Clerk of works

Clerk of works

Posted By: Blue Print Blog on 7th of November 2013

The Clerk of Works often abbreviated CoW, is employed by the architect or the client on a construction site with the primary responsibility of representing the interests of the client on the project. In addition to recognizing the quality standards of the work the CoW is also charged with ensuring that the quality of both materials and workmanship are in accordance with the design information such as specifications and engineering drawings. The qualification for clerk of works can be held in three specializations: electrical, mechanical and construction. Historically the clerk of works was employed by the architect on behalf of a client or by local authorities to oversee public works. But in modern era the CoW can also be employed by the client (state body/local authority/private client) to monitor design and build projects where the traditional role of the architect is within the design and build project team.  The role The role of this position is based on the impartiality of the clerk of works in ensuring that value for money for the client - rather than the contractor - is achieved through rigorous and detailed inspection of materials and workmanship throughout the building process. He should be independent in decisions and judgments. He cannot normally, by virtue of the quality role, be employed by the contractor –but only the client or normally by the architect on behalf of the client. His role is not to judge, but simply to report all occurrences that are relevant to the role.  In many cases, the traditional title has been discarded to comply with modern trends, such as site inspector, architectural inspector and quality inspector, but the requirement for the role remains unchanged since the origins of the title. Clerks of works are either on site all the time or make regular visits. They need to be vigilant in their inspections of a large range of technical aspects of the work. The role involves; Making sure that work is carried out to the client's standards, specification, correct materials, workmanship, and schedule. Becoming familiar with all the relevant drawings and written instructions, checking them, and using them as a reference when inspecting work. Making visual inspections. Taking measurements and samples on site to make sure that the work and the materials meet the specifications and quality standards. Being familiar with legal requirements and checking that the work complies with them. Having a working knowledge of health and safety legislation and bringing any shortfalls observed to the attention of the resident engineer. Advising the contractor about certain aspects of the work, particularly when something has gone wrong, but this advice should not be interpreted as an instruction.

Glass Blocks

Glass Blocks

Posted By: Blue Print Blog on 31st of October 2013

Glass block is an architectural element made from glass and they are used in a building to add beauty while at the same time to provide visual obscuration while admitting light. The glass block was originally developed in the early 1900s to provide natural light in manufacturing plants but over the years it has been considered as an element of interior design commonly applied as part making the interior of the house more appealing to the eye.  Glass bricks are produced for both wall and floor applications. Glass blocks for use in floors are normally manufactured as a single solid piece, or as a hollow glass block with thicker side walls than the standard wall blocks. These blocks are normally cast into a reinforced concrete grid-work or set into a metal frame, allowing multiple units to be combined to span over openings in basements and roofs. Glass wall blocks should not be used in flooring applications. Hollow glass wall blocks are manufactured as two separate hemispheres and, whilst the glass is still molten, the two hemispheres are pressed together and annealed. The resulting glass blocks will have a partial vacuum at the hollow centre. Glass wall blocks in a house are erected after the floor and wall finishes are completed can be erected in short walls of three feet high to full height walls. They can be used to divide an entry porch and a sunken lounge or dinning. The blocks can also be used in a niche that provides light into a dark lobby as well as in the bathrooms as cubicles or for beauty since have they have good aesthetics. When installing glass blocks the area to be walled should be clean and free of any debris and dust and the abutting masonry should have the plaster complete as the blocks will be an in fill as they are not load bearing. The wall can be reinforced on the sides with aluminum frames to house doors or openings.  The bonding should be carefully done in accordance to the manufacturer’s instructions.  The most commonly used bonding agent with glass wall blocks is Silicon. Care should be taken to ensure that every part of the joint is filled with the adhesive. When all the courses are complete to the desired height the top of the wall can be finished with timber, aluminum or rubber rails. The top finishing is used as a protection for the glass block and can also be used for holding small flower pots, portraits, paintings or any other interior beauty enhancing objects.

