Construction Execution

This part is about providing a better understanding of what a typical construction process looks like and what the expected or at least minimal standard is. Poor and potentially dangerous details like in this photo can be found everywhere, and if one understands at least a little about how the construction process should look, it may help to ask the right questions and avoid such situations. Again, it is a matter of expectations. A demanding project like this example from Ghana certainly requires a much greater effort, when the construction process begins.

For this, a suitable team is needed – starting with the architects who handle the planning, down to the construction companies, who are willing to collaborate and try new construction methods. And then there is the so-called usual way of building, something that is quite familiar to every local and if one chooses this direction, certainly few questions will be asked. Both options can be good and lead to successful projects. What is important is to be clear about this from the start and to adjust the process accordingly.

Regardless of the type of project and the level of execution, one should always adhere to some technical minimum standards and seek external and independent support for construction supervision. Sometimes this can mean that enough nails are used to connect the wooden elements, that one takes better care of the concrete elements of the buildings or that basic standards, like the lighting protection for public buildings, are implemented.

There are mainly two things that one should consider when preparing a construction project, before looking for a contractor or a team that will carry out the construction. For both, one must spend a lot of time behind the computer screen. The first and most important point is a clear idea of how the construction is to be executed and thus a good specification, that is “Bill of Quantities”. The more detailed, the better.

It initially serves to account for a contractor’s failure based on various offers and later facilitates the tracking of building regulations. The second point is a detailed construction documentation. This naturally makes the entire process much more transparent and anticipates many of the possible challenges that will arise on the construction site. Here is an example of how such documentation should ideally look. It can of course also be presented in a less detailed manner.

The reality is that it is often very difficult to find someone who can create such detailed documentation, considering that this is often done for free or for symbolic amounts and should happen within a very limited timeframe. Here at We-Building, we have conducted such detailed project planning for some projects that we realized together with our partners, and we are well aware of how much work that is, even if one has experience from previous projects. When it comes to different construction companies, it is always a matter of chance.

And until the project is completed, it is hard to know how the collaboration will go. If one can get recommendations from reliable companies, that is always good. One should just be careful with all those, who make very cheap offers or with those, who ask very few additional questions and constantly say that one does not have to worry, because they have a lot of experience.

As soon as alternative construction methods or new elements such as pivot doors or roof openings are introduced, it would be quite possible that the contractors would simply do it their own way doing it without regard to the plans or the specifications. The explanation goes something like this. ” Yes, but that’s not how it’s done, we know, how it needs to be done, no worries.” When the construction work begins, the best security mechanism is a very good construction supervision.

It should primarily be conducted by a local engineer who is as independent from construction companies as possible. Furthermore, the constant or occasional presence of volunteers with engineering background would be beneficial. Background is advantageous. They can then monitor and document the construction work and respond immediately, if changes are necessary or if there are problems on site. The absolute minimum would be for someone, even one of the youths living nearby, to take as many photos as possible every few days and send them via WhatsApp.

This way, one is always informed about the construction progress and there are archive photos for future references. A real-time overview can prevent a situation like this, where the contractor accidentally rotated rotated the building 90 degrees. Through an immediate response, such big mistake could be avoided. One or two weeks later, damage control would have been necessary, because it would have been very expensive to tear everything down.

Other examples include adjusting the project during ongoing operations and making design changes based on feedback from the construction site, respond to inquiries from the construction site and assist in the search for solutions to various everyday problems as well as pointing out obvious mistakes, that can be seen in the photos. All of these photos are not only needed, to track the construction work, but they are also essential for the creation of various reports that must be presented to the project stakeholders during the construction work. They are crucial.

There are actually never too many photos or construction reports. Another point, that is very important during the construction phase, is very detailed and regular bookkeeping, as well as the careful collection of all original receipts. Since things always get lost, one should always ensure that at least photos of each invoice are archived, as soon as they arrive. After construction, it’s time for all final reports and evaluations.

