Select a common project archetype below or customize your parameters from scratch.
Open-plan rear extension with bifold doors and skylights.
Rear dormer loft conversion with en-suite bedroom.
Full internal renovation plus ground-floor extension.
Custom multi-storey replacement dwelling (VAT Exempt).
Notice: New build properties assumed VAT exempt. Extensions/renovations include 20% VAT within base rates.
Gross Internal Area (GIA):
Total area measured from the internal face of external perimeter walls.
Include halls & stairs. Exclude external walls & open balconies.
Pre-construction management, regulatory feasibility, and unified consultant allocation.
Your project parameters align with standard Permitted Development rights. A Lawful Development Certificate is advised prior to tender to prove legal compliance.
A breakdown of required specialists, estimated costs, and key hiring stages.
Legal protections, stage payment cash flow, and builder tender vetting before signing.
Notice: Having your Architect or QS act as Contract Administrator ensures independent site valuations before you release stage payments.
Designed specifically for residential projects. Protects your deposit, enforces completion dates, and sets clear liquidated damages if the builder runs late.
Retention Explained
A percentage (3% to 5%) withheld from payments. Half released at completion; half held until end of defects period to ensure snagging fixes.Defects Period Explained
A set timeframe (6 to 12 months) post-completion where the contractor must return to fix any defects or shrinkage at zero extra cost.Complete all 5 sequential due diligence checks before signing contracts or releasing funds.
Pre-construction decisions, long-lead factory orders, and Prime Cost (PC) sum budget variance control.
Adjust individual item budgets below to see how choices impact your contingency fund.
Ensure glazing, kitchens, and steel orders are signed off early to prevent site stoppage.
Select your chosen products to calculate factory lead times and set sign-off target dates.
Compare default contract allowances against actual quotes or high-end choices.
On-site execution stages, lead-time factors, and programme forecast.
Groundworks, foundations, masonry walls, steel RSJs, roof structure, and weatherproofing.
Site Prep & Clearance
Demolition, hoarding, welfare setup, skip placement, and ground clearing.Foundations & Slab
Trench digging, inspector sign-off, concrete pour, and floor slab laying.Brick & Blockwork
Cavity wall construction, wall ties, lintels, and damp-proof course (DPC).Structural Steelwork
Steel beam hoisting, padstone setting, goalpost frames, and fire casing.Roof Coverings
Rafter/truss framing, membrane, battening, tiles/slates, and lead flashing.Windows & Doors
External window fitting, bifold door frames, rooflights, and sealing.Internal partition framing, cable routing, plumbing runs, underfloor heating, and plasterboarding.
Carpentry First Fix
Timber/metal stud partitions, joist leveling, and door lining frames.Electrical Cables
Consumer unit prep, ring mains, lighting circuits, and backbox chasing.Plumbing 1st Fix
Supply pipes, soil stacks, gas lines, and underfloor heating loops.Insulation Layers
Rigid PIR boards and acoustic wool fitted to walls, floors & ceilings.Plasterboarding
Fire-rated & moisture-resistant plasterboards fixed to studs & masonry.Plaster Skimming
Joint taping, angle bead fixing, and two-coat multi-finish plaster skim.Kitchen/bathroom fitting, second-fix joinery, floor coverings, tiling, decorating, and final sign-off.
Kitchen Installation
Cabinetry fitting, worktop installation, island assembly, and appliances.Sanitaryware Fit-out
Baths, shower enclosures, WC units, basins, and valve connections.Second Fix Joinery
Internal doors, architraves, skirting boards, handles, and stair spindles.Second Fix MEP
Switch faceplates, downlights, radiator hanging, and boiler fire-up.Tiling & Flooring
Wall tanking, porcelain floor tiling, grouting, and engineered wood.Painting & Decorating
Plaster mist-coating, wall emulsion, and woodwork satin painting.Cascading schedule showing sequential project phases, lead times, and critical path milestones.
Design, surveys, permissions & tender vetting.
Demolition, substructure to final decoration.
Full journey duration from dreaming to keys in hand.
Practical completion certification, retention release calculation, and statutory O&M documentation binder.
Site risk and building insurance responsibility transfer back to the homeowner on this date.
At Practical Completion, 50% of the withheld retention fund (2.5% of net build) is released to the main contractor. The remaining 50% is safely held in trust until the Defects Liability Period expires.
Mandatory certificates, energy ratings, and equipment guarantees required before final payment sign-off.
Final legal certificate confirming compliance with UK Building Regs.
Boiler commissioning certificate & pipework pressure test pass.
Mains consumer unit test results & fixed wiring completion cert.
Final Energy Performance Certificate & As-Built SAP rating compliance.
Solar PV, battery, or heat pump commissioning & DNO registration.
10-25yr flat roof, glazing, bifold door, and boiler warranty cards.
Post-handover defects liability management, seasonal drying-out monitoring, and contractor snagging log.
Log defect items room-by-room and export an official signature sheet for contractor rectification.
Advice goes here.