Building a Safe Staircase

Building a Safe Staircase

Posted By: Blue Print Blog on 24th of October 2013

The staircase in a building is one means whereby one may travel from the level of one floor to another. The ease with which a stairway can be traveled depends upon the proper proportioning of the riser and tread of each step and the number of steps in one series or flight. The design of the building and the space allowed for stairs will control the type of staircase which may be built. The staircase, when carefully designed and built, adds dignity and charm to a home. The quality of craftsmanship displayed reflects the character of the entire interior of the building. In general, stair-work is considered a special field of carpentry. Stairways can be the cause of the greatest number of accidents in the home. These accidents can be attributed to various factors; some, of course, are beyond the control of those who design and build the stairways. However, there are far too many accidents due directly to faulty construction. The carpenter can make a worthwhile contribution toward accident prevention if he plans and does his work well. The following standards and suggestions should be observed when building the staircase to help avoid some of the causes responsible for the accidents; Stairways should be free from winder The dimensions of landings should be equal to or greater than the width of stairways between handrails (or handrail and wall) Landings should be level and free from intermediate steps between the main up flight and the main down flight. All treads should be equal and all risers should be equal in any one flight. The sum of one tread and one riser, exclusive of the nosing, should not be more than 18 inches nor less than 17 inches. (Stair ratio). The nosing should not exceed 13/4 inches. All stairways should be equipped with permanent and substantial handrails 36 inches in height from the center of the tread. All handrails should have rounded corners and a surface that is smooth and free from splinters. The angle of the stairways with the horizontal should not be more than fifty degrees nor less than twenty degrees. Stair treads should be slip proof, firmly secured and with no protruding bolts, screws, or nails.

The Collapse of Buildings

The Collapse of Buildings

Posted By: Blue Print Blog on 17th of October 2013

Buildings, like all structures are designed with special attention to allow the support certain loads without deforming. The loads that are taken into account during the design stage of any building include both live loads and dead loads like furniture and equipment. For a building to be declared safe for occupation it must be able to withstand the weight of rain and the pressure of wind as well as bear the load of the building itself. Buildings that comprise fewer floors, strength generally accompanies sufficient rigidity and the design is mainly that of a roof that will keep the weather out while spanning large open spaces. With tall buildings that consists of several floors the roof becomes a minor matter and the support of the weight of the building itself should be the main consideration since just like long bridges, tall buildings are subject to catastrophic collapse if considerable care is not taken during the design stage. The main causes of collapse in buildings can be generally classified under the following; Bad Design Faulty Construction Foundation Failure Extraordinary Loads Bad Design Bad design due to errors of computation and failure to take into account the loads the structure will be called upon to carry, erroneous theories, reliance on inaccurate data, ignorance of the effects of repeated or impulsive stresses, and improper choice of materials or misunderstanding of their properties may easily result into a collapse of the building. The engineer should take a keen interest during the design stage as he is bound to be held responsible in the event of these failures. Faulty construction Faulty construction has been the most often cause in recurrence of structural failure. This may occur due to mistakes arising from lax in inspection which includes the use of salty sand during concrete mixing, the substitution of inferior steel for that specified, bad riveting or even improper tightening of nuts, bad welds, and other practices well known to the construction worker. Foundation Failure Even an excellently designed and constructed structure will not stand on a bad foundation. Although the structure will carry its loads, the earth beneath it may not. The Leaning Tower of Pisa is a famous example of bad foundations but it is not the only one. The old armory in St. Paul, Minnesota, sank 20 feet or more into soft clay, but did not collapse. The displacements due to bad foundations may alter the stress distribution upon the building significantly. Extraordinary Loads Extraordinary loads are often natural, such as repeated heavy snowfalls, or the shaking of an earthquake, or the winds of a hurricane. A building that is intended to stand for some years should be able to meet the challenges of extraordinary load that may arise from frequent earthquakes and strong winds. Even a solid masonry building would be destroyed in an event of earthquakes if the foundation is not designed carefully to withstand external natural strains.

Building Demolitions

Building Demolitions

Posted By: Blue Print Blog on 3rd of October 2013

Demolition projects can range from small, simple jobs to complicated undertakings that require sophisticated and detailed planning. Site conditions can vary significantly, and there is always a degree of imprecision to the wrecking of the building itself. For typical building demolition and site improvements the most common procedure is to use heavy mechanical equipment such as wrecking balls, excavation hoes, grapples, crushers, and hydraulic breakers and shears. Several factors need to be considered prior to and during demolition, including the scheduling of demolition activities, protecting the site (especially important with occupied structures), and dealing with hazardous materials. With the demolition of structures, the owner, architect, engineer and demolition contractor need to be aware of the regulations that govern the demolition of buildings. Prior to allowing the demolition squad to start demolition operations, an engineering survey of the building that is marked up for demolition should be carried out by a competent and qualified person to determine the condition of the framing, floors, and walls, and possibility of unplanned collapse of any portion of the building. The demolition team should have in writing evidence that such a survey has been undertaken and the demolition process has been given a go ahead from the relevant authorities. Building demolition can include items that may not be apparent at first such as any below-grade structures that would include various types of footings and foundations. Also underground utilities that provided services to the building and the adjacent buildings will need to be considered during demolition. In rural areas--where buildings are not densely packed--and the built structures themselves are often smaller with fewer recyclable materials, demolition is usually uncomplicated, in that the structure can be knocked down and the debris can be removed all together but in urban and densely packed areas, demolition projects may require the hiring of an architect or engineer to produce documents, drawings, and specifications for building demolition. Contractors who specialize in demolition need to come up with a demolition schedule to manage the project. If the owner will be occupying a portion of the site or building during demolition, a schedule of demolition activities will be useful to avoid interference with any concurrent operations and to minimize any disruption of utilities and services. The owner may have additional restrictions that the contractor will need to consider when scheduling activities. Some typical owner restrictions include the protection of exterior stairs, loading docks, and entries of adjacent buildings, as well as a limitation on hours during which demolition operations may take place. However, every additional restriction the contractor needs to manage will usually be reflected in higher demolition costs. In areas with greater population density, the demolition of structures is not necessarily more complicated. Some situations are complex and mandate a high level of sensitivity to how demolition is handled, for example, demolition that takes place on a hospital campus. In these instances, a careful, piece-by-piece dismantling of the building is usually necessary, with material sorting often taking place on site. For such projects, an engineer or architect will need to be consulted to produce specifications to which the demolition must conform. The architect or engineer will produce the necessary documents which clearly outline the requirements for protecting individuals, adjacent buildings, and any remaining site improvements and utilities during the demolition operations.

