In earlier times, land was readily available and buyers could opt out of buying plots with black cotton soils in favor of others with better soils. Currently, the land available has become scarce and expensive so buyers have no choice but take what is available.

Black cotton soil is found abundantly in most regions in Kenya. For example in parts of Kajiado, Nairobi, Rift Valley, Kiambu, Machakos, and Nyanza. Within the Nairobi metropolitan area this type of soil is common in Kitengela, Syokimau, Athi River and even Kamulu areas along Kangundo road.

Why is it risky to build Foundations in Black Cotton Soil?

Black cotton soil, a cohesive soil, is considered a problematic soil for civil engineers. It has characteristics of swelling during rains and shrinking during summer. In both the conditions, it poses problems.

The continuous expansion and shrinkage of the soil creates a very unstable environment to build a foundation on. It is what causes the cracking in floors and walls due to the uneven settlement in foundations.

Special care must be taken into consideration when building foundations on this type of soil. This is why the cost of building is usually higher in these soils.

How should you build on black cotton soil?

There are two common ways of dealing with the soil: one can excavate all of it or have a floating foundation.

Option 1: Mass Excavation

When building on land with black cotton soil, the entire top soil is always removed through excavation using building machinery.

Once the soil has been excavated, you can start construction using the normal strip foundation that is common for residential houses.

The additional costs that the homebuilder incurs here include the costs of hiring an excavator, transportation costs of the excavated soil, and backfill materials.

Option 2: Using floating foundations

Generally, if the black cotton soil is more than 1.5m in depth and the homebuilder has no intention of creating a basement, it becomes uneconomical to excavate the whole of it.

This requires a suspended type of foundation whereby columns are dug till solid rock or firm ground and protrude slightly above the ground level.

The suspended type of foundation is known as the pad foundation. Here excavation will be done only for the load-bearing components of the house, which are the columns and ground beams. These columns and beams will then support the entire structure above the soil near the surface.

Waste water management

Black cotton soil has poor drainage. When constructing soak pits in the terrain with this type of soil, water doesn’t percolate. In stead it stagnates on ground. 

In such areas its advisable to fill in the soak pit with large sized quarry chips to make the soakage faster. Alternatively the soak pit will have to be dug deeper till one reaches the stone.

Please ensure you engage a professional before undertaking any building project.

Need help with your construction project? Talk to us

The post How to Build on Black Cotton Soil appeared first on My Building Code.

Kenya lies in the equatorial zone receiving plenty of sunshine all year round. This makes solar a very viable source of energy. If you were thinking of making the switch to solar, here is all the information you need:

1. Types of Solar Panels
   • Solar Thermal Panels
     • Pricing of solar water heating systems
   • Solar PV Panels
2. How Solar PV Systems Work
   • The Solar Module
   • Inverter
   • Solar Battery
   • Charge Controller
   • Load, Cabling and Connections
3. The Different Solar PV Systems and their associated costs
   • Plug and play Solar Kits
   • Component Based Systems

Types of Solar Panels

There are two types of solar panels:

1. Solar Thermal Panels

Solar Thermal is usually used for water heating. It’s a simple technology with three key components:

• Collectors: These are the solar thermal panels mounted on your roof. They absorb sunlight and transfer its heat to a fluid. Flat plate collectors and evacuated/vacuum tubes are the most popular types of collectors. The vacuum tube is more efficient in that it works on the thermos principle: therefore very little heat is lost.
• Pump & Controller: The pump ensures the transfer fluid is circulated between the collectors and the water cylinder efficiently.
• Water Cylinder: the panels on your roof are the collectors of sunlight, thus heating up the liquid in the tubes which is then transported into your cylinder ready for use.

Pricing of solar water heating systems

The cost of installing a solar thermal/ water heating system will depend on the brand and the type of solar water heater, i.e. whether it’s flat plate or evacuated tubes, pressurized or non-pressurized system. The prices range from Ksh 50,000 (USD 425) to an upwards of Ksh 200,000 (USD 1,700).

