Extension Cost Calculator

Scotland 2026 | Professional Cost Estimate

Client Information
Project Details
Build cost includes: foundations, drainage, walls, insulation, roof, standard windows/doors, first-fix electrics & plumbing, plasterboard/plaster, basic finishes.
Not included: kitchens, bathrooms, high-end finishes, landscaping, professional fees, VAT.
Surveys & Site Investigation
Professional Fees

Note: Structural Engineer and Quantity Surveyor fees shown are indicative estimates based on typical UK market rates (2026). Actual fees vary depending on project complexity, scope of services required, and individual consultant pricing.

Architect fees by RIBA stage: Fees can be calculated as percentage of construction cost or as fixed fees for each stage. Total fees across all stages typically sum between 8-15% of construction cost (for listed buildings up to 17% and higher). The smaller project potentially the higher fees and vice versa.
Architect Fee Tier:
Calculating...
Concept Design (RIBA Stage 2)
Planning Application (RIBA Stage 3)
Building Warrant (RIBA Stage 4)
Tender Support (RIBA Stage 5)
Construction Oversight (RIBA Stage 6)
Statutory Fees
Contingency
Contingency covers unexpected costs during construction (site conditions, specification changes, unforeseen structural work).
Cost Breakdown
Build Cost (ex VAT) £0
Kitchen £0
Bathroom £0
Structural Openings £0
Total Construction Cost (ex VAT) £0
Contingency £0
Construction + Contingency (ex VAT) £0
VAT (20%) £0
SUBTOTAL: Construction (inc VAT) £0
Ordnance Survey Maps £0
Measured Survey £0
Ground Survey £0
SUBTOTAL: Surveys & Site Investigation £0
Bill of Quantities £0
Structural Engineer £0
Architect - Concept Design £0
Architect - Planning Application £0
Architect - Building Warrant £0
Architect - Tender Support £0
Architect - Construction Oversight £0
SUBTOTAL: Professional Fees £0
*Professional fees shown include VAT where providers are VAT registered (indicated by checkboxes above)
Planning Permission Fee £0
Building Warrant Fee £0
SUBTOTAL: Statutory Fees £0
TOTAL PROJECT COST (inc VAT) £0
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