Quality Construction of Suspended Floors

Quality Construction of Suspended Floors

Posted By: Nyumba Imara Blog on 7th of November 2013

Building suspended floors that are acceptably flat and level is one of the many challenges that contractors may have to face in the course of a project construction. Whether supported by steel beams or a cast-in-place concrete frame every elevated floor deflects or sags slightly under its own weight. Structural drawings generally require that individual floor framing members have a slight camber, or hump in their profile prior to construction so as when cambered floor framing members are allowed to deflect they ideally will move to a level position. When everything works right, the floor’s finished surface will then perfectly complement structural deflection. Forms and shoring should be designed to allow safe, easy removal, while protecting the structure from excessive deflections at early stages. However buildings come in many shapes and sizes and as the available materials and floor framing are assembled together unique combinations are created thus the resulting floor systems do not always deflect to the engineer’s expectations. That's why the successful contractor must remain flexible and be ready to respond to jobsite developments. Success depends on two things—an effective preconstruction planning program and the ability to identify and adjust to unexpected conditions. Monitoring the Construction The goal in constructing any project is to meet and if possible exceed the requirements of the specifications. When evaluating construction of floors, the following standards, depending on the structural system should apply; Structural steel must be properly erected Steel connections must conform to the contract document requirements Concrete reinforcement must be placed and maintained in the proper location Concrete mix design, strength, and slump must conform to the specification Finished floor surfaces must meet the specified tolerances for levelness and flatness. The following are essential elements to be put in place so as to achieve a quality suspended floor; Preconstruction planning and meetings to minimize potential problems Gathering information during construction to allow evaluation of the work Responding to unexpected results by adjusting the design or construction Confirming that the adjustments are successful. Controlling quality Controlling the elevation of the supporting platform requires that engineering controls be established. The monitoring program for a structural steel frame provides key information about critical components such as base plate, column splice, and beam-to-column connection elevations, along with deflection of typical framing members. On a cast-in-place concrete frame, the contractor should select forming and shoring systems. Forms and shoring should be designed to allow safe, easy removal, while protecting the structure from excessive deflection at early stages. Evaluating concrete mix designs, delivery systems, and finishing techniques provides an opportunity to achieve the quality standards. Each decision will impact the flatness and levelness of the finished floor. Concrete mixes must develop adequate strength while providing good consolidation, consistent set time, and workability. The workers involved on the project must be capable of producing work that conforms to the quality standards. Concrete finishing techniques must produce the desired results. The pre-construction meeting is a good opportunity to address the team's plan for coping with isolated locations where actual deflection of the floor might be different from what is expected. Discussing job site controls for structural steel, form-work, reinforcing steel, concrete, and finished surface profiles will help ensure that backup systems are ready. Changes and substitutions in materials or admixtures should not be made without notifying and obtaining approval by the rest of the design/construction team.

