It is absolutely vital to create a comprehensive specification for any building project; one cannot use general notes and provisions for accurate costing purposes. As the word suggests, a specification contains specific information. For example, a door is not simply a door – it has a frame and furniture (hinges, handles, locksets) and can be made from a number of different materials.
To estimate the cost of a project without a specification is impossible and to enter into a contract without one is very short sighted. Too many building contracts are entered into with vague information, resulting in a myriad of problems; the most common being significant cost overruns. The specification should form an integral part of the building contract. It is also important to note that there is no such thing as a standard specification as no two structures are alike or use the same materials. In some countries construction specifications for building work are written using specification systems purposely designed describing activities, products and other requirements into a standard order; with each activity or product designated a special code. For example in the United States and Canada the MasterFormat™ system is used and in the UK the RIBA system is used.
Another South African product that has facilitated with specifications to the residential building industry for over 21 years has been the Buildaid Building & Pricing Guide1. This Annual publication forms the basis of a building specification and follows a standard sequence for identifying and referring to the required construction information needed for a well prepared specification; with each section and sub-section providing important information on a number of products, trades and/or activities.
The following categories act as a guide for a well prepared specification and where required, the sub-groups would need to be described in detail for a specification to be complete.
Window and door positions and heights (the height of a door is always measured from the floor level, which is conventionally 2125mm to lintel height. A window is measured down from lintel height, so if the window is 1200mm in height, then 1200mm will be measured down from 2125 which is the lintel height). See Figure 5.3.
Note: The coordination between the kitchen contractor and plumber is essential.
See Figure 5.4 for and example of an electrical layout
Note: A sample panel should always be used on site to ensure consistency and used as a reference for quality and texture.
Note: When allowing an amount for tiling per m2 the quantity to be laid must be specified.
Note: Finished floor levels need to be specified to accommodate different flooring thicknesses.
Note: The above list describes the most common items and is non-exhaustive and is offered as a guide only and the publishers cannot be held responsible for any omissions.
Extract from the National Building Regulations (NBR) – SANS 10400 Part A
A13 Building Materials and Tests
(1) (a) Material used in the erection of a building shall be suitable for the purpose for which it is to be used.
(b) All timber used in the erection of a building shall be treated against termite and wood borer attack and fungal decay in accordance with the requirements of SANS 10005 and shall bear the product certification mark of a body certified by the South African National Accreditation System.
(c) The requirements of subregulation, (1)(a) shall be deemed to be satisfied if such material complies with and is incorporated into buildings in accordance with the requirements of SANS 10400.
(2) The local authority may test or cause to be tested any material or component used or to be used in the erection of any building in order to determine whether such material or component complies with the requirements of these Regulations, and any officer of such local authority duly authorized for that purpose may, at any time after consultation with the person erecting such building, remove from the building site concerned so much of such material or component as is reasonably necessary to serve as a sample for the purpose of such test: Provided that the authorized officer may not exercise his powers in such a way that work of such erection is stopped when such material or component is being so removed and tested.
(3) If any material or component tested in terms of subregulation (2) does not comply with these Regulations the local authority may serve a notice on such person, stating the respects in which such material or component does not comply and prohibiting such person from making further use of such material or component for the purpose for which it was or is to be used in the erection of such building.
(4) Except in the case where in such notice the local authority permits the use of such material or component in the erection of such building for some different purpose permitted in terms of these Regulations, such person shall forthwith on receipt of such notice remove such material or component from such building or building site or from both, as the case may be.
(5) If any material or component contemplated in subregulation (2) is tested and has failed to comply with these Regulations the local authority may recover the cost of such test from the owner of the building concerned.
(6) Where the owner of any building desires to use for a particular purpose any material or component which is not permitted or prescribed by these Regulations to be used for that purpose, and he satisfies the local authority that such material or component is at least as suitable for that purpose as the material or component permitted or prescribed to be used by these Regulations, then the local authority shall permit the use of such material or component for the purpose concerned.