Note: Installation of Solar water Heaters in Kenya is guided by the Energy and Petroleum Regulatory Authority (EPRA), thus it is important that your installation is handled by an individual with the certifications required by EPRA.

2. The Photovoltaic solar panel (Solar PV)

Solar PV converts sunlight into electricity and can be used to power appliances. Read more about how the solar PV panels work here.

The Solar PV has a higher capital cost than solar thermal. Solar PV also requires larger area of space for installation compared to solar thermal.

Still, the solar PV has a big advantage over solar thermal in that it generates electricity. This allows solar PV owners to sell excess electricity back to the grid and generate a sustainable second income.

The choice between the two will depend on your needs. But we’ve seen many households opting to install both types of solar, utilizing the solar thermal panels for hot water and the solar PV for electricity generation.

How Solar PV Systems work

We’ve already explained how the solar thermal panels work so for the rest of the article we shall focus mostly on solar PV system and its various components.

The Solar Module

The Solar PV panels, also referred to as solar module, is made of photovoltaic (PV) cells. Solar radiation emitted by the sun is absorbed by the PV cells when the sun shines directly on them.

Most PV cells have two layers of semi-conductor material, one positively charged and one negatively charged. When light shines on the semi-conductor the electric field across the junction between these two layers causes electricity to flow, generating direct current (DC).

Note: Solar PV electric panels do not require bright sunlight in order to operate, meaning you can still generate electricity on cloudy days. However in general, the greater the intensity of light the higher the flow of electricity

Inverter

Direct Current (DC) needs to be converted into alternating current (AC) so it can be used in a domestic building; this is performed by an inverter. Once converted, the AC current is fed into the electricity supply for use in the home, with any surplus electricity fed back into the national grid.

Solar Battery

It is important to realize that you can only use your free solar electricity when it is being generated – but if you invest in solar batteries you’ll be able to store power for use in the evenings and at night when the panels are not producing electricity.

Charge Controller

The charge controller serves as a current and/or voltage regulator. It ensures that the solar batteries are not overcharged during the day, and that the power doesn’t run backwards to the solar panels overnight and drain the batteries. Some manufacturers put the charge controller and inverter into one thing for simplicity.

Load, Cabling and Connections

In solar terminology, the term “load” refers to the power consumption of the device(s) that are being used in the system. Understanding your loads is critical to maintaining a well functioning power system.

The loads will determine the size of cables that will be used. Cabling for solar done wrong will most definitely burn your house down. The right size of cable from PV to charge controller, and from charge controller to battery is absolutely necessary.

The way they are connected is solar panel to charge controller to battery + charge controller to DC loads + charge controller to inverter to AC loads. And that’s what a solar system is.

The different Solar PV systems and their associated costs.

Plug and Play Solar Kits

These are relatively inexpensive kits capable of providing lighting and power for AC & DC applications anywhere. They come ready to use, with preinstalled accessories: you just just plug and play.

Their installation costs are minimal since once you purchase, you can either ask for someone to put it on your roof or do it yourself.

The cost for the kits will vary depending on the accessories and payment method. A spot check across various manufacturers show the average retail price of a simple PV system with solar panel, battery, a couple of light bulbs, radios and torch will range between Ksh 35,000 (USD 300) – Ksh 45,000 (USD 385). If the accessories include a TV etc, the price will be higher.

Some sellers offer a ‘Pay-As-You-Go’ financing model where you pay a deposit and monthly installments.

The main disadvantage with these kits is that it comes attached to its own loads i.e. bulbs, TV etc. You can’t add your own to the system. This is why some people opt for Component Based Systems (CBS).

Component Based Systems

For CBS you buy the components separately and they are assembled to form a household solar system like the one we described here.

For CBS installation, you’ll need to involve a solar practitioner who is licensed by the Energy and Petroleum Regulatory Authority (EPRA)- the Kenya Energy Regulator. You van verify the practitioners license from the EPRA website. Incase of issues, you can lodge a complaint with EPRA and they’ll send an inspector.

It is not recommended that you buy the solar panel and other components off the shelf then just connect them together. EPRA technicians need to design the system for you based on the loads you want to be powered.