Common Plaster Problems

Common Plaster Problems

Posted By: Nyumba Imara Blog on 31st of October 2013

When plaster dries, it is a relatively rigid material which should last almost indefinitely. However at times the plaster work may start cracking due to several conditions.  Some of the conditions that may cause the plaster to crack, efflorescence (that is to lose moisture and turn to a fine powder on exposure to air), separate, or become detached from its lath framework include; •    Structural problems •    Poor workmanship •    Improper curing •    Moisture Structural Problems 1. Overloading Stresses within a wall, or acting on the house as a whole may end up creating stress cracks. Appearing as diagonal lines in a wall, stress cracks usually start at a door or window frame, but they can appear anywhere in the wall, with seemingly random starting points. The weight of the roof, the second and third stories, the furniture, and the occupants may impose a heavy burden on beams, joists, and studs. Even when houses are built properly, later remodeling efforts may cut in a doorway or window without adding a structural beam or "header" across the top of the opening. Occasionally, load-bearing members are simply too small to carry the loads above them and may lead to deflection or wood "creep" (deflection that occurs over time) thus creating cracks in plaster. Overloading and structural movement combined with rotting floorboard, rusted nails, or poor quality plaster results in the plaster detaching from the lath (floorboard) therefore losing its key. When the mechanical bond with the lath is broken, plaster becomes loose or bowed and if repairs are not made, especially to ceilings, gravity will simply cause chunks of plaster to fall to the floor. 2. Settlement/Vibration Cracks in walls can also result when there is settlement in a house. Houses built on clay or black cotton soils are especially vulnerable to cracks when settlement occurs as clay soils are highly expansive. In the dry season, water evaporates from the clay particles, causing them to contract. During the rainy season, the clay swells thus causing a building that is not structurally sound to be riding on an unstable footing. Diagonal cracks running in opposite directions suggest that house settling and soil conditions may be at fault. Similar symptoms occur when there is a nearby source of vibration-blasting or busy highway. 3. Lath Movement Horizontal cracks are often caused by lath movement. Because it absorbs moisture from the air, wood lath expands and contracts as humidity rises and falls. This can cause cracks to appear year after year. Cracks can also appear between rock lath panels. A nail holding the edge of a piece of lath may rust or loosen, or structural movement in the wood framing behind the lath may cause a seam to open. Heavy loads in a storage area above a rock-lath ceiling can also cause ceiling cracks. Errors in initial building construction such as improper bracing, poor corner construction, faulty framing of doors and windows, and undersized beams and floor joists eventually manifest through to the plaster surface.

Testing Drainage Pipes After Laying

Testing Drainage Pipes After Laying

Posted By: Nyumba Imara Blog on 24th of October 2013

Drains must not be covered over until they have been inspected and tested for leaks and the the joint performance. Two tests, a roughing test and a final test, should be applied to the drainage system in every building. The roughing test may consist of a water test or an air test, The water test is the one most commonly used, and during warm weather is the most convenient test to apply. It cannot, however, be applied conveniently in cold climates. The water test is applied by closing all openings to the drainage system, except those above the roof, and filling the system with water until it overflows the vent stacks. It is a more severe test than an air test and also a more unevenly distributed one. To apply a roughing test it is necessary to close all openings to the system. Lead closet bends, and all lead pipes or traps that project from floors or walls should be closed by soldering a round disk of sheet lead over the opening. This should be done at the time of installing the lead work to prevent anything entering the drainage system and also to preserve the shape of the outlets for the walls and floors to be fitted to. Openings to wrought-iron drainage systems and wrought-iron vent pipes can be closed by means of screw plugs or capped nipples. When necessary to extend an outlet from behind a wall or partition, a capped nipple should be used. To close openings in cast-iron pipe, special plugs or stoppers must be used as they can be easily removed without jarring the pipe after the system is tested. A Testing Plug that is used for closing openings to cast-iron pip is held in place and made water tight by a rubber band under compression bearing against the inner surface of a pipe or fitting. The testing plug should be placed inside of the spigot end a of pipe or fitting and not in the hub, as the increased surface exposed to the pressure of water or air when placed in a hub increases the liability of the plug blowing out. These plugs are only suitable for testing systems where the head of water does not exceed 50 feet. Where plugs of this type are used, a stop cock c can be substituted for the cap on the end of the handle, and the system can be filled and emptied through the stop cock. When testing the drainage use the type of stopper that cannot be blown off under any pressure likely to be encountered in testing drainage systems. When applied to the spigot end of a pipe the stopper must be provided with a collar to hold the clamps. Stop cocks can be screwed to the capped outlets of these soil pipe plugs through which to fill and empty the system.

