THE BUILDING DESIGNER - Leading Construction and Building Group

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THE BUILDING DESIGNER

The majority of prospective homeowners are under the misconception that employing professionals is only for the wealthy. This could not be further from the truth, and yet, vast sums of money continue to be spent on badly designed homes.

Badly designed buildings can create astronomical hidden costs and become poor investments. By not utilising the skills of a trained professional from the beginning, a dream home will quickly turn into a nightmare. For example, a roof structure makes up 20% of the building cost and if inexpertly designed, could double in cost. The functionality and aesthetics of the building must be taken into consideration, as well as budget constraints. In selecting a designer, it is of utmost importance to establish a comfortable working relationship, ensuring that the design of a home is a team effort. Before selecting a designer, one should view completed projects and speak to various clients for feedback.

The basic tasks of the building designer can be broken down as follows:

PREPARATION

Upon taking an initial brief, the building designer will produce a set of sketch plans, which should conform to the following criteria:

  • The house must be aesthetically pleasing as well as practical to live in
  • The design must fit comfortably on the proposed stand
  • The design must be positioned in such a way that it benefits from the elements that surround it rather than be hindered by them
  • The budget must be strictly adhered to.

Budgeting is an extremely important step to the final outcome and success of a project. Over-designing at the onset can be extremely disappointing when quotes or the bill of quantities state that the project is wildly out of reach of the proposed budget. This ultimately leads to an additional expense and time delays whilst the designer redraws the project. Most project costs can be established as early as sketch level allowing the client to elaborate on or reduce the design.

WORKING DRAWINGS

Once a design has been settled upon, the designer may now commence with full working drawings. At this stage, the client will assist the designer by specifying what types of finishes will be required and these will be included on the working drawings. Itemising even the smallest and most insignificant item will reduce the margin of error when construction begins. The designer will collate this information into a finishing schedule, and where specific items cannot be finalised, a reasonable budget for these items will be allowed. Final working drawings are extremely detailed and show elevations of the building from the north, south, east and west. Drawings will include sections and roof layouts, as well as a detailed floor plan with electrical and plumbing layouts. Research shows that less than 30% of the resources required are on the average drawing. A professional should provide a comprehensive set of working drawings to ensure that the contractor does not misinterpret plans.

BUILDING COSTS RELATED TO DESIGN

A badly designed building will generally cost more money than initially envisaged. If design elements are not thought through carefully during the design process, the building will almost certainly be faced with unforeseen problems. These problems cost money. Square metre building rates are the biggest myth in the building industry. No two structures can possibly be identical; it is therefore obvious that a general square metre building rate cannot be assumed. There are examples of homes equivalent in size that vary in cost by two hundred percent. There are four major areas in construction that one must take into account when considering building costs. These are listed below.

SITE ELEMENTS

Various site conditions may affect the cost of building. The first consideration is always the slope or gradient of the site. Visually, a site always seems more level than it actually is. A variance of only one metre across a two hundred square metre house (assuming a length of 20 metres) would increase the brick quantity by approximately ten thousand bricks. If one considers the price of the bricks, mortar and labour, this could amount to nearly R7,000-00. In terms of building regulations, the height of the foundation brickwork may also require that the thickness of the wall be increased; amounting to more cost. Sites with very steep gradients usually require retaining walls, which are extremely expensive, particularly when structural reinforced concrete is required. Retaining walls also require vertical damp-proofing and agricultural drains.

Natural obstructions such as trees and rocks cost money in terms of removal or incorporating them into the design. The roots of a large tree may require excavation of up to three cubic metres. Rocks are usually a lot bigger than they seem on the surface. The perception about building a house on a rock does not usually work in practice. If a structure is bridged across any rock, an engineer will be required to design specific foundations.

Unexpected obstructions can also cost money if not identified during design. These obstructions would include electrical poles, fire hydrants, storm water drains and trees planted on the pavement. An electrical pole blocking a proposed driveway could be a costly exercise to remedy.

FOUNDATION ELEMENTS

As mentioned above, the gradient of a building site will affect the cost of the foundations. There are however, other factors that may influence costs. Poor soil conditions may require engineered foundations. A 250 square metre home built in Gauteng in 1997 incurred an additional cost of R70,000-00 due to soil conditions and the necessity to use concrete piling. It is good practice to have the soil conditions tested by a geotechnical engineer before design and, if possible, before even buying the stand. Complicated structures with split-levels or columns will always increase the foundation cost, even if built on a level site.

SUPERSTRUCTURE ELEMENTS

These elements are contained in the structure between the foundation and roof, the major element being the walls. There are many elements that will influence the cost of the superstructure. Unlike the foundations there are doors, windows and types of materials utilised that present numerous variables when considering costs.

SINGLE STOREY VS DOUBLE STOREY

There are significant cost differences for a single storey dwelling and a double storey dwelling.


  

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