The cost of installing a CBS, Solar PV system will depend on the loads, size of the inverter and size of the battery. The price on average typically starts from Ksh 90,000 (USD 770) for a 2KVA Inverter, 100Ah Battery that will be sufficient for lighting and WIFI needs running on single phase power. The more the loads the higher the price.

Note: Powering all loads you have with solar might be costly. A good technician will advise you to start with the crucial loads. This will be more affordable as opposed to doing the whole house.

Got any questions regarding solar? Type below in our comments section.

The post A Cheat Sheet for the Best Solar Panels to install for Your Home appeared first on My Building Code.

Whereas every home has some level of risk for flooding, there are several things that you can do to help minimize this.

We have listed down some tips to follow during construction that will assist in draining the excess water that comes during storms.

1. Location

One of the best ways to protect houses from flooding is by paying careful attention to the location of your home. In a previous article, we wrote extensively on what to look out for when purchasing land with an intention of building.

By all means avoid flood prone areas. Ensure the topography of the piece of land will allow you to drain away water. This could be because either the soil doesn’t pool up water or that the property is slightly sloped, or is highly elevated so it doesn’t collect much water.

2. Flooding prevention when Building near a water way

Mother nature can be very unforgiving if you encroach on what’s rightfully hers. That’s why it is very important to carry out site surveys before construction, including checking any available flood data from meteorological department if you are to build next to lakes, rivers, dams and swamps.

Government regulations require a developer to leave enough space between the boundary wall and a water body. In most cases, developers use the six- to 30-metre rule (above the high water mark) under the Environmental Management and Conservation Act.

3. Build above the road level

The ground floor slab (also referred to as a plinth) is normally constructed just above the ground level and immediately after the foundation. It raises the floor above the ground level, preventing surface water from entering the building.

Under no circumstance should the plinth level of your building become lower than the adjoining road level since you will be unable to discharge storm water during rain from your plot. The water would get collected in the plot and the land would remain submerged till the water dries out.

It is also advisable to keep the land sloping downwards towards the road, so that water will drain out faster.

4. Storm water Drainage Systems

When rain hits the hard, impervious surfaces associated with modern life – driveways, sidewalks, streets, rooftops, parking lots –it should be channeled towards storm water drainage systems.

Such systems should be well maintained since if they get backed up, then rain will build up instead of flowing away from your home. Regularly clean your gutters and downpipes to prevent water from pooling around your foundation. It’s also important to keep your ditches and drains clean so they don’t overflow.

5. Landscaping

The increase in population means that we are building more and reducing the land where runoff water used to drain. Instead of building up the whole area, you can leave some land where water can seep through the ground.

You can eliminate paved surfaces or install alternatives by incorporating green infrastructure such as planting gardens and trees in your lawns instead of having impervious concrete/tarmac in paths, patio or areas surrounding your home.

Alternatively you can opt to use a “porous pavement” made from interlocking cement blocks that allow spaces for rainwater to seep into the ground. If you must pour concrete, keep the paved area as short and narrow as possible.

The post Flooding: 5 Proven Construction Techniques Which Reduce the Vulnerability of a Building to Floods appeared first on My Building Code.

Consequently, many millennials would opt for light gauge steel technology if they were made to understand the myriad of opportunities it presents. Sure, we all know about structural or heavy steel as a common construction material favored for large construction projects without which, skyscrapers wouldn’t be in existence.

Steel, unlike masonry, wood and other construction support materials, has a terrific strength-to-weight ratio and is very flexible: it can bend without cracking. That’s why a steel building can flex when pushed to one side either by great wind pressure or an earthquake.

Light gauge steel construction gives you speed, strength and sustainability at a fraction of the weight and at a more affordable cost compared to conventional construction. The difference between structural steel and light gauge steel lies in how they are manufactured.

Light gauge steel sections are cold formed sections, meaning that the sections are shaped into strong “C” or “Z” forms, capable of holding heavy loads, at room temperature.This is in contrast to thicker hot rolled sections, that are shaped while the steel is molten hot to form structural steel.