One should not forget that it is common to monitor and check buildings for several months or up to a year – depending on the contract – to see if there are any minor or major defects, that need to be fixed. It is also advisable, to pay 5-10% of the total contract amount only after this period. It can sometimes be difficult to coordinate with the various contractual funding obligations, but it is worth trying. We will now go through a typical construction process for a simple ground floor building in concrete frame construction, which is a fairly basic way of building.

This way, one can get a better idea of what the construction site actually looks like and what to expect. Everything begins with staking out and marking the corners of the building on the ground to position the building. The more complicated the floor plan is, the more attention should be devoted to this task. Ideally, this should be done by the construction company, but even then, it is advisable to check a little. There are too many examples of this, where buildings were constructed a few meters away from the planned location.

This is something that cannot be corrected later. and even professional surveys can easily make mistakes, so an additional check is always welcome. As soon as the building is positioned – with the utmost precision – the engineer of the construction company takes over the work, hopefully with the right measuring equipment and ensures that everything is orthogonal and exactly matches the dimensions in the drawings. Then excavation begins and the foundations are dug. Since the earth will serve as formwork, everything must correspond to the actual dimensions of the various foundations and be executed very precisely.

This is where the steel bending begins. All the steel is usually bent at the beginning of the construction work and a specialist, the so-called steel bender, takes over the work. He usually looks for a place in the shade with enough space and sets up his table and the necessary equipment. The work is carried out independently of the actual events on the construction site, but of course as close as possible.

Over the course of several days, all the steel that is to be used for the reinforced concrete parts of the building is prepared. This essentially involves foundations, supports, and beams. For this, the plans in which the individual parts are defined must be present on the construction site. The reinforcement steel is then placed with the utmost precision into the excavated foundation trenches. The height, angles, and distances are constantly monitored while the steel parts are secured, so that they do not move. This is also an irreversible process, where errors are difficult to correct. This is why everything is checked multiple times.

Once all the reinforcement steel is positioned, the production of the concrete begins. Sand and gravel as well as numerous bags of cement are already on the construction site, ready to be used. There should always be a constant water source available, as a lot of water is needed, especially on remote construction sites without a pre-exisisting water source, it can often pose a problem. Now the production and pouring of the concrete can begin. This is a very hectic and dirty part of the construction project, which requires many workers, who all perform different tasks simultaneously. That’s how it looks.

First, the column foundations and the foundation strips are poured, with the top layer kept as level as possible. The reinforcement steel for the columns is connected to the steel of the foundations and extends upward. When building on sloped terrain, you can also see how the foundations are laid in a terraced manner, to adapt to the slope. In order to begin pouring the columns, a formwork must be created.

It is usually made of wood, but in this example, we show a better alternative, where the formwork is made with a modular plastic mould. Such a thing is not always available, but when it is, it is a much more sustainable solution, as the plastic elements can be reused multiple times. The panels are connected to each other around the steel rods. In this case, a bit more digging was needed, to make room for the panels.

This process is repeated for each support with a high degree of precision. Once all the foundations for the supports are prepared, the pouring of the concrete can begin. Since the supports are quite thin, in this case 20 x 20 cm, it is very important that the concrete completely fills the entire space within the formwork. This can be done manually, as shown in the video, by simply pushing with a rod and trying to ensure that the stones in the concrete mix do not form air pockets.

Ideally, a suitable device is used, which vibrates the concrete and performs better. The machine is usually powered by diesel. After a few days, the formwork is removed and the supports become visible. This first part goes up to the height of the future ceiling. When connecting concrete elements, the steel reinforcement must always have an overlap and is therefore always left to protrude a bit, so that they can be connected when the next part of the support is poured. The foundation wall is then made of cement blocks, which are positioned between the supports, until the entire perimeter is enclosed.

