Construction Cost Planning for Extensions, Renovations & Developments
Accurate, independent cost plans that give homeowners, contractors, architects and developers clarity from the very start of a project.
Thomas Callum Associates provide detailed Construction Cost Plans for projects across London and the South East. Whether you’re planning an extension, refurbishment, basement conversion or full development, our cost plans give you a clear, realistic understanding of your project budget before work begins.
We help clients make informed decisions, avoid cost overruns and progress through design stages with confidence.
Clear, Accurate Cost Plans from Day One
A well‑prepared cost plan is essential for controlling your project budget. Our cost planning service provides a structured breakdown of expected costs, allowing you to understand financial implications, assess design options and ensure your project remains financially viable as it develops.
What Our Cost Planning Service Includes
Feasibility Cost Plans
Early‑stage cost advice to help you understand whether your project is financially viable.
- Initial budget guidance
- High‑level cost breakdowns
- Options analysis
RIBA Stage Cost Planning
Cost plans aligned with RIBA stages to support architects and clients throughout design development.
- Stage 2 concept cost plans
- Stage 3 developed design cost plans
- Stage 4 technical design cost checks
Detailed Cost Breakdown
Comprehensive cost plans covering all elements of the project.
- Substructure
- Superstructure
- Finishes
- MEP
- External works
- Preliminaries
- Contingencies
Material & Specification Analysis
Clear cost comparisons for different materials, finishes and specifications to support design decisions.
Value Engineering Options
Cost‑saving alternatives that maintain quality while reducing expenditure.
Budget Monitoring Through Design Changes
Updated cost plans as drawings evolve, ensuring your project remains aligned with your financial expectations.
Who Our Cost Planning Services Support
Homeowners
Clear cost plans for extensions, renovations and basement conversions, helping you understand realistic budgets before approaching contractors.
Architects
Reliable cost advice at RIBA stages, supporting design development and client budget management.
Contractors
Cost plans that help contractors understand project scope and anticipate likely budget expectations before tendering.
Interior Designers
Fit‑out cost plans and FF&E cost guidance for high‑end residential and commercial projects.
Developers
Feasibility cost plans, budget setting and value engineering for residential and commercial developments.
Why Choose Thomas Callum Associates?
Accurate & Transparent
Our cost plans are detailed, realistic and based on current market rates.
Aligned with RIBA Stages
We support architects and clients throughout the design process.
London & South East Specialists
We understand regional contractor pricing and construction trends.
Clear Documentation
Every cost plan is structured, easy to understand and supports confident decision‑making.
FAQ Section
What is a construction cost plan?
A cost plan provides a detailed breakdown of expected project costs, helping you understand your budget before work begins.
Do I need a cost plan for an extension or renovation?
Yes — a cost plan helps you avoid cost overruns and ensures your design aligns with your budget.
Are cost plans used for tendering?
No — cost plans are for budgeting and feasibility. Tendering requires a Schedules of Works.
How accurate are your cost plans?
Our cost plans are based on current market rates and real contractor pricing trends in London and the South East.
Need a clear, accurate cost plan for your project?
Send us your drawings or speak to our team for a fixed‑fee proposal.