Laying Drainage System Pipes

Laying Drainage System Pipes

Posted By: Nyumba Imara Blog on 17th of October 2013

Drainage systems are a common encounter our everyday world of building and construction. Most often people think of drainage as a piping systems of underground structures used to convey liquids of one sort or another. To a layman, the concept of drainage system installation sounds as easy and straight forward as digging  a trench, laying the pipe in the trench and filling covering the trench. Inasmuch as this simplified perspective of pipeline construction may be appealing, it does not to address the engineering concepts that must be observed in any drainage system and the underground installation of a pipeline. Generally there are two objectives that must be achieved in any drainage system installation. The first is to provide an envelope of embedment to protect the pipe from mechanical damage that may be caused by impact or hard objects like cobbles and boulders in the soil and is second is to cushion and support the pipe against earth and live load pressures. Some pipes are designed carry more loads and require less support from the soil but when support is needed to protect the pipe embedment should be applied around the drainage pipes. The embedment material used must be well compacted so as to provide sufficient resistance to the weight that earth and live loads may impose on the pipes. The trench back-fill placed on top of the embedment material should also be compacted as compaction of trench back-fill immediately above the pipe facilitates the redistribution of some of the load away from the pipe and into the side-fill soil. Let’s now take a look at what the laying of a drainage system involves; Foundation In some soil condition it may be found that the trench bottom cannot provide a firm working platform for placement of the pipe bedding material. In such conditions foundation is required to provide a solid base on which the drainage pipes may rest undisturbed so as to maintain a constant flow of the liquids being conveyed through it. The pipe’s ability to support loads and resist deflection is determined by the quality of the embedment material and the quality of its placement. Laying of drainage foundation in the initial back-fill zone includes bedding, haunching, primary, and secondary zones. Bedding Bedding plays a crucial role in leveling out any irregularities and ensures uniform support along the length of the pipe. It also helps bringing the trench bottom to required grade. Haunching Hauching refers to back-fill under the lower half of the pipe. It helps in the distribution of the superimposed loadings. The nature of the haunching material and the quality of its placement are one of the most important factors in limiting the deformation of the drainage pipes. Primary Initial Back-fill This zone of back-fill provides the primary support against lateral pipe deformation. To ensure such support is available, this zone should extend from trench grade up to at least 75 percent of the pipe diameter. Under some conditions, such as when the pipe will be permanently below the ground water table, the primary initial back-fill should extend to at least 6 inches over the pipe. Secondary Initial Back-fill Secondary initial back-filling helps in the distribution of overhead loads and isolate the pipe from any adverse effects of the placement of the final back-fill. Final Back-fill Since the final back-fill is not an embedment material, its nature and quality of compaction has a lesser effect on the flexible pipe. However, arching and thus a load reduction on the pipe is promoted by a stiff back-fill. To avoid the possibility of impact or concentrated loadings on the pipe both during and after back-filling, the final back-fill should be free of large rocks, organic material and debris. The material and compaction requirements for the final back-fill should reflect sound construction practices and satisfy local ordinances and sidewalk, road building, or other applicable regulations.

Choosing Paint Colors for Different Rooms

Choosing Paint Colors for Different Rooms

Posted By: Designer Mjanja Blog on 7th of November 2013

Paint color is widely known to have quite a considerable effect on many elements in a room’s design scheme. The color applied on the walls, trim and ceiling can affect the atmosphere and mood while also reflecting the overall design style. Paint color can be used to highlight or emphasize architectural features or downplay them when you want a different effect. Having these factors on mind can help you choose the best colors even in challenging rooms with unusual design features such as living rooms with lofts. Room Size Emphasis The design of a high ceiling living room with is similar to that of a great room.  If you choose to emphasize this design feature, paint the room in very light colors such as shades of white or beige. White colors with cool undertones of blue or green will make the walls and ceiling appear to recede thus emphasizing the spaciousness. Pale shades of blue or green will have the same effect. White colors with warmer undertones of yellow or pink will lessen the effect slightly. Room Size Downplay If you aim to lessen the effect of a large space and create more of a warm, enclosed space, choose a darker and warmer color. Muted hues in golden yellow, orange or red will make the walls appear to advance. Dark brown will warm the room and make it appear smaller. Dark blue or green can make the room feel hollow. When aiming to downplay the room size care must be taken when it comes to choice of the color to apply as a dark wall color is harder to change should you decide that the color doesn’t look appealing anymore. If you use a darker color and decide to change it to a lighter one you will first have to cover the dark color with primer before painting the walls a lighter color. Try on a dark color by painting just one wall and observe the color effect under different lighting. If the color appears to be overwhelming on all the walls, keep the painted wall as an accent wall and choose a lighter shade in the same tone or a coordinating tone for the rest of the walls. Design Style Consider choosing the paint color that will enhance the design and style of the building. Most often go for bold and brighter colors when dealing with modern styles of architecture. For traditional home styles go for deep or dark color as they add some sense of sophistication to the home. Coastal, beach or cottage-style homes are often painted in light or pastel colors. Rustic and country homes tend to embrace natural colors with an emphasis on nature. Neutral color schemes are commonly found in contemporary homes and are quite satisfying to the sight when blended with accents rich in color and texture.

