MYPROJECT
ESTIMATING
CONSTRUCTION ESTIMATE
Single Storey Rear Extension
14 Oakfield Road, London SW00 0AA
£128,788.03 excluding VAT
Contents
- 1. Executive Summary
- 2. Basis of Estimate
- 3. Drawings & Information Relied Upon
- 4. Pricing Summary by Stage
- 5. Preliminaries
- 6. Detailed Stage Breakdown
- 7. PC Sums & Provisional Sums
- 8. Value Engineering Options
- 9. Assumptions
- 10. Exclusions
- 11. Qualifications & Site Verification
- 12. Stage Payment Schedule
- 13. Next Steps
- 14. Standard Terms
1Executive Summary
This report sets out our estimate for the construction of a single storey rear extension at 14 Oakfield Road, London SW00 0AA, providing approximately 42 m² additional floor area. It has been prepared for Mr & Mrs Sample on the basis of the drawings and information listed in Section 2.
Net works£113,971.70
Net total (incl. OH&P + contingency)£128,788.03
Total incl. VAT£154,545.64
The net total of £128,788.03 includes overheads and profit at 8% and a construction contingency at 5%. With VAT at 20%, the total is £154,545.64.
The estimate carries PC and provisional sums totalling £27,414.00 for items not yet finally selected (Section 7). We have also set out value engineering options in Section 8 that could reduce the cost by up to £7,150.00 if adopted.
This is an estimate rather than a fixed-price tender. It should be read together with the assumptions, exclusions and qualifications, which define exactly what is and is not included. All dimensions must be verified on site before ordering or starting work.
Key figure: £128,788.03 net / £154,545.64 including VAT. Valid 90 days.
2Basis of Estimate
This estimate has been prepared on the following basis. Where information was not available, a reasonable allowance has been made and identified as a PC or provisional sum.
| Project | Single Storey Rear Extension — 42 m² additional floor area |
| Location | 14 Oakfield Road, London SW00 0AA |
| Scope | Construction of the extension including groundworks, structure, roof, external envelope, first and second fix, finishes, kitchen and sanitaryware installation, and associated external works. |
| Measurement | Quantities measured from the listed drawings in accordance with NRM2 principles. |
| Pricing | Current UK market labour and material rates at the date of issue. |
| Programme | Single continuous build assumed. No allowance for phasing or accelerated working. |
| Contract | Assumed a standard domestic building contract. Not yet agreed. |
If any of the above changes — in particular a drawing revision or a change of specification — the estimate should be revisited.
3Drawings & Information Relied Upon
This estimate is based on the following drawings and their revisions. Pricing relates to these revisions only. A later revision may change quantities and cost.
| Drawing | Title | Rev | Originator |
|---|
| A-100 | Existing plans and elevations | Rev C | ADE Architecture |
| A-101 | Proposed ground floor plan | Rev D | ADE Architecture |
| A-102 | Proposed elevations and section | Rev D | ADE Architecture |
| A-200 | Proposed roof plan | Rev B | ADE Architecture |
| S-01 | Structural layout and beam schedule | Rev B | Consulting Structural Engineer |
| S-02 | Foundation details | Rev A | Consulting Structural Engineer |
Important: all dimensions shown on these drawings must be confirmed on site before any materials are ordered or works commence. Figured dimensions take precedence over scaled dimensions in all cases.
4Pricing Summary by Stage
The table below summarises the net cost of each stage of the works, excluding VAT. Preliminaries are shown in Section 5 and a full breakdown of every stage follows in Section 6.
| Stage | Net (excl. VAT) |
|---|
| Preliminaries | £17,640.00 |
| Groundworks & Foundations | £10,452.40 |
| Superstructure & Walls | £21,350.00 |
| Roofing | £9,976.00 |
| Windows & External Doors | £8,020.00 |
| First Fix M&E | £6,478.00 |
| Internal Finishes | £15,585.30 |
| Kitchen & Sanitaryware | £17,550.00 |
| External Works | £6,920.00 |
| Net works | £113,971.70 |
| Overheads & profit @ 8% | £9,117.74 |
| Construction contingency @ 5% | £5,698.59 |
| Net total (excl. VAT) | £128,788.03 |
| VAT @ 20% | £25,757.61 |
Total including VAT£154,545.64
5Preliminaries
Preliminaries cover the cost of running the project that is not tied to a single trade — site set-up, management, access, welfare, temporary works and general attendance. They are listed as items and priced for a build of this size and duration.
