Building Regulations Approved – Rear Extension in Chorley:

Compliant, Comfortable, and Ready to Build

At Melrose Designs, we’re proud to support homeowners through every stage of their extension project—from initial concept to Building Regulations approval. One of our latest projects, located on Pincock Street in Chorley, showcases a beautifully detailed rear extension that combines smart design with full regulatory compliance.

Here’s a closer look at what went into the Sunningdale rear extension and how we ensured it met all the technical and safety standards.

Building Regulations Approved – Strong Foundations and Structural Safety

The project involved a single-storey rear extension designed to expand the ground floor living space. Foundations were specified to a minimum 900mm depth to comply with Building Control requirements and accommodate local ground conditions. Load-bearing structural beams (2No. 178x102x19 UB’s) were designed to support the new opening, resting on concrete padstones and fire-protected with double-layer plasterboard.

We also detailed appropriate roof construction, including 150x50mm C24-grade softwood rafters and twin 250x75mm ridge beams bolted at 600mm centres. These elements are tied with steel straps and supported by joist hangers for long-term durability and wind resistance.

Warm, Energy-Efficient Living Space

Thermal efficiency was a key priority. The extension’s walls are highly insulated, incorporating 75mm Kingspan Kooltherm within the cavity, aerated Thermalite Turbo blocks, and insulated cavity closers—all helping to achieve a wall U-value of just 0.18 W/m²K.

The roof space features 400mm of layered quilt insulation, and the new floor includes 100mm rigid board insulation plus a damp-proof membrane. Double glazed, argon-filled windows and doors with low U-values further reduce heat loss and improve energy performance.

Modern Materials and Detailing

Every detail has been considered. From eaves ventilation (25mm continuous strip vents) to robust cavity trays and damp-proof courses (DPCs) 150mm above ground level, the drawing is packed with practical solutions to moisture control and long-term stability.

All lintels, cavities, fire protection, and structural wall ties are included in line with British Standards, offering reassurance to both contractors and Building Control officers.

Future-Proof Services and Safety Features

The extension will include modern plumbing, electrics, and heating, with all installations carried out by certified specialists. The design complies with Part P (Electrical Safety) and Part M (Accessibility) of the Building Regulations.

Fire protection features include a ½-hour rated structure and safety glazing to all low-level windows. Ventilation has also been carefully considered, with trickle vents in all new windows and mechanical extract ventilation in accordance with Part F.

Ready to Build in Chorley

With this detailed Building Regulations drawing package, the client now has full approval to proceed. The extension will offer a comfortable, modern living area that’s built to last—and built right.

If you’re thinking about a home extension in Chorley, Wigan, or the surrounding areas, we can help guide your project through every step—from design to compliance.