Interior Lighting Part 2

Interior Lighting Part 2

Posted By: Designer Mjanja Blog on 31st of October 2013

In this article we continue highlighting the common lighting mistakes to avoid and give some tips on how get you house lighting right;  Using incandescent or halogen sources without dimming While it is common for us to find ways of retrofitting lighting with more efficient, longer lived light sources than incandescent we should not forget that this type of lighting is still a viable and important part of lighting in a residence, provided it is dimmable. By dimming, we decrease energy and heat output, and we lengthen lamp life. Non- incorporation of Ambient, Task and Accent Lighting Lighting designers understand that all well-designed spaces incorporate different types of light. Ambient light is general lighting for walking around, conversing, and identifying objects. Task lighting provides higher, more concentrated lighting for tasks such as chopping vegetables, shaving, or reading. Accent light is used to highlight artwork or architectural features, such as the beautiful glass tile you’ve specified in the bath or the ceramic collection your client will showcase in open shelves in the kitchen. Combining all three types of light gives greater functionality, interest, and likelihood that you will have sufficient lighting. Neglecting to control different types of light separately For maximum efficiency and flexibility, each type of light should be controlled separately and any incandescent or halogen light or dimmable LED's should be dimmed. Controlling multiple sources can be achieved by the old school method of multiple light switches, but there are many more sophisticated ways to achieve control. From a simple programmable wall box system for single room control with preset scenes, to wireless controls that generate their own power and can be reprogrammed from a laptop. Controlling the lighting yields energy savings combined with the right amount and type of light for different times and uses. High Ceiling Recessed Down lights for Ambient light This results in a lot of wasted light and a very dark space. Light originating at high ceilings needs to have a focused tight beam spread with enough center beam candle power, such as that from a ceramic metal halide or high wattage halogen source. Better yet, using wall-mounted or pendant sources to reflect light off a ceiling surface often provides much better illumination than punching a lot of holes for recessed down lights. Decorating with light Decorating with light fixtures, or choosing fixtures based on how they look rather than their light output, performance and distribution often results in a waste of energy and less than optimal light output. For assistance with architectural light fixture choices, consider hiring a professional lighting designer who can transform your space through light, while providing adequate task lighting and often saving energy. On the Fundi Mjanja website, such professionals are listed under Interior Designers and can be found on the following link; http://www.fundimjanja.com/index.php?option=com_category&view=components&Itemid=122&cartId=33

Interior Lighting part 1

Interior Lighting

Posted By: Designer Mjanja Blog on 24th of October 2013

Interior designers are often called upon to give input about lighting in residential environments. In trying to tackle a lighting dilemma, many fixtures get specified in living areas, kitchens and baths that waste energy and do not get light where it is needed most. These ineffective specifications are often repeated as homeowners are unsure of lighting solutions and tricks of the trade. Sometimes knowing what to do can help make you look like a pro. This article highlights the common lighting mistakes to avoid and gives some tips on how to do it right.  Over doing Recessed Down lights This is one of the most common errors that lighting design professionals see. Builder spec versions of can lights are quite affordable and people often assume that laying them out in a regular grid gets light everywhere. Unfortunately, this is not so. The optics of inexpensive can lights often allow only slightly more than half the lumen output of the lamp to escape. In addition, can lights, unless they are adjustable or wall wash fixtures, typically don't put sufficient light on vertical surfaces, which is where the eye perceives light. With an array of cans, we might waste nearly half our watts and still have a space that feels like a cave because the walls are dark. Kitchen Task lights  There are many better ways to light the counter, and one of them is to use fluorescent or LED task lights under the upper cabinets. If your kitchen design lacks upper cabinets over some work surfaces, don't worry. This is a situation where wall-mounted or ceiling recessed adjustable fixtures with the right lamp make all the difference. Adding several low voltage halogen fixtures with a narrow flood beam distribution and focusing them on the task area will do the trick. Remember to choose your fluorescent or LED color temperature wisely. Down lights without Side lights Standing directly under a down light, without any light at the sides of the face, creates exaggerated and unflattering shadows. In the bathroom, using a down light over the sink is fine to accent the expensive polished nickel faucet you've specified, but it is insufficient for tasks like shaving, tweezing, and applying makeup. For this, we need light at the sides of the mirror at eye level to minimize shadows and provide even distribution. This can be achieved with sconces flanking the mirror.

Reducing Weight in Suspended Concrete Floors using Hollow Blocks

Reducing Weight in Suspended Concrete Floors using Hollow Blocks

Posted By: Fundi Mfalme Blog on 10th of October 2013

Suspended concrete floors are found in storeyed 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 making these kind of floors 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 after every nine hundred millimeters (blocks) row. 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 formwork to pave way for plaster finishes.

