This article, by the NBS technical team, is aimed specifically at using NBS content. For NBS software support, start by checking out the support area of our site.

The nature of master specification systems

Master specification systems such as NBS have to cover a wide range of specification needs, and inevitably won' t serve everyone' s (or anyone' s) needs perfectly. You will always need to delete material, add material, edit material, and select or author values. As general purpose tools, they tend to cover the more common constructions well, and the less common constructions less well. Their content assumes a certain level of understanding of building technology and contractual, specification and editorial principles – not too much, but not too little either.

The specification text we offer in NBS is best regarded as default, not gospel. If it doesn' t suit, please feel free to alter it. It can often be adapted for technologies not explicitly covered in NBS. For example, if you want to specify a paving system not covered in NBS, then take the most pertinent system clause we do have and adapt it to suit.

The right version of NBS

At work section level, NBS is an additive specification system – you start with an empty document and add the sections you want from the NBS library. At clause level, NBS is a subtractive specification system – when you open a work section a full set of clauses appears. You are expected to exclude those that are not required (NBS Scheduler, on the other hand, is an additive system – you start with a blank page for the schedule of work).

To save you time we have produced, in NBS Building, three versions of most work sections – S (Standard version), I (Intermediate version) and M (Minor works version). Choose the one that will involve you in the best balance between deleting clauses and adding clauses of your own. For NBS Engineering Services, there are two levels to choose from – the full sections, or the small-works self-contained 90s (e.g. V90, V91). For NBS Landscape there is just one level offered, which is a mix of S, I and M work sections. NBS Scheduler also has just one level, with content derived mainly from I work sections. To see all this in more detail, have a look at the Scope & Contents pages for each product, e.g., NBS Building.

Timing and maintenance

The key to producing good project specifications is to allow sufficient time. Using NBS will be faster than starting from scratch, but still takes time. In particular, the specification and the production drawings should be developed in parallel, with those responsible for each communicating with each other about annotation and cross referencing (for which only selected clause numbers and titles may be needed, in line with the principles of Coordinated Project Information), and technical choices (for which clause text will be needed).

Time spent on project specifications can be reduced if time is invested in an office master specification. It can also be reduced if an existing specification for a similar project is re-used. NBS software supports both ways of working. However, there are dangers here. Office masters must be properly maintained, but often are not. Project specifications must be checked for currency and relevance, but often are not.

NBS itself must also be maintained, ideally as the updates are received rather than waiting until you are about to prepare a project specification. We help you keep up to date by publishing updates every 4 months as well interim online updates. At each update we tell you what has changed and why.

For NBS Building, NBS Landscape and NBS Engineering Services we also provide a software tool called Validate to manage the updating process. This can be used to maintain the original NBS master, and office masters and project specifications linked to the original NBS. For new projects simply select sections from the current NBS library. If an update occurs after a project specification has been started you will need to assess the level of change against the extent of the completed specification. If a section has been issued early or for a pre-tender, and an important update has occurred, consider contractual means, e.g. an architect' s instruction, to update the requirements.

Available guidance

You should always give yourself enough time to check NBS guidance. Guidance is helpful in selecting clauses and completing them. For NBS Building, NBS Landscape and NBS Engineering Services, as well as the Clause guidance attached to individual clauses, guidance also exists at section level, where it is called General guidance. This is well worth a visit but is sometimes overlooked, especially by users of software versions of NBS. Clause guidance may point to it. General guidance is often useful at design stage, i.e. before production information is usually started.

Guidance in the NBS software also links to a wide range of external documents such as British Standards, Building Regulations and industry websites. Again, you should allow time to review this material.

Preliminaries and General Conditions

Preliminaries clauses are used to describe things which relate to the whole project, and which are generally the administrative responsibility of the main contractor – things like site access, working times, what contract is used and how to deal with other information. NBS Preliminaries sections also contain material that's relevant to those working to the technical work sections (e.g. subcontractors), and is complementary to and synchronized with them. The two should be read together to allow for proper coordination.

