Rear Extension in Cricklewood NW2

Why Cricklewood Properties Choose Us

More affordable, good Victorian stock. Up-and-coming with significant regeneration plans. Our team works exclusively in NW London, bringing detailed knowledge of Barnet planning requirements and the specific challenges of Victorian terraces stock.

Planning Authority

Barnet LBC

Average Property Value

£550,000

Conservation Area

No

Typical Project Cost

£65,000–£140,000

How a Rear Extension Works — Step by Step

1. 1

   Site Survey and Design Brief

   We survey the rear garden, measure existing room layouts, and establish the maximum footprint permitted by the planning authority. We confirm the position of any drainage runs, manholes, and underground services that will affect foundation design. From this we establish the design brief with your architect.

2. 2

   Planning Application or Permitted Development Confirmation

   In conservation areas and Article 4 zones, full planning permission is required. Where PD rights exist, we apply for a Lawful Development Certificate to confirm permitted development status before work starts — protecting your investment against future challenges at sale. We manage the full planning or LDC process.

3. 3

   Architectural Design

   A RIBA architect produces construction drawings including floor plans, sections, elevations, and roof details. In conservation areas the external materials — brick, render, glazing — are selected to satisfy the design requirements of the planning authority. Full plans are submitted to building control alongside the structural engineer's calculations.

4. 4

   Structural Engineering and Foundation Design

   A structural engineer designs the foundations (strip, pad, or raft depending on soil conditions), the steel or timber frame for the roof structure, and any steels required to open up the rear wall. London Clay conditions are well understood by our engineers — foundation depths of 1.0–1.5m are typical but may be deeper near trees.

5. 5

   Groundworks and Foundations

   Excavation commences for the extension footprint, any utility diversions are completed, and the foundations are poured. Underground drainage runs are laid to connect the new extension's soil stack and ground drainage to the existing drain. Building control inspects the foundations before pouring commences.

6. 6

   Superstructure, Roof, and Weatherproofing

   Blockwork walls are built from the foundation up. The roof structure — typically a flat warm roof or a lean-to with a conservation rooflight — is constructed and made weathertight before any internal work begins. External cladding or render is applied and external joinery installed.

7. 7

   Rear Wall Opening and Steel Installation

   With the extension weather-tight, the existing rear wall is opened up under the new structural steel lintel or frame. Temporary props support the structure while the masonry is removed. The new bifold, sliding, or fixed glazing is installed, transforming the connection between house and extension.

8. 8

   First Fix, Screed, and Internal Fit-Out

   First fix electrics, underfloor heating pipes, and plumbing are installed before the screed is poured. Insulation to Part L standards is fitted. Plastering, second fix, kitchen installation, and decoration follow. Building control issues the completion certificate at sign-off, confirming compliance.

Rear Extension in Cricklewood — Planning and Local Considerations

Cricklewood spans the Barnet/Brent boundary — the LPA for any given address must be confirmed before commissioning design work. Both Barnet and Brent are significantly more permissive than Camden for single-storey rear extensions, and PD rights are generally intact for standard extension sizes. The Victorian and Edwardian terrace stock in NW2 is structurally well-suited to rear extensions. Value-for-money is a key differentiator — the same project in Cricklewood costs 15–25% less than in NW3.

Frequently Asked Questions