| Item | Qty | Unit | Rate | Net |
|---|
| Site set-up, welfare unit and temporary fencing | 1 | item | £2,850.00 | £2,850.00 |
| Scaffolding to rear elevation, 12 week hire | 1 | item | £3,420.00 | £3,420.00 |
| Skip hire and waste removal, 6 x 8yd | 6 | each | £285.00 | £1,710.00 |
| Site management and supervision | 12 | week | £640.00 | £7,680.00 |
| Temporary services, protection and general attendance | 1 | item | £1,980.00 | £1,980.00 |
| Total preliminaries | £17,640.00 |
Preliminaries are time-related. A longer programme, or a stop-start programme, would increase this figure.
6Detailed Stage Breakdown
Each stage is broken down into its works. Under every work, costs are grouped into materials, labour and plant. Rates are net of VAT and reflect current UK market prices.
Groundworks & Foundations£10,452.40
Excavation & Disposal£3,516.80
| Description | Qty | Unit | Rate | Net |
|---|
| Labour |
| Reduce level dig and cart away spoil | 38 | m3 | £46.50 | £1,767.00 |
| Excavate for trench fill foundations | 22.4 | m3 | £52.00 | £1,164.80 |
| Plant |
| 3 Tonne excavator hire | 3 | day | £195.00 | £585.00 |
Foundations & Floor Slab£6,935.60
| Description | Qty | Unit | Rate | Net |
|---|
| Material |
| Ready-mix C25 concrete | 22.4 | m3 | £142.00 | £3,180.80 |
| Sand blinding and 1200g DPM | 42 | m2 | £9.80 | £411.60 |
| 100mm PIR floor insulation | 42 | m2 | £21.40 | £898.80 |
| Labour |
| Pour foundations, lay and power-float slab | 42 | m2 | £58.20 | £2,444.40 |
Superstructure & Walls£21,350.00
External Cavity Walls£15,408.00
| Description | Qty | Unit | Rate | Net |
|---|
| Material |
| Facing brick, block and cavity materials | 78 | m2 | £118.00 | £9,204.00 |
| Facing bricks to match existing (PC allowance) | 3.2 | 1000 | £720.00 | £2,304.00 |
| Labour |
| Bricklaying and blockwork to cavity wall | 78 | m2 | £50.00 | £3,900.00 |
Structural Openings£4,330.00
| Description | Qty | Unit | Rate | Net |
|---|
| Material |
| Steel beam to rear opening | 1 | item | £1,650.00 | £1,650.00 |
| Labour |
| Install steel, padstones and make good | 1 | item | £2,680.00 | £2,680.00 |
Internal Partitions£1,612.00
| Description | Qty | Unit | Rate | Net |
|---|
| Material |
| Blockwork and ties | 26 | m2 | £24.00 | £624.00 |
| Labour |
| Build internal partitions | 26 | m2 | £38.00 | £988.00 |
Roofing£9,976.00
Flat Roof Structure£2,520.00
| Description | Qty | Unit | Rate | Net |
|---|
| Material |
| Firrings, joists and 18mm deck | 42 | m2 | £34.00 | £1,428.00 |
| Labour |
| Construct flat roof structure | 42 | m2 | £26.00 | £1,092.00 |
Roof Insulation£1,596.00
| Description | Qty | Unit | Rate | Net |
|---|
| Material |
| 150mm PIR warm roof insulation | 42 | m2 | £28.50 | £1,197.00 |
| Labour |
| Lay and fix insulation boards | 42 | m2 | £9.50 | £399.00 |
Roof Covering£1,680.00
| Description | Qty | Unit | Rate | Net |
|---|
| Material |
| Single-ply membrane and trims | 42 | m2 | £22.00 | £924.00 |
| Labour |
| Install single-ply covering and detailing | 42 | m2 | £18.00 | £756.00 |
Rooflights & Rainwater£4,180.00
| Description | Qty | Unit | Rate | Net |
|---|
| Material |
| Rooflights, 2 no. (PC allowance) | 2 | each | £1,250.00 | £2,500.00 |
| Fascia, soffit and rainwater goods | 1 | item | £980.00 | £980.00 |
| Labour |
| Install rooflights and rainwater goods | 1 | item | £700.00 | £700.00 |
Windows & External Doors£8,020.00
Bi-fold Doors£4,680.00
| Description | Qty | Unit | Rate | Net |
|---|
| Material |
