Worlds most Artistic Architecture

The Basket Building in USA

What started out as a dream by Dave Longaberger, Founder of The Longaberger Company, has been built Home Office into a giant basket to house the entire corporate offices of the company. Dave believed the idea was one of his best and would draw attention to the company, while simultaneously helping to build our brand. However, when he started spreading the idea of building a Home Office that was really a basket, he found that most people just thought that Dave was making a joke as Dave was a notorious practical joker. Not only did the bankers, architects and construction companies not take Dave seriously, neither did many of the employees who worked for The Longaberger Company, but Dave persevered. The dream was achieved on December 17, 1997 when the Home Office that is designed to resemble a basket finally opened for business. 

Stages in a construction project

The stages in a construction project can broadly be divided into the following. 

1. Preliminary or reconnaissance survey
This is a general visit to the site and is performed before setting out. This can only be compared to the due diligence background check that courting couples perform before tying the nuptials. At this stage one is able to identify the challenges that one may encounter during setting out & construction. This may include setting out in a swampy area or on a slopping site. One is able to identify the appropriate measuring and marking out equipment that will be needed during setting out. This is just like the young man who sends out ‘spies’ to find out the type of family his bride to be belongs and prepare himself by having enough presence of mind not to bolt during lengthy discussions.

2. Setting out
This is the science of interpreting architectural drawings and conveying the results on the ground ready for construction. This is discussed in greater depth in the preceding article titled ‘Setting out your building’. Usually the results & observations generated from the preliminary survey will go a long way in ensuring that the setting out exercise is conducted smoothly.

3. Site Clearance
This is the physical removal of all objects and obstacles that fall within the proposed building location. This includes trees and bushes, rocks and boulders or temporary buildings.

4. Substructure works
These are all the works that are performed while putting up the foundation of a building. They include excavation work, casting of foundation footings, construction of foundation walls and casting of ground floor slab. Successful substructure works heavily depend on accurate setting out. They must also be performed under the direction of qualified personnel because solid and enduring buildings entirely depend on solid foundations.

After the above 4 steps have been conducted successfully, you are one step closer to having your dream house.

Until next time, build safe.

Fundi Mjanja.

Setting out your building

Setting out a building is simply the art or science of interpreting architectural drawings and conveying the results on the ground. Simply put setting out is transferring the drawing from the paper to the actual site in order to facilitate construction and is usually amongst the first activities that are performed on site. It is where for example one is able to find out if the building will fit into the plot & exactly how many trees & bushes need to be chopped off in order to accommodate that new house.






The requirements for setting out regardless of the complexity of the structure broadly fall into the following 3 categories.


• Drawings
• Measuring & marking equipment
• Competent personnel


1. Drawings
Whether you have been commissioned to do the setting out of Kenya’s first nuclear station on Migingo Island or to do a humble ten by ten chicken pen in your own backyard, the common denominator is that you must have a drawing. If by chance you happen to find yourself in a frantic activity involving measuring out a building using strides & footsteps with no drawings then, the information contained in this article is not meant for you. Setting out specifically involves transferring the information contained in a drawing to the ground therefore you must have a quality drawing to begin with.



2. Measuring & marking equipment

Just as pen, paper & perhaps a dictionary is required to transfer ones thoughts to paper, equipment is needed to transfer your dream home from the architects blue print to terra firma. Measuring equipment may include tape measures, compass, levels and manila strings. Marking equipment may include pegs, chalk or paint. Equipment required entirely depends on the type of structure and the type of terrain. This brings me to the third and by far the most important requirement for setting out a building; competent personnel.


3. Competent Personnel
Having a qualified professional to do your setting out will ensure that guesswork is eliminated from this very important exercise. It will also save you, the client the hustle of having to buy expensive measuring equipment that might only be used once. Proper setting out also allows the client to visualize the exact position of the building in relation to other objects in the site area and avert encroachment to neighbors property or damage to utility lines like sewerage and water lines. Qualified personnel can be found in our website from the following link:
http://fundimjanja.com/index.php?page_id=7&pcat=17 

Building on a firm Foundation

Building on a firm foundation

What does the cervical, thoracic and lumbar vertebrae all found in human anatomy have in common with strip, raft and pad foundations found in building construction? The cervical, thoracic and lumbar vertebrae all form part of vertebral column or the back bone of a human and they are responsible for most if not all of our movements. They are also responsible for the stable functioning of other body functions by providing a stable foundation on which our limbs can find support. My limited physiological knowledge also tells me that damage to the back bone is one of the most detrimental injuries to a human. So how does these information tie in with the foundation of a house? The foundation or the sub structure holds everything together in a house. From the doors to the windows, from the sockets to the taps, from the paint to the tiles; no single component of a house is as important as a good foundation. Just like the spine in human anatomy, the foundation is what holds everything else together. It is therefore imperative that adequate time and resources are allocated in the construction of a house to ensure that it has a solid foundation.

