SITE WORKS

Choice of a site

There are a number of factors that should be considered when selecting a building site and these include the following

• The cost of the land where the site is located.
• The climate of the area.
• The aspect of the site; which helps to determine the amount of sunlight received on the various elevations of the building that in turn helps in the planning and location of the habitable rooms.
• The elevation of the site is also important since an elevated site is preferable due to its being drier and easier to drain as compared to the low-lying ones that are likely to be cold and damp.
• The prospect of the site. The site should be able to command a pleasant view and the adjoining land uses should be compatible.
• Availability of facilities. The site should ideally have access to schools, shops, parks, sports facilities, swimming pools, community centers and good public transport facilities.
• The site should have access to adequate services like electricity, water mains and sewers.
• The site subsoil‟s should merit special consideration because of their effect on the building work especially when it comes to choice of a foundation.
• Site contamination should be taken into consideration. One should avoid former industrial sites that could involve expensive site works to remove potential hazards.
• The water table of the site should be known. It‟s important that the building is erected well above the highest ground water level.
• Subsidence of the site especially in mining areas should also be taken into consideration.

Site investigations

All potential building sites need to be investigated to determine their suitability for building and the nature and context of preliminary work that will be needed.

During site investigation particular attention is given to the following;

• Nature of the soil and its probable load-bearing capacity which is usually done by means of trial holes or borings since there may be variations over the site.
• The level of the water table should also be established since a high water table may necessitate subsoil drainage and could cause flooding in winter.
• Ordnance survey maps, which could show the presence of disused mines or former ponds.
• The position and size of main services like sewers should be determined and it‟s advisable to take a framework of levels over the site so as to ease the draining of the site.
• The environment of the site should also be taken into account. This includes the mature trees on the site, which ought to be retained, or which are even subject to tree preservation orders or the site being located within a conservation area.
• Investigations should also include approaching local planning authorities to ascertain whether there are any special or significant restrictions that could adversely affect the development of the site, and the position of the building line or base line.

Site clearing

This is the demolition of existing buildings, the grubbing out of bushes and trees and the removal of soils to reduce levels on the site prior to construction.

Site clearing is important because it rids the site of any obstruction to the process of setting-out. The method chosen for the carrying out site clearing (whether mechanical or manual) is determined by overall economics.

Demolition

This is the partial or complete removal of a structure. Before demolition a series of steps have to be taken and these are as follows.

• Remove carefully all saleable items such as copper, lead, steel fittings, domestic fittings, windows, doors and frames.
• Examine condition and thickness of walls to be demolished and those to be retained.
• Check for the relationship as well as the condition of adjoining properties that may be affected by the demolition.
• Check on the nature of support to balconies, heavy cornices and stairs.
• Check whether the demolition will cause unbalanced thrusts to occur in the roof and framed structures.
• Check whether demolition will extend to public footpath or beyond boundary of site.
• The services to the structure should be sealed off, protected or removed and the service providers should be notified.
• All flammable or explosive materials such as oil drums and gas cylinders should be removed before demolition commences.
• Adequate insurance should be taken out by the contractor to cover all claims from workmen, any third party and claims for loss or damage to property including roads, pavings and services.
• Local authorities have to be notified.

There are four factors that determine the method of demolition to be used and these are:

• Type of structure. Whether the structure is storied, framed structure, reinforced concrete, chimney etc.
• Type of construction. Whether it‟s a masonry wall, concrete or of structural steel
• Location of site. Whether the site in the middle of a busy town or a less populated
•  The type of demolition. Whether the structure needs a complete or partial demolition.