How Sixes uses these figures
We publish a broad range because an honest early budget is more useful than a low headline figure that excludes essential work. These allowances combine the scope customers commonly ask us to consider with the practical variables we see when reviewing rooms, drawings and existing properties across West Sussex.
They are intended to answer one question before detailed design begins: is the outcome you want reasonably aligned with the budget available? If it is, photographs, approximate dimensions and a short description let us have a more productive first conversation.
Typical planning ranges
Simple or shell-led build
Around £1,800–£2,800 per m²A straightforward form and controlled specification could fall within this bracket.
Complete higher-spec extension
Around £2,800–£4,500+ per m²Glazing, bespoke details, services and interior fit-out affect the total.
Fees & contingency
Often allow 10–20%The right allowance depends on design stage, surveys and known site conditions.
What changes the price?
- Ground conditions and access
- Steelwork and structural openings
- Glazing, kitchen and finishes
- Design, approvals and service upgrades
What a useful quotation should make clear
Compare the written scope rather than the final number alone. Check who supplies each item, what preparation and making good are included, which assumptions rely on unseen conditions, how variations are agreed and whether VAT is included. For larger work, professional fees, statutory approvals and contingency should sit visibly beside the construction figure.
Figures are broad, VAT-inclusive homeowner planning allowances where applicable—not quotations or offers. Site conditions, design, specification, access and third-party costs can materially change the total. A written quotation follows confirmed scope and measurement.