Single-Storey Extensions

Thinking about a single-storey extension? Whether you are planning a rear extension, side return, kitchen-diner, family room, utility space or home office, EvoHome Improvements helps you understand your options and plan a sensible next step. We advise on common considerations such as planning permission or permitted development, building regulations, structural calculations, drawings and surveys, then coordinate comparable written quotations from vetted independent builders and specialists who carry out the physical work.

We support homeowners across Hampshire and the wider South of England, and aim to make the early stages clearer, calmer and less salesy — no guaranteed approvals, no fixed prices without proper assessment, and no pressure. A home extension represents one of the most significant investments a homeowner can make — and in Hampshire's strong property market, it is often more cost-effective than moving.

With average house prices in Winchester exceeding £500,000, even a substantial extension budget can represent better value than stamp duty, moving costs, and the price premium on a larger property. ## Planning and Permitted Development in Hampshire Many single-storey rear extensions fall within Permitted Development rights, meaning planning permission is not required.

However, the rules are complex — particularly regarding height, depth, boundary distances, and conservation area restrictions. Winchester, with its extensive conservation areas, and the South Downs National Park both impose additional planning constraints that homeowners must navigate carefully. ## Building Regulations Compliance Unlike planning permission, Building Regulations approval is always required for extensions.

This covers structural integrity (Part A), fire safety (Part B), energy efficiency (Part L), ventilation (Part F), and drainage (Part H). A good builder will manage this process, but the homeowner should understand what inspections are required and ensure they are completed at each stage. ## Cost Management and Budgeting The most common source of extension project stress is budget overrun.

This typically occurs because initial quotes exclude professional fees, internal finishes, kitchen/bathroom fitting, electrical rewiring, and decoration. A realistic budget should include: architect/designer (£3,000–£8,000), structural engineer (£500–£1,500), building control (£500–£1,000), party wall surveyor (£700–£1,500), and a 15–20% contingency.

## The Hampshire Construction Market Hampshire's construction market is competitive, with demand consistently exceeding supply of quality builders. Lead times of 3–6 months are common for reputable contractors. Starting the design and planning process early — typically 6–12 months before your desired build date — gives you the best choice of builders and avoids the premium pricing that comes with urgent timescales.

## Extension Types and What They Suit - Single-storey rear: the most common way to gain kitchen and living…