Clay Tile Roof Repair

Clay Tile Roof Repair

Posted By: Fundi Mfalme Blog on 17th of October 2013

A clay tile roof is often susceptible to leaks caused by various problems either with the tile itself or by the method of installation hence the method employed in the repair of a leak will often differ depending on the cause of the problem. More than any other roof type, the traditional tile roof is an architectural feature deserving of special attention because the texture, color, and play of light and shadow impart a distinctive character to a building that no other roof type can match. Yet tens of thousands of tile roofs have been lost in recent decades because of the ignorance or laziness of low-level roof repair contractors. So it is of paramount importance to have your tile roof fixed by a qualified and experienced roofer. Leaking in clay roof tiles may be due to several faults. Some leakage problems go beyond the roof clay tile being related to the other aspects of the roofing or installation methods. Some of the common problems that relate to leakage in clay tiles are: Defective or worn out waterproof membrane Collection of debris in the roof valley that cause water to accumulate on the valley Cracked tiles Broken tiles The defects that may result in a leaking clay tile roof can be dealt by a careful consideration of the following measures; Fixing a Membrane More than often the leakage may be as result of defective in the waterproof membrane. If such is the cause of the leakage then the waterproof membrane will need to be replaced. This is done by removing all the existing tiles and replacing the old membrane with a new one. Then the roof is re-tiled. This must be done by the help of a professional to avoid a re-occurrence of a similar problem in future. Removing the Debris It is a common occurrence for the roof valleys especially the closed ones to collect a lot of debris. More often than not, this can cause leaks in clay roof tiles. In order to remove the debris such that there is no more leakage, you will need to remove the tiles from the valley, clean out the area, and then reinstall the tile. You may also need to consider converting the closed roof valleys into open ones to avoid debris collection in the future. Fixing a Crack If you find that there are fine cracks in your tiles, you can repair the crack by applying a crack sealant to the tile to deal with the problem. When applying the crack sealant allow  it to spread over the entire tile and let it dry. Fixing Broken Tiles Tiles that are broken or have large cracks need to be replaced in order to fix the leak. For this, you will need to remove all damaged tiles. The removal must be carefully done to avoid causing damage to the good tiles next to the broken ones. If your roof is old, chances are your tiles have been fixed using mortar. If that is the case, place the new tiles and use the mortar to seal them in place. Metal Flashing In some cases the leakage in the roof might be as a result of failure of metal flashing. If the metal flashing is the source of the leakage then it's possible to lift a limited number of tiles, replace all flashing and re-lay the original tiles. During this process, you may also find some broken or cracked tiles. (An experienced roofer can tell by gentle tapping whether a tile retains its structural integrity or has hidden fissures.) Cracked or leaking tiles should be replaced at this time. Work on an existing tile roof must be done by an experienced roof tile contractor; an inexperienced contractor may break more tiles than he or she replaces.

Fixing a Tile Roof Underlay

Fixing a Tile Roof Underlay

Posted By: Fundi Mfalme Blog on 24th of October 2013

Roofing underlays are used underneath the final tile roof covers. They are fixed before laying roofing tiles or shingles so as to prevent any rain water from passing through to the ceiling as the tiles or shingle roof covers may allow water to seep through when broken.  Roofing underlays can be polythene or bituminous in nature or as it is common nowadays plain metal sheets or corrugated iron sheets. The placing of the felt or underlay should be done by a qualified carpenter and with due diligence as this will help to safeguard the ceiling and entire house from any roof leaks. For the roofing felt to function effectively care must be taken when laying it to ensure that it is free from any punctures as these are likely points that water may pass through to the ceiling of the house. When using polythene, it should be heavy gauge and preferably laid in two sheets. This is because the temperature in the roof space may rise thus leading to damages on the felt. The bituminous felt should preferably be the sand blasted type. This is able to take higher temperatures without breaking within the roof space. The felts should be laid smooth from the ridge to the eaves. This prevent them breaking after they become brittle during the cold season. Metal iron sheet has become the most preferred roof underlay in the recent years as it is more durable and reliable. In comparison to polythene underlays it is less susceptible to damage during installation thus preventing the likelihood of any leakages after installation. It is durable, wind- and fire-resistant and practically maintenance-free, but it must be installed properly by a qualified metal roof carpenter as its installation requires specialized skills. However, the options and installation process for metal underlay are largely the same as shingles or other roofing materials. When laying polythene roofing felt, ensure the surface is horizontal and level. The roof structure is first completed then polythene is laid using plastic straps. The straps are nailed on the purlins in a mesh pattern and they should be tight to prevent sagging under water weight.  After completion the polythene underlay is laid on top then the roof battens are nailed onto the purlins according to the tile specifications.  The laying of tiles is then done after testing for sagging or any leaks within the felt.

Installing a paved driveway

A home or an office driveway or walkway will always having a lasting impression on visitors. Block pavers can make the difference between an ordinary walkway and stunning curb appeal. Curb appeal will do wonders if you are trying to sell a house, it will force the potential home buyer to stop and take notice. 