If you are not involved in compiling the project Preliminaries, you should at least be familiar with them, and with the general conditions of contract being used. If you are expecting to administer and supervise the works on site, you will need to know precisely what is included. Ask to be sent copies. If you believe something is missing, then let the responsible party know. Do not simply add the missing material to your technical sections without telling anyone – you may end up with a serious conflict!

Finding stuff

The NBS Building, NBS Landscape and NBS Engineering Services software has a search tool – the magnifying glass icon in the Guidance panel toolbar. This will search the guidance (but not the specification text), and is useful for finding items tucked away in unexpected places. NBS Scheduler has a similar guidance search tool, but also allows content searching in the library panel.

NBS Building users should bear in mind that many engineering services, such as escalators and passenger lifts, are only covered in NBS Engineering Services, and that some small-works engineering services material is held in NBS Building Intermediate or Minor works versions only, and won' t be found in Standard version. Conversely, NBS Engineering Services includes some simple fabric content, e.g. in the P group, but more sophisticated content is held in NBS Building.

If in doubt, leave it out

NBS is intended to be suitable for a wide range of projects, from the unsophisticated to the sophisticated. In any given specification, a significant percentage of NBS clauses will not be needed, and should be omitted. The guidance should help you work out what should stay and what should go, but a good rule of thumb is ' if in doubt, leave it out' . If you don' t know what the clause is about, then you probably don' t need it, and you won' t be able to answer questions on it or enforce it. Also, the project specification is not meant to cover ' what if' scenarios – variation orders or instructions issued by the CA are the right place to deal with changes of mind, or unwanted eventualities such as non-compliance.

Editing NBS Building, NBS Landscape and NBS Engineering Services clauses

As well as omitting unwanted clauses – easy in NBS – you will also want to edit some items (aka bullets or subclauses) within clauses. Each clause in NBS software is protected against accidental editing to preserve its integrity. To edit NBS clauses (i.e. to delete items, alter words, or add new items) they must first be copied (in the NBS software, hit the return key three times). The copies are fully editable.

To identify copied clauses, or DIY clauses (see below), some offices add standard suffixes, e.g. if F10/310 is the original NBS clause, F10/310A might indicate the office master version, and F10/310B etc. project-specific versions. Others use sequential numbering for copied clauses, e.g. F10/311 etc.

Generic vs proprietary product specification

Generic product specifications don't name the manufacturer or product reference, describing the product in open terms instead, whereas proprietary product specifications do. NBS product clauses support both generic and proprietary specification but need to be edited to support one or the other. For generic specification, under Manufacturer/ Product reference insert either Contractor's choice or Submit proposals. This is straightforward.

For proprietary specification, a suitable NBS Plus clause can be selected if available. In NBS Engineering Services this involves a simple substitution of a branded clause for a generic one. In NBS Building, NBS Landscape and NBS Scheduler this will often involve editing of the generic specification clause, since some of its content will still be needed. For example, if selecting a brick clause from NBS Plus, the corresponding generic clause must be copied, and the brick product items deleted, whilst retaining the text on mortars, execution and so on.

If an NBS Plus clause is not available, copy the generic clause, insert the manufacturer' s name and product reference code, and then edit the rest of the clause, deleting items that are covered by the product reference, but retaining and completing those that are not, such as Colour.


You will, from time to time, need to add sections, subsections and clauses to NBS. The general rule is to follow the construction sequence, e.g. design precedes construction, excavation precedes in situ concrete. When adding sections, have a look at the Common Arrangement of Work Sections (CAWS) externallink, published by CPIC, to see where they might go. The Standard Method of Measurement for Building Works (SMM7) externallink and many price books also use this classification system.

Finally, if you do have any queries about the NBS software or content, then please get in touch – give us a call on 0845 456 9594, or email us at But, for content queries, have a look at the FAQs first, under Ask NBS in the Support area. We may have answered your question already!