With the first-floor ring beam now cast, the next stage is the placing of the floor planks.

As before, K.Pot checked the ring beam was solid and ready, then re-checked the spans between the beams. This was to ensure the right length planks were purchased.

As mentioned before, it is not only the length calculation to specify the planks. As the length increases, it is important to make sure the plank can carry the load – longer planks require a greater density of rebar inside, and may even become thicker as a result of the increase in steel

With the required information gathered, he placed the order with the plank supplier. A few days later, the flatbed truck turned up, loaded with planks. The planks had been loaded in a systematic way so that they could be unloaded in a sequence of placing. This was also worked out by the builder beforehand, to make the plank placement a lot easier.

The truck came with a crane attachment and further, a lifting frame so that multiple planks could be raised up in one lift. This speeded up the whole placement process.

As each set of planks was raised, the building crew crow-bar’ed them into final position, making sure they were butted right up together. The first floor soon took on a solid appearance as the planks were placed, but it was important to remember… those planks were not yet secured, they were only sitting in position by the weight of the plank itself and could still move if any force was applied to them sideways and they could fall. With regards to this, while the plank placement was taking place, no one was allowed on the ground floor under the planks at all…safety first. The checking underneath came after all the planks were placed.

During the plank placement, it was necessary to make small cut-outs on some plank corners to fit around the locations of the first-floor columns

Finally, all planks were in place and the first floor was ready for the next stage – re-enforcing mesh placement and concreting, but before that, another separate stage had to be completed – the casting of the first floor columns.

Concreting

Yes! It’s concrete time, again…

With the steel and shuttering all in place and checked, K.Pot ordered the delivery of sufficient concrete to pour the entire ring beam in one go. It would have been too much to try and mix this quantity on-site, so mixer trucks were organised to deliver the wet concrete to the project.

In the collection of work vehicles, the build team had access to a crane and concrete skip, so all the mixer truck had to do was reverse up onto the site and fill the skip. The crane would then lift the concrete batch up to the ring beam location, and the process was repeated until the mixer truck was empty.

Once the trucks started arriving it was ‘all hands to the task’’ as the skip was repeatedly lifted to the ring beam, and unloaded into the shutter. Care had to be taken to make sure the shutter was totally full of concrete, but not over full and spilling out onto the floor below.

It was also important to make sure the concrete had ‘flowed’ around the steel rebar, so that there were no air-pockets inside the beam. Air pockets would create a weakness in the beam, which could lead to floor failure if the beam collapsed. To prevent this, the foreman allocated one worker to be in charge of the concrete vibrator to help the concrete completely enclose all the rebar.

While the concrete pour was taking place, the foremen and one other worker were constantly checking the shuttering to look for leaks or possible failure potential. We think of concrete as a hard mass of rock-like substance, but in its wet-state it has hydraulic properties, especially with regards to pressure. Even in a shallow shutter, the mass of wet concrete is constantly pushing out, trying to escape the shutter, in a way that hardened concrete would not. The deeper the shutter the higher the pressure as you go down. It is less relevant in beam shuttering but much more so in column shuttering.

Once the bulk of the shutter pour had taken place, some finishing work on the shutter had to be carried out by hand. A smaller quantity of wet concrete was placed in a large bowl and then bucketed to where there was small dips in the surface, to bring it up to level.

At the same time as the beam was poured, the team also poured the floors for the bathrooms, which were lower than the actual beams, so that they were completed before the main floor slab (the next task) was planked and poured..