When choosing a driveway or patio, there are many choices available. Concrete is so brittle and breaks so easily while asphalt is not at all pretty. Gravel is cheap, but needs replacing often and finding gravel in the lawn with your feet or the lawnmower can be uncomfortable and dangerous. One of the commonly used ways of beautifying the walkway, driveway or patio that will not disappoint is by use of paving blocks. They come in so many colors, designs and sizes and allowing the owner or contractor choices of patterns and edgings to make a driveway or patio a piece of art. Repairs, if necessary, require no more than picking up a broken paver and replacing it. There's no better material than pavers for your driveway or patio.

To avoid frustration and wasted time and ensure that your driveway turns out as beautifully as possible it's important to carefully follow the directions when installing the pavers;

Prepare the base

Mark the area and excavate it to a depth of 4 inches (100mm) for patios and sidewalks. If the area is being laid with paving blocks for the first time the topsoil has to be removed before final marking for excavation. In case the topsoil is large, you can rent a topsoil remover to lighten the work of removing it. Save the topsoil heap in one spot as it can become handy in future for landscaping purposes. Special care should be taken in case of cotton soil; all of it should be removed and disposed. Paving blocks should never be laid on unstable ground.

When working on an existing patio or driveway remove the existing one by use of a sledgehammer and pick axe to break up the old sidewalk. The work will be easier if you create gaps or holes in the pavement to allow you to break and pry up the pieces.

If you are paving a driveway, excavate at least 10 to 14 inches (250 – 350mm) so you can make a paver base of at least 8 to 12 inches (200 – 300mm) of road gravel, crushed rock or quarry chips. You can easily get the quarry chips or gravel for the paver base from local quarries.

Rake out and compact the base material

Compacting is the most important part of any paving project. Place enough gravel to a depth within 3 inches (75mm) below the finished grade of the pavers. Allow for a slight grade so water will not puddle in your driveway.  A well compacted base will always ensure that the driveway or patio withstands the pressure imposed on it by heavy loads.

Add sand to a depth of 2 inches (75mm) below final paver grade and screed to a smooth surface. This grade will allow for settling allowance during final compaction. Keep material smooth during installation.

Setting the Pavers on the Base

When you finally starting laying the paving blocks on the finished base, start with a straight edge or corner. Edging should rise just slightly above the walkway, so keep the sand about 2 inches below the top of the edging.  Use a string line to keep the pavers straight. If you are paving a large, wide area, begin at a center line and work toward each edge. This helps keep the pavers better aligned. Keep the pattern in alignment. Always place all full pavers before doing any edge cuts.

When you are finished setting all pavers in place, sprinkle sand over the entire surface and compact using a compactor plate.The compactor plate helps in vibrating and running sand into joints.  After compacting is done, fill edge joints with concrete if they are twenty five percent less than a full block.
Edges or road curb should be dry before laying any blocks as they could easily give way due to compaction. Once work is complete sweep off excess sand and debris Sweep off the excess sand. If you wish, you can apply a sealer to enhance the color and give it a wet look. Care should be taken in applying the sealer so that the paved block surface does not become slippery.

Building Cladding

Cladding is the application of one material over another to provide a skin or layer intended to control the infiltration of weather elements such as wind, rain extreme heat etc or for aesthetic purposes. Often time building cladding does not necessarily have to provide a waterproof condition but in some situations can be applied as a control element. Cladding as a control element may only serve to safely direct water or wind in order to control run-off of the same and prevent infiltration into the building structure.

As with all other exposed portions of the building enclosure (windows, roofs and balconies), regular review and maintenance of the cladding is important to ensure intended performance and appearance. Cladding is the first line of defense in a wall assembly. It is critical for protection of the more sensitive components of the wall assembly and the interior of the building. Proper maintenance of the cladding will reduce the likelihood of water penetration and preserve the appearance of the building. Wear and tear on cladding is expected since it is continually exposed to sun, rain, wind and temperature changes. In addition, cladding is subject to damage due to accidents, vandalism and excessive vegetation growth.

Cladding has become one of the most popular alternatives for renovating the exterior of existing buildings as it gives a building a new look and a new life.  Cladding benefits are greatest when dealing with high story buildings or buildings confined in a small site, where demolishing process is almost impossible and not feasible.

Benefits of Building Cladding

Aesthetics is a huge factor when dealing with wall cladding projects. Several solutions have become available that minimize system depth at the same time achieving the expected aesthetic. Some of the benefits that arise with the cladding process are:

• Prolonged service life of the structure

• Rise in revenue and value of the building (commercial buildings)

• Improved appearance and beauty of structure

• Improvement of thermal acoustic and natural daylight performance

• Protection of the structure from water penetration and improvement air tightness

• Lowers maintenance costs and allows upgrading of building services