If necessary, these walls can also be partially reinforced with steel. This was the case in the following example, as the ground pressure on this wall was quite large. The cement or sand concrete blocks, which are usually used, are made on-site and can be easily cut and adjusted to fill any part of the wall. Here are some alternative ways how the same procedure can be completed.

For foundations, old metal barrels can be used as formwork, which then remain in the ground. An alternative to using concrete for strip foundations is to use large stone pieces as a base, then cover them with a thin layer of concrete, to create a horizontal surface. This way, less cement is used. But this is only possible in areas where there is a lot of natural stone available. And here is the classic way how the concrete columns are made. Basically, the process is reversed.

First, the foundation walls are built, between which the reinforcement steel is placed. After that, wood is used to close the two remaining sides and create the space into which the concrete will be poured. Depending on the availability and and safety of a specific construction site, various techniques can also be combined together. Once the columns and walls are completed, the earth is filled back in, to fill the entire space. It must be compacted very well.

Depending on the depth, this is usually done in several layers, with each layer being compacted, before more earth is added. The process takes a bit longer, not only because it is manual labor, but also because the soil needs some time, to settle on its own. Rainfall helps with this. It can also be done by hand, as shown in these photos, but of course, it goes much faster and better, if you have suitable machines, like this soil compactor.

Once the base is prepared, the new reinforcement cage is connected to the one that hangs out from the base columns, and the formwork process begins again. In this case, the entire length of the column was poured at the same time. It always requires a lot of out-of-the-box thinking, to ensure that everything stands and is almost connected. The production of such a tall column element was possible because the vibrating technique for concrete compaction could be used.

The concrete is poured in several layers and then each layer is first vibrated before the next one is added. It can also be worked in stages, by gradually raising the formwork, when a segment is finished. This is what the same process looks like, when the classic wooden formwork is used. The finished columns, after the formwork has been removed. And here you can see what happens, when the concrete is not properly vibrated and air pockets form. Such errors must be promptly remedied, so that the steel in the columns remains protected from corrosion.

Visually, not much can be done, and these errors will always remain visible, as long as the columns are not plastered. The last part of the concrete skeleton is the beams, that go on top. The formwork is currently being prepared, held from below by various temporary wooden supports and closed on both sides. Unfortunately, there is no alternative to wooden formwork for the horizontal concrete elements. Since in this case the outer surface of the concrete should remain visible, in order to avoid plastering, film plywood was used to achieve a smooth surface.

The steel in the beams is connected to the steel in the columns, both sides of the beam are closed and then the concrete is poured. For the beams, the formwork holds the beams from below, therefore must remain for at least seven days, before it can be removed. The main shape of the building is now complete.

As with the foundation, the upper supports and walls can also be constructed in a different way. The walls made of cement blocks can be built first and serve as formwork for the supports from the sides or for the beams from below. The same applies to the walls made of fired bricks. First the bricks, then the concrete. This construction method is only possible with elements that do not absorb water from the concrete. Alternative wall construction methods with clay or wood can only be carried out after the concrete has hardened.

Another option is timber frame construction, in areas where quality wood is available at reasonable prices. This is a very fast construction method, where all supports and beams, as well as all stabilizing elements are made of wood. The wooden structure is conneceted to the foundation, with steel shoes. Once the load-bearing skeleton system is complete, the roof construction can continue as with the other methods. A very similar method can be carried out with steel frames, but then the roof construction will continue in the same way and everything will be made of metal.

The final concrete work can now begin, namely pouring the floor slab. The underside is prepared and sand is spread on the ground. All sides are closed with a wooden formwork, which is connected to the foundation walls. Underneath, a layer of PVC is laid. This material is used because more suitable sealing systems are generally not affordable. It is carefully spread out, to cover the entire area, but also to allow various steel parts or installations to pass through.

In most projects, that are carried out in warmer climates, the temperature never drops below zero and most moisture from the ground that penetrates into the structural elements, evaporates quickly. A compromise solution like a simple plastic layer that is not even properly sealed, can actually help to some extent. Now the pouring of the concrete can begin. In this case, it is about a 15 cm thick slab without reinforcement. This thickness is a minimum, to prevent cracks from forming during later use.

