- additional information on the client's requirements to that provided at the inception stage (stage A);
- detailed information on the site:
- information from third parties who may be involved with the proposed building;
- information on costs.
One of the earliest tasks for the architect is to carry out the site investigation to identify key construction and design constraints. These constraints may be physical, financial or legal.
Design Constraints
Site Constraints
An initial site investigation report consisting of a graphical and written report will become a source of reference when compiling the feasibility report for the client. Hard data about the site is essential: this involves a site survey showing boundaries, areas, and dimensions to enable a site plot to be drawn to scale. This will also allow the size of the site to be calculated. Any other necessary details will be collected from the site.
- The architect must specify the position of utility services, whether overhead or underground, and their size and depth.
- Existing buildings need to be measured on the site: the surrounding built environment, any adjoining buildings, the streetscape, the roofscape and the natural environment must be recorded.
- Ground levels must be obtained and bench mark location recorded. Soil investigation may take the form of a field surveyor a desktop survey using geological maps.
- Infrastructure details, road and rail links, access.
The collected information and plans will form the basis for the feasibility report. ldeas about the viability of the project will often depend on the predicted costs.
At the conclusion of all his investigations and enquiries the architect will then be able to report back to the client to state whether or not it is a feasible proposition to build a building of the type the client requires on the site in question. Sometimes the answer will be a straight 'yes'. At other times the architect will report that is is possible to build a building to meet the client's needs but that it would have to be in a different form from that originally envisaged.
In any event the architect will also include a preliminary cost appraisal to check on the feasibility of providing the type of building the client wants for the amount of money he has to spend. Often cost studies of alternative solutions to the one originally discussed with the client may be prepared if this is thought to be in the client's interest.
The form of the feasibility report will depend on the size, type, and importance of the project. On a very small job it may consist of little more than a long letter. On a large important job it will include drawings, perhaps a model, details of people involved, information on the site, design constraints, cost appraisals, the anticipated programme, together with schedules of the accommodation and room areas.
To conclude on how the site can restrict construction project, the following questions should be considered to determine the mass and building form for the final design:
- Does the building make full use of the sites natural potential?
- Does the building enhance the built environment?
Since the work of the architect is very visible, these questions must be answered and analysed.
Access road levels and the site level will determine the position of the site entrance and internal road layouts. The soil investigation and orientation of the site will also effect the site access and the mass of the building.
Cost Constraints
As the cost of any job is so important, particularly to the client, approximate estimates are expected to be provided at the various pre-contract stages of the project.
The architect will remind his client that, until the detailed drawings have been prepared and priced, the estimate can of necessity only be approximate. Nevertheless, if the tender price is dramatically more than the first approximate estimate the client is likely to lose confidence in the architect and may even consider abandoning the project.
There are various types of approximate estimates and some of the more common ones are listed below.
Cost per unit of accommodation - Such costs are, for example, the price per bed for a hospital: per scholar for a school per seat for a church, theatre, or cinema: or per room for a block of flats. These unit costs provide an almost immediate method of putting a 'price tag' on a larger building. However, unless the figures are based on similar buildings they can only be taken as very approximate. To produce the approximate cost using this method, all that is required is for the client to state how many beds, scholars, seats, or rooms are needed, so that the architect or quantity surveyor, using a unit cost derived from previous, similar jobs can prepare an estimate by making a simple calculation.
Cost per square metre of floor area - This is a quick and easily adjustable method but it takes no account of heights, complexity, or plan shape of the building. Again, with this method an approximate cost can be produced without the need for any drawings. The client will have to supply a schedule of room areas to which the architect will add areas the client may have omitted, such as circulation spaces, toilets, etc. This will give an overall floor area, which can be multiplied by a price per square metre, derived from previous jobs. However, if the project is sufficiently advanced for sketch plans to have been prepared, the floor area, and hence the estimate, can be calculated with greater accuracy.
Cost per metre cubed of building - This is also a fairly quick method, but as it is generally used to produce an overall figure for the volume of the building it takes no account of the different room heights and uses within different parts of the building. Again, it is theoretically possible to produce an estimate before any drawings have been prepared, by calculating the total floor area, as described above and then multiplying it by an assumed average height, to arrive at the cubic capacity of the building. However, in practice this method is more likely to be used when plans and sections are both available, so that the cubic capacity can be calculated with a greater degree of accuracy.
Cost per element of building - When information on elements such as floors, walls, roof, ete. are available this method provides a more accurate estimate but takes longer to prepare, and sketch plans, elevations, and sections are required. Each element, including finishes, is priced according to a unit rate per square metre.
In addition to the above methods, at the later stages of the design process the quantity surveyor may take off approximate quantities to arrive at a more accurate estimate.
Apart from the cost acting as building constraint, there are also legal constraints to be considered.
Legal Constraints
There are two main groups of laws: common law, which follows custom and precedent, and legislative law, which is made by Parliament.
The law of property and land may influence the building design. Boundaries and casement may seriously restrict development; for instance, the local council may have right of access to lay drains under the land, and this easement can be used by the council to restrict the buildings layout or positioning. The restriction may be that a building cannot be erected within three metres of the public sewer.
The Town and Country Planning Acts have given the local authorities considerable powers to regulate the development of the built environment within the council boundaries. A structure plan, prepared by the county council, is available for developers, explaining the county council's strategy for development, and zoning of different areas for different purposes, which will include Green Belt land.
These development plans are produced after consul ration with interested parties. The district council, on the basis of the larger structure plan, will prepare the local plan. Development control may introduce further constraints regarding the density of activity permitted in the zoned area; for example, the density of housing development could be stipulated as a maximum number of dwellings per hectare. Other constraints limit the size of a building or the number of stories.
Areas of outstanding beauty or special scientific interest can be designated conservation areas. If development is allowed in a conservation area there will be stringent rules limiting the type, mass and the use of materials. It is not only the built environment that is subject to planning controls, but also the natural environment. Planning authorities have the power to designate tree preservation orders, affectionately known as TPOs.
Building regulations are concerned with the construction of buildings, rather than their appearance. They are intended to ensure that the design and construction will be such as to ensure public health and safety. These also act as a considerable constraint on the designer. There are two ways of complying with the regulations. The common method is to follow the means for meeting requirements of the regulations described in the set of approved documents. The alternative is to devise your own solution for meeting the requirements.
Health and safety guidelines come under statute law and are a major factor on projects in this day and age. Every site has to comply with strict guidelines put into place and inspected by the HSE (Health and Safety Executive). The HSE has the power to enter any building in the UK and can close down a project instantly. The health and safety plan/policy needs to be designed by a competent person at the design stage to ensure every possible action has been taken to enforce health and safety measures.
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