| Aluminium bi-fold doors, 3.6m (PC allowance) | 1 | each | £4,200.00 | £4,200.00 |
| Labour |
| Install bi-fold door set and make good | 1 | each | £480.00 | £480.00 |
Windows£3,340.00
| Description | Qty | Unit | Rate | Net |
|---|
| Material |
| Double glazed windows, 4 no. (PC allowance) | 4 | each | £680.00 | £2,720.00 |
| Labour |
| Install windows and make good | 4 | each | £155.00 | £620.00 |
First Fix M&E£6,478.00
Electrical First Fix£2,450.00
| Description | Qty | Unit | Rate | Net |
|---|
| Labour |
| First fix electrics to extension | 1 | item | £2,450.00 | £2,450.00 |
Plumbing & Heating First Fix£2,180.00
| Description | Qty | Unit | Rate | Net |
|---|
| Labour |
| First fix plumbing and heating, 3 radiators | 1 | item | £2,180.00 | £2,180.00 |
Underfloor Heating£1,848.00
| Description | Qty | Unit | Rate | Net |
|---|
| Material |
| Underfloor heating kit | 42 | m2 | £18.00 | £756.00 |
| Labour |
| Install underfloor heating | 42 | m2 | £26.00 | £1,092.00 |
Internal Finishes£15,585.30
Plastering & Screeding£6,921.30
| Description | Qty | Unit | Rate | Net |
|---|
| Material |
| Plasterboard, skim and screed materials | 1 | item | £2,400.00 | £2,400.00 |
| Labour |
| Plaster, skim and screed | 210 | m2 | £21.53 | £4,521.30 |
Floor Finishes£2,814.00
| Description | Qty | Unit | Rate | Net |
|---|
| Material |
| Floor finish supply (PC allowance) | 42 | m2 | £45.00 | £1,890.00 |
| Labour |
| Prepare and lay floor finish | 42 | m2 | £22.00 | £924.00 |
Decoration & Second Fix Joinery£5,850.00
| Description | Qty | Unit | Rate | Net |
|---|
| Labour |
| Painting and decorating throughout | 1 | item | £3,200.00 | £3,200.00 |
| Second fix joinery, skirting and architrave | 1 | item | £2,650.00 | £2,650.00 |
Kitchen & Sanitaryware£17,550.00
Kitchen£14,400.00
| Description | Qty | Unit | Rate | Net |
|---|
| Material |
| Kitchen units and worktops (PC sum) | 1 | sum | £12,000.00 | £12,000.00 |
| Labour |
| Install kitchen and connect appliances | 1 | item | £2,400.00 | £2,400.00 |
Sanitaryware£3,150.00
| Description | Qty | Unit | Rate | Net |
|---|
| Material |
| Sanitaryware to WC (PC sum) | 1 | sum | £1,800.00 | £1,800.00 |
| Labour |
| Second fix plumbing and sanitaryware | 1 | item | £1,350.00 | £1,350.00 |
External Works£6,920.00
Patio & Landscaping£3,850.00
| Description | Qty | Unit | Rate | Net |
|---|
| Labour |
| Rebuild patio and level rear garden | 1 | item | £3,850.00 | £3,850.00 |
Drainage£1,420.00
| Description | Qty | Unit | Rate | Net |
|---|
| Labour |
| Drainage connections and gullies | 1 | item | £1,420.00 | £1,420.00 |
Making Good£1,650.00
| Description | Qty | Unit | Rate | Net |
|---|
| Labour |
| Make good at junction with existing house | 1 | item | £1,650.00 | £1,650.00 |
7PC Sums & Provisional Sums
The items below are allowances, not fixed prices. A Prime Cost (PC) sum is money set aside for materials or fittings not yet finally selected. A provisional sum is money set aside for work that cannot yet be precisely measured. Each is reconciled against the actual cost once selections and details are confirmed.
| Item | Type | Allowance (excl. VAT) |
|---|
| Facing bricks to match existing | PC Sum | £2,304.00 |
| Rooflights (2 no.) | PC Sum | £2,500.00 |
| Aluminium bi-fold doors, 3.6m | PC Sum | £4,200.00 |
| Windows to extension (4 no.) | PC Sum | £2,720.00 |
| Floor finish supply | PC Sum | £1,890.00 |
| Kitchen units and worktops | PC Sum | £12,000.00 |
| Sanitaryware to WC | PC Sum | £1,800.00 |