Light gauge steel is then coated with zinc (called galvanized) to protect it from corrosion. From the manufacturing process, lower production costs are realized since LGS does not involve heat input and its associated expense.

The foundations for an LGS structure will be similar to the conventional masonry building method for example strip footings etc. but will require less reinforcement because steel frames are lighter than masonry frames.

In construction, time equals money. LGSF system, design, production & shipping can happen within days or weeks, instead of months. Because most of the construction components are manufactured in the factory, frame erection and construction at site can begin immediately due to the pieces being exact specification, pre-cut, pre-punched & pre-marked.

No additional work to be done at site. Additional advances in the speed of projects are attributed to the near 100% computer controlled accuracy(+/-0.5mm) of the frame ensuring a near 100% square and straight frame which benefits other trades. Its lightness makes for easy handling on site that contributes to faster erection.

The uptake of LGS in Kenya is now fast growing with developers mainly testing it as a truss structure replacing traditional timber trusses. Unlike wood, steel is stronger and more durable.Steel does not burn or rot and is not susceptible to moisture damage, termites or other wood destroying insects.

It helps preserve our environment for the future by decreasing the consumption of wood. It is 100% recyclable, can be used again and again, without losing its properties.

An economical LGS frame system is increasingly being used in America, Europe, Australia and New Zealand as a serious alternative to lumber in residential construction where wood frame construction was previously popular.

Light gauge steel framing has a few minor disadvantages first being with regard to its fire resistance properties. Although noncombustible and thus will not fuel the fire, the steel studs are directly affected by high temperatures.

Since there is not much mass to the steel studs and joists in this type of construction, the steel trusses and bar joists are likely to be weakened quickly by heat and are prone to early collapse.

An easy way to work around this is ensuring the steel is clad by fire resistant material and provide cavity insulation material.This will protect the steel sections from heating up rapidly when exposed to fire.

The issue of thermal conductivity has been a concern especially since steel is a good conductor of heat. This could potentially result in increased heating costs in cold climates, and in hot climates heat gain could result in moisture damage. Again, insulation placed between the steel frame (batt insulation), will give a better overall thermal performance of LGSF walls.

The pros far outnumber the cons and the technology can be widely used in residential, commercial, and industrial construction.

The post Construction in the digital age: a glimpse into light gauge steel technology appeared first on My Building Code.

Traditional methods of construction, no matter how efficient you try to be, simply cannot compete with the advantages offered by modern technologies. By traditional, we are referring to masonry construction and in situ concreting of structures. These are not only labor intensive but have the disadvantage of being adversely affected by weather conditions.

The weight of masonry blocks, or even concrete structures increase the dead load that has to be sustained and taken safely to the foundation, hence will require a much more elaborate structural design in the form of more reinforcement, bigger columns, deeper beams etc.

Technicalities such as setting up of formwork and reinforcement and erecting of scaffolding take up a lot of time and add on to the complexity of the process. Work on lower levels cannot proceed before scaffolding can be removed (in about 3-4 weeks), further delaying the project.

Modern trends in the building and construction industry are leaning towards light weight construction and a shift from using natural building materials to more man made and composite materials with increased levels of fire safety. Off-site pre-fabricated construction is also being encouraged for more efficient use of these material and further reduction of build times. The bottom line is to save on time and ultimately cost but not to compromise on quality.

EPS panels

The National Housing Corporation, in a bid to develop decent and affordable housing in Kenya, introduced expandable polystyrene (EPS) panels to the Kenyan market. The EPS panels are an innovative building material consisting of EPS foam sandwiched between a galvanized steel wire mesh that provides for lightweight construction with excellent insulation properties.

Each panel is 3.0×1.5 meters wide and is a substitute for building stones and timber and take less time to erect. This means that they might very soon replace the traditional reinforced concrete and masonry in both horizontal and vertical parts such as roofing, walling and flooring. They are finished by plastering on both sides.

Steel frame construction

Steel frame construction is one of the building techniques that have made construction of sky scrapers possible. The skeleton of the building will consist of vertical steel columns and horizontal I-Beams constructed in a rectangular grid to support the floors, roof and walls of a building which are then attached to the frame.

