For a relatively simple project such as a small extension, the specification documents might only consist of a set of the approved plans and Building Regulations drawings together with the approval notices and conditions, plus information provided by you explaining what you want in terms of lighting, power points, fitted furniture, kitchen and bathroom fittings, floor finishes, etc, including brand and product names. You must also include details of any work you will be handling yourself on a DIY basis, or which you plan to subcontract directly, any materials you plan to supply, and any other special requirements.
A smaller contractor may be willing to prepare a quote on this basis and to make allowances for any ‘grey areas’ where there is insufficient detail for them to provide an accurate price. These allowances are known as either Provisional Sums or Prime Cost Sums. A contract for this sort of project is available for free from The Federation of Master Builders but any contract you use, formal or informal, should describe the works both ‘specified and implied’, to oblige the contractor to take into account all works necessary in order for the project to be completed.
Medium and Large Projects
For a larger and more complex project such as a major extension, or a new house, it is always worth having a full specification document written out by the project designer. This is a written specification that supplements the notes on the drawings and is likely to run into dozens of pages, depending on the extent of the works. It will typically include a description of the materials, technical standards and techniques that are to be used for each aspect of the build.
In addition to the drawings prepared for the planning application and for the Building Regulations and copies of the approval notices and conditions, it will be necessary to produce and submit detailed larger-scale working drawings of any unusual or individual details that you want the builder to price for.
A covering letter may also indicate the basis on which tenders are invited, including the format the quotes are to take. A standard format is to show a bill of quantities, with each aspect of the work shown individually, with a breakdown of labour, materials, plant hire, and project management charges — the mark-up applied for project management. It may also indicate how allowances such as Provisional Sums and Prime Cost Sums should be treated, to make it easier to calculate actual costs later. Having a common format creates transparency and enables different quotes to be compared on a like-for-like basis.
It is also necessary to indicate when the works are to be commenced and completed, working hours and days, and what form of contract is to be used. There are several standard contracts available, including the range of JCT Contracts (Joint Contracts Tribunal) that are the industry standard.
If you are retaining your architect or another professional to administer the contract, then the ‘HO/C Building contract and consultancy agreement for a home owner/occupier’ contract is the one to go for. If you are not using an architect or other professional to administer the contract, the most suitable contract is the ‘HO/B Building contract for a home owner/occupier who has not appointed a consultant to oversee the work’.
Most standard contracts include a retention clause, and some also choose to include penalty clauses for late completion and incentive clauses for early completion.
The tender documents must also make clear who is responsible for preliminary costs, such as site access, security, storage, WC facilities, rest facilities, provision of water and power, site insurance, warranty cover, etc.
Finally, the documents must make it clear if you plan to subcontract any of the work directly to ‘nominated subcontractors’ or to handle any work on a DIY basis. The contract needs to identify who is to be responsible for this work should there be any defects or delays, and how the implications of this in terms of delays and additional costs are to be dealt with.