A good foundation is one that is able to safely transfer all the dead and imposed loads from a structure to the ground beneath it. The dead loads refer to the foundation’s own weight, the weight of walls, doors, windows, tiles and roof. Dead loads are the vertical forces that are perpetually imposed on the ground below and hardly ever change. Imposed loads on the other hand are loads that change with time, this can be forces imposed on the roof due to rain and wind, forces on the floor slab imposed by occupants and furniture arrangements and the like. The foundation therefore is supposed to transfer all such loadings from the building to firm strata below.

And where do we start in ensuring a good foundation for a building? Most seemingly complex endeavours normally have very simple and straight forward answers and building a strong foundation is no exception.

As I have mentioned above “a good foundation is one that is able to safely transfer all the dead and imposed loads from a structure to the ground beneath it.” Therefore since ALL the loads of the structure will eventually be transmitted to ground below the structure it is important to conduct a proper ground investigation. For large complex structures like shopping malls, large school and hospital blocks, communication towers and the like; this will involve engaging a geologist who will prepare a geotechnical report based on actual site investigations. This is because such structures transmit complex loadings and forces on their foundations and exact site conditions must be verified to ensure safety. However, for your humble 3 bedroom house, ground investigation might just involve rolling up your sleeves, taking a pick axe and a spade and digging trial pits at the site of the proposed house. Your main aim will be to examine the kind of soil or rock formation that exists on your site. Before embarking on digging the trial pits it will also be prudent to find out if there are any service lines like electrical ducts, sewer lines, water lines or fibre optic cable lines that pass through the site and mitigate against damage to them. This might involve requesting the service providers to relocate them before starting construction. The trial pits investigation should yield three very important results namely; depth to firm strata, presence of ground water and type of firm strata. All of these have a direct bearing on the cost and type of foundation as well as the type of foul water disposal system that will be suitable for the house. It will be possible at this stage to tell for example whether to use a pad or a strip foundation on the house or whether to have a septic tank or a conservancy tank for the toilet water.

After determining the type of firm strata, the depth to firm strata, presence or absence of ground water and the type of soil on site; a building professional will be able to advise on the kind of foundation that should be used for the structure. Basically it will be the most economical and safe foundation option amongst the various types of substructure options that will suit the site conditions as well as the building design.

Most site soil conditions including the dreaded black cotton soil can be made to transmit the weight of a building. Bridges like the Mtwapa Bridge and the New Nyali Bridge at the coast have been made to pass over the ocean and still carry their own weight and the weight of vehicular traffic. I therefore find it’s nonsensical and comical for someone to suggest that house or a boundary wall has cracks due to the fact that it is built in an area that has black cotton soil. To paraphrase from Hosea of old who wrote centuries ago; your wall is cracking because of lack of knowledge. Don’t blame the ground or the weather.

Most of the enduring buildings and structures in Kenya have one thing in common; a firm foundation and knowledgeable construction techniques. When Giovanni Battista Cairati was commissioned to build Forte Jesus de Mombaça or Fort Jesus in Mombasa in 1593, he must have used his engineering knowledge and conducted a proper ground investigation before laying his foundation. He would have done the same if he had been commissioned to build the fort in Ruai or Kamulu and it is safe to assume that the fort would still be standing centuries later. Why pray tell does a simple two meter high masonry boundary wall built in Nairobi develop cracks a couple of months after it has been built? The answer to this boils down to the quality of the foundation, and the knowledge or lack thereof, of the builders.


Till next time, keep well and keep safe.

Fundi Mjanja.

Reducing Weight in Suspended Concrete Floors

Suspended concrete floors are found in storey buildings. The self-weight of concrete without additional live loads is great but buildings where the spans are large, weight reduction is done to avoid buckling of the floor. Buckling is where the concrete sags at the middle. The concrete is laid the same way but hollow blocks are added to reduce weight. The blocks are hollow in the middle and the reinforcements are laid in between them then concrete is added and vibrated to hold them together. The top concrete is about seventy six millimeters (three inch) thick.