These floor slabs are not load-bearing elements, but serve as a layer, that covers the subsoil and forms the final floor covering. For a room of 50 m², about 7.5 m³ of concrete is poured, which is much more than for all other elements that have been produced so far. This takes a lot of time and larger floor slabs are usually produced in sections over a period of two to three days. Spraying the concrete surfaces with water is a common measure to prevent premature drying.

The concrete must remain constantly wet in the first seven days, which is particularly challenging in very warm climates. That is why it is watered daily, with great care and attention. Another helpful option is to protect the top layer with a plastic film, to reduce evaporation and maintain moisture. Alternatively, the slabs can also be reinforced, with a steel mesh as reinforcement, which allows for thinner slabs of about 10 cm and actually is a better option, since significantly less concrete is needed. The price for both options – with or without reinforcement steel – is similar.

And this is what the finished surface looks like. It can be left as the final floor covering or used as a base for tiles. When the slab is finished and the skeletal system is in place, any type of wall can be inserted in between. Here you can see various examples of compressed, stabilized earth blocks. These walls are non-load bearing, but they must be connected to the main structure. More examples of simple, sun-dried earth blocks or factory-made bricks.

One of the most important workers on any construction site is the carpenter foreman. In addition to the components made of wood, such as the roof structure, this person is also responsible for the production of various other equipment used on the construction site. For example, the formwork, wooden supports, various tools, and so on. He is present from the first to the last day of construction and for this reason has a fixed place on the construction site and a work table in a shady spot.

The construction of the roof begins with the use of wooden beams on the ground. The long wooden elements are made from several parts, connected with nails. After that, the elements are lifted onto the concrete beams and connected to each other. Until the entire structure is erected, they are temporarily held in position with various means. When building on concrete elements, a wooden wall panel is usually attached to the beam to facilitate the connection of the wooden elements to each other.

After the load-bearing elements are installed, rafters and battens are connected, to create a complete structure and a base on which the roof sheets can then be installed. Roofs can be built in many different ways and some of them are much simpler, but – as can be seen in this photo – the standard can be very low, without proper stabilization with wooden elements that are too weak. Usually, it doesn’t disturb anything and everything somehow holds together, but in the event of a severe natural disaster, be it a storm or an earthquake, most of these roof structures would likely be damaged.

Optionally, sound insulation against rain can be applied. Most commonly, filled mosquito nets are used for this, but other options are also possible. The nets are filled with wood shavings and attached to the wooden structure. This is the faster method. Another option is filling from below, which takes more time, but provides better protection from rain during the construction process. The choice of method depends on the season. And in the rainy season, the metal roof should be installed first.

It is important that this sound-dampening layer is then placed between the sheets and a ceiling. In this way, a composite is created, like a sandwich, to dampen the sound. Here it is done with plywood, which will later be painted white. And in this case with raffia branches, which are nailed together. A variant with bamboo is also possible. For the roof covering, sheets are almost always used. They are delivered in large panels, that are then screwed into the wooden elements of the roof.

If the roof shape is simple, like in this shed roof, then the process goes very quickly and involves very little cutting. With more complicated roof shapes, it takes longer and many sheets need to be cut, resulting in many leftover pieces because in the quantity calculation must be taken into account.

The final result looks like this. It looks very precise, until you get a little closer and see many strange connections. That is normal and to be expected. And it is important to know how these panels are usually cut. There are usually no proper electric tools for this, but often just simple sheet metal scissors. The corrugated sheets are connected with special screws. Here are some more photos of various finished roofs.

As you can see, it is a very complex process, even with simple buildings like in all these examples. It is very technical and good preparation is helpful, but one should always keep in mind, that behind it all are always individual people with different skills and experiences. The final result always depends on how good the team behind it is and not on how it should be in theory.