Building on a Budget — How to Get More From Your London Build

The single most powerful tool for staying on budget is a well-defined scope. Vague briefs produce vague estimates. A vague estimate cannot be held to.

Before going to contractors:

• Write down exactly what you want to achieve
• Distinguish between must-haves and aspirational additions
• Have an architect or designer draw the layout — even a simple sketch helps
• Ask your structural engineer to identify the key structural elements early

A clear brief produces competitive, comparable quotes that protect you commercially and give contractors the information they need to price accurately.

Value engineering is the process of achieving the same functional result at lower cost by changing how something is designed, specified, or procured. It is not simply buying cheaper things.

Examples of genuine value engineering:

Structural openings: A beam spanning 3m costs significantly less than one spanning 5m. If your layout allows, a post in the middle of an opening can halve the structural cost with minimal lifestyle impact.

Foundation type: Piled foundations cost significantly more than strip or pad foundations. A ground investigation might confirm that the cheaper foundation type is adequate — saving tens of thousands of pounds.

Roof structure: A flat-roofed extension typically costs less than a pitched extension of the same footprint. The addition of a rooflight brings in comparable light at lower total cost than a pitched roof with large rooflights.

Glazing: Aluminium bifold doors are significantly more expensive than aluminium sliding or casement doors of comparable width. If the desire is to open the space to the garden, a single large sliding door may achieve 90% of the same effect at lower cost.

External facing materials: Silicone render or painted brickwork can achieve a very similar aesthetic to much more expensive stone cladding or specialist finishes.

Some elements of a construction project are false economies to reduce. These include:

Structural design: A properly engineered structure is not where to save money. An undersized beam, inadequate foundation, or poorly designed connection creates risk and is expensive to fix.

Waterproofing: Cutting corners on the flat roof membrane, the junction between extension and house, or the basement tanking system leads to leaks that are disproportionately expensive to repair.

Thermal insulation: Poor insulation is a running cost forever. Building to current standards costs modestly more and pays back over years of lower energy bills.

Electrical first-fix: Running cables and conduits during construction is cheap. Accessing them once everything is plastered and decorated is expensive. Do it right the first time.

Building Regulations compliance: Works that fail building control inspection require remedial works. Non-compliant works affect property sales and may require rectification to sell.

If budget is tight, phasing is often the best strategy. Rather than doing a large project badly, do a smaller project to a high standard and build the next phase when funds allow.

Example phasing for a kitchen extension and loft conversion:

• Phase 1 (now): Rear extension only, full kitchen fit-out, bifold doors, rooflight
• Phase 2 (2 years later): Loft conversion with dormer, bedroom and en-suite

Each phase is designed to be complete in itself. The structure for Phase 2 is considered in Phase 1 so that no rework is needed.

Phasing works best when:

• The phases are natural building stages
• Each phase is designed as a complete unit
• The overall vision is clear from the start so each phase is designed within the whole

Construction prices in London are driven partly by demand. Historically, a project started in autumn or winter (when demand from developers is lower) can achieve better contractor availability and sometimes better pricing than one started in spring.

This is not always reliable — many clients want works done in summer when children are not in school or when outdoor access is easier. But where timing is flexible, this is worth considering.

Design-and-build vs. traditional procurement: Design-and-build (one contract, one team) is often more cost-effective for domestic refurbishments because it eliminates the gap between design intent and buildability, reduces professional fees for separate contract administration, and gives the homeowner a single point of responsibility.

Package deals: Certain elements — kitchens, bathroom pods, glazing packages — can often be procured more cost-effectively as packages direct from suppliers than through the main contractor. Discuss this with your contractor early: some will allow client-direct procurement for specified elements.

Materials supply: Buying materials direct from a merchant (rather than through the contractor) is sometimes cheaper but comes with risks — you bear the risk of material errors, delays, and storage.

Floor finishes: Porcelain floor tiles are extremely competitive in price and durability. Budget to mid-range porcelain in a 600x600mm or 600x1200mm format can look as good as much more expensive stone at a fraction of the cost.

Kitchen units: The quality of cabinet carcasses matters more than the brand. Trade-quality carcasses with good paint finishes and mid-range doors can achieve the visual result of a premium kitchen at 40–50% of the cost.

Sanitaryware: Entry-level sanitaryware from quality suppliers (VitrA, Ideal Standard, Roca) performs as well as top-end brands. The biggest difference is in the tap and shower specification — focus spend here.

Internal doors: FD30 solid core doors in a simple design look good and are fire-rated. Avoid very cheap hollow-core doors — they sound hollow and feel cheap.

Lighting: LED downlights are extremely cost-effective. The fitting cost matters much less than the quality of the light output and colour temperature (warm white at 2700K or 3000K for living spaces).

Budget overruns on site often come from:

• Scope changes instructed during the works
• Unforeseen conditions not covered by contingency
• Delays causing extended preliminaries (scaffolding, site facilities)

To protect your budget:

• Freeze the scope before work starts
• Do not add items to the contract unless they are essential
• Monitor the cost plan monthly
• Require formal variation orders for every change, even small ones
• Address unforeseen conditions quickly and practically — delays cost more than swift decisions

rcbGroup approaches every project with a design-to-cost mindset — meaning we consider commercial impact at every design stage, not just at the end. Our pre-construction process is designed to surface and resolve cost issues before the project starts, not mid-build.

We offer early-stage budget reviews, value engineering input during the design phase, and transparent cost planning that allows you to make informed decisions before committing to a contract.