Source: https://www.quantsurv.com/resources/glossary/cdp Content format: Markdown version of the public page. Content reviewed: 2026-09-30 # CDP (Contractor's Designed Portion): definition and example The part of a JCT building contract that the contractor designs. By [Jack Butler-Kettle]() ยท Updated 30 September 2026 Guidance for England and Wales. Check the contract, amendments and facts that apply to your job. ## What it means in practice Read this alongside [JCT Design and Build Contract 2016: Simply Fair](). A Contractor's Designed Portion identifies design work allocated to the contractor within the relevant JCT arrangement. A subcontractor's duties depend on what its own appointment passes down. Design development, coordination and responsibility for specified performance may involve different obligations. Compare the design scope with qualifications and insurance requirements. A [pre-signing contract review]() can highlight obligations needing agreement before design starts. ## Worked example ### The facts A specialist is asked to design a staircase connection while the main structure is designed by others. ### What happens 1. It records the design interfaces and the information it will rely on. 2. It checks whether its subcontract requires connection design only or a wider performance obligation. ### What this shows The scope of responsibility follows the agreed documents, rather than the CDP label alone. ## Sources 1. [JCT Design and Build Contract 2016: Simply Fair (12 July 2017)](). The Joint Contracts Tribunal.