In previous articles we looked at what a specification was and options of how to create one. In this article, we talk about the approaches to putting a specification together and what to consider.
The Subtractive Approach
A subtractive approach is particularly suited to preparing specifications based on a requirement to comply, or to confirm compliance with, a prescriptive code or universal standard. In this approach, you delete what doesn’t apply to the project you are designing from a series of standard work sections.
Unfortunately, most projects will also require the addition of project-specific data and/or instruction which makes the subtractive approach impractical.
The Additive Approach
The additive approach allows the specifier to mix and match clauses from the total specification database to accurately reflect the project in hand. The additive approach sees the specifier adding project clauses and selections.
When using this approach, the specifier is able to add project-specific selections and project-based descriptive clauses. This enhances the ability to produce a truly customised specification.
Mixed Approach: Recommended
While a truly additive system may seem to offer advantages in terms of producing a truly customised end product with minimum effort, this is unlikely to be practical. The best and most efficient approach is to mix additive and subtractive by using a master specification system.
Master specification systems, such as Masterspec – allow specifiers to choose the content they require and customise the specification using a mixture of subtractive and additive techniques. Based on the master specification system, this is a quick process that allows specifiers to be left with a project specific document that is consistent with the latest building codes and standards.
Why not use a standard specification? Even for those designers involved in one type of project, a standard specification will not automatically provide current building control mechanisms. Significant differences will also arise from one project to another, due to site constraints, or individual client preferences.
Specifications need to be in-depth and very specific. Leaving your design up for interpretation may result in your original design changing dramatically. For example, instead of a general statement of “concrete”, your specifications would define the depth of the concrete, where it is placed and perhaps a different supplier than you would prefer.
A specification should include the following:
- Completed schedules for windows, finishes and linings.
- Information about specific products and materials required for compliance
- How materials should be fixed and placed
- The work that needs to be carried out
- Acceptable standards for each trade or aspect of the construction
Subtractive and additive approaches are used when building a specification within Masterspec. New Zealand’s largest online specification library allows you to manage your risk, obtain up to date content and minimise your time writing specifications. Specification writing is imperative for every design and can be very time-consuming. Efficiently build specifications with pre-populated templates and information with Masterspec. The online specification system also allows you to update the specification information if there are changes throughout their project life. Specifications allow professionals to keep a record of their design intent in the unlikely case of a dispute.
Not sure if a specification system is right for you? Try Masterspec's 30 day free trial today.