The frame needs to be protected from fire because steel loses its strength at high temperatures and can cause a building to collapse.

Construction is quick and simple mainly since fabrication is carried out off site.

Steel as a building material is more durable, compared to wood, since it is not susceptible to termites and other pests. It is also able to span greater distances enabling design flexibility.

It has the highest strength to weight ratio of any construction material and is also a recyclable product.

Shipping Container Homes

Shipping containers that are normally ferried on trailers are now being used to make homes. Aside from being very affordable, they have an added advantage of being portable meaning if you want to sell the land, you can relocate your container somewhere else.

The shipping containers are modified and refitted to fit the user’s interest. The prefabricated container house can be used as an office, shop, or home. They even come complete with installed plumbing and electrical system.

The size of container, age and condition will influence the price of the container. The number of add-ons or customized features that you go for in the shipping container will also contribute to your overall construction cost.

The post How to Build a House in Ten Days appeared first on My Building Code.

Climate change has stopped being a theory that we read about in books and is now a harsh reality. Human influences are thought to be the main cause behind the rise in global temperatures.

Global warming is defined as the gradual increase in the overall temperature of the earth’s atmosphere generally attributed to the greenhouse effect caused by increased levels of carbon dioxide and other pollutants. This has resulted to rising sea levels, stronger hurricanes and storms and greater frequencies of floods and droughts.

Extreme weather conditions are likely to become the new normal.The summers are getting hotter and the winters colder. There is need to ensure our buildings are well adapted to climate change to ensure an efficient indoor climate control. Ideally, the level of thermal comfort indoors should be maintained regardless of the fluctuating weather conditions on the outside with little or no use of mechanical devices.

Houses are built primarily with the intent of providing shelter from harsh weather conditions. Careful thought as to how you build your buildings envelope may be the difference between a relaxed and productive atmosphere and the discomfort that arises from a dissatisfying thermal environment.

The sun is an important source of renewable energy available today and the best part about it is that it is absolutely free and clean. Right from the design stage, one can take advantage of solar energy by ensuring the design of your house permits maximum entry of solar energy in the form of heat in the winter and minimum entry during summer.

This is what is referred to as passive solar heating and it has everything to do with how you orient your building on site, and how you determine the position and size of your windows.

The rule of thumb is to locate your windows on the side that is facing the equator.

That means that for a building located in the northern hemisphere, the general direction to receive sun throughout the day would be to face the windows towards the south but if it is located within the southern hemisphere, face the windows of the structure to the north.

East/west facing windows are normally avoided since they will experience the most solar heat gain and glare from direct sunlight entry but if you must have them, either minimize their sizes or provide for appropriate shading methods.

In the equatorial location, if solar heat gain is to be avoided, the main windows should face either north or south, depending on the exact site location.

You can never go wrong with trees.A part from aesthetics, trees will not only provide adequate shading for your building hence reducing solar gain especially in the hot afternoons but ensures further cooling takes place when water evaporates from the leaf surface.

Go for deciduous trees since they block the sunlight in the summer and allow us to receive the much needed warmth and light during the cold days.

They are also a natural air conditioner since they absorb carbon dioxide and potentially harmful gases such as carbon monoxide from the air and release oxygen.

Trees can also be used as windbreakers by reducing wind speed and subsequent loss of heat from your home. Heat transfer through a buildings envelope takes place through conduction, convection and radiation.

Ideally, heat will flow from an area of high temperature to lower temperature. The greater the temperature difference, the greater the heat flow through an assembly.

To make a building more comfortable, we need to impede these modes of heat transfer. Insulators placed between conductors will slow down heat transfer. The materials used to make a buildings elements are worth taking into consideration in order to adequately address the issue of thermal comfort.

Metals such as steel and aluminum are the most common conductors. Their greater rate of heat flow can be taken advantage of as pathways for heat to flow to colder areas. The key is in moderation, know where to use which material and how to best take advantage of its thermal properties or lack thereof.

This article was first published under the heading “Not too hot, not too cold” and has since been edited

The post Sustainable Building And How To Adapt To Climate Change appeared first on My Building Code.