.

A big "Thank You!" goes to the technical staff of Rovakaira Sodankylä, which – for the second time in a few days – changed their plan for the day instantly to respond to my calls for help. Well done! The photo shows them suspending a cable drum from a crane above the trench. They then unrolled the cable from there as much as needed.

The cable was then tied together with a copper grounding wire and pushed through my 50-mm white plastic tube into the area inside the foundations. The white tube on the right is a bit cut off accidentally by the digger – we had to rush, and there was no time for shovels, because the next work team had already arrived.

A lorry from Oulu brought all the bits and pieces to make the moulds for our foundations – and those of an identical house to be built elsewhere in Sodankylä soon after our's. Here one can see the team unload the first pile of wooden walls, which will later form the moulds. Also visible is the FinnFoam, which has been spread out in the areas of the foundation walls. The foundation will be hollow, consisting of a rectangle and a wall longitudinally in the centre for extra support. The thing on the tripod in the distance isn't a camera (not yet!), it's a laser levelling system.

The final photo of today's blog entry is a picture of the van belonging to the other member of the two-person foundation work team, bringing extra equipment, and featuring a 220-V inverter and a microwave oven. More important for us is the machine in the foreground, and the canisters. This is the heating system, which allows for the concrete to dry our fast despite the cold. When the concrete will be poured in, pipes will be embedded in it, through which a special, heated liquid will be pumped. The machine in the picture is a pump and electrical heater combination. By heating the concrete, it will dry out in some 24 to 36 hours.

Fortunately, the temperature was a rather pleasant -10°C all day with a thin cloud cover, but in the evening the sky cleared up and some stars were visible, so it might get cold. Tomorrow early morning, the concrete will arrive.