The suspended concrete floor hollow blocks are either clay or concrete blocks. The blocks are two hundred to two hundred and fifty millimeters thick. The blocks that are at the beginning and at the end of a row are blocked on one side to avoid concrete from flowing inside the blocks. The ceilings from this kind of floors are flat and the ordinary down stand beams are not visible from below the slab soffits. These floors are ideal over big rooms like lounges, dinning and offices.

When the suspended slab form work is ready, the laying of the hollow blocks commences. The external beams are then laid into the forms. The internal beams for this kind of floors are laid within the slab thickness. These beams will span from the external ones across the room to the other end. The beams are also laid where walls are to be built on the slab. The hollow blocks are then laid on the form work in between the beams. They are arranged in rows of nine hundred millimeters wide with a spacing of a hundred millimeters in between the rows.

Once the hollow blocks are laid, the gaps in between are fitted with reinforcements. This bars span from the end beams and they are to hold the concrete together. A mesh fabric is then laid on top of the hollow blocks. After this is done concreting work commences. The concrete should be well vibrated to ensure the blocks are held tightly together. The concreting is done normally and is leveled and made smooth. Curing is done for twenty one days before stripping off the form work to pave way for plaster work.

Fundi Mjanja.

Laying Hardcore Under Concrete Floor Beds

Hardcore is the material put under floor . It is used as a sub base after building the foundation wall to make up levels before casting the ground floor concrete slab. The recommended kind of hardcore is hard stone ballast or quarry waste that should not pass a sieve of more than six inches when broken down. Care should be taken to ensure that the hardcore is free of weeds, roots, vegetable soil, clay, black cotton soil or other unsuitable materials. Broken stones or brick cuttings can also be used as hardcore.

To lay hardcore under floor beds, use well graded smaller pieces mixed with fine materials. This will give a dense compact mass after consolidation. It is laid in layers not exceeding two hundred and fifty millimeters of consolidated thickness. Sufficient fine materials shall be added to each layer to give a gradation necessary to obtain a solid compact mass after rolling. A ten ton smooth wheeled or two ton vibrating roller should be used to compact each layer.

Compact each layer with eight passes of the roller when laying hardcore under floor beds. Add sufficient water with every pass to obtain maximum compaction. To each layer add a fine layer of sand or quarry dust forced into the hardcore by a rolling vibrator. All the materials used must always be dry to avoid caking or stickiness as this may allow pockets of air or free spaces which may result in sinking when the hardcore is loaded with weight. If the sand or quarry dust is absorbed into the holes between hardcore then keep compacting.

Thoroughly compact the hardcore filling under floor beds until sand or quarry dust is not absorbed. The top surface should be made level. The levels are done or graded to the required falls. After this is done a blinding layer of at least twenty five millimeters in thickness is added. A ten ton roller is used to level the surface. After the mass of hardcore has been compacted and rolled to the right level anti-termite is applied to the surface. Damp proof membrane and mesh reinforcement material are then laid on the surface in readiness for concreting of the slab.

Fundi Mjanja.

ERECTING A CONCRETE COLUMN

Erecting a Concrete Column

Concrete columns are used for carrying loads of a building. They transfer the same to a suitable soil bearing capacity. They carry loads horizontally, vertically and laterally. They can be erected as free standing, used for hanging gates. Alternatively they can be incorporated within the walls of a building structure. Concrete columns are made from steel and concrete cast in a form work. Columns can be circular, rectangular or square shapes.

In erecting concrete columns the load to be carried is considered. This determines the size of column and type of reinforcement to use. The process of erection commences by setting up a base. A pit is first excavated to a suitable soil bearing capacity in depth. Blinding to the pit is done to protect the soil touching the steel reinforcements. When the base is cast, some steel reinforcement is left exposed. This is used as starter bars for the column.

Form work of the required column size is formed first aside. The already tied steel is joined together with the starter bars. This ensures the column starts from the ground upwards. The steel should be free from oils and rust. Use binding wire to tie together all steel.. When the steel work is complete, then form work assembly starts.

The form work for erecting a column is fixed by opening the sides. It’s then slid to have the steel inside the box. When fixing the form work care must be taken to ensure that the steel reinforcement is not in contact with the casement. Allowance should be left between the steel and the form work casement to allow the concrete to cover the steel all round. Once the box is upright, the form work is then fastened and supported on all sides. Concrete is then poured and vibrated until it reaches the top of the box. It is important to cast concrete in lifts as you vibrate. This should not exceed two thousand five hundred millimeters in height. The form work casement is then left on for seven days as curing take place. Curing is done from the top. After seven days the form work is then removed to expose the cast column. This is continuously cured for another seven days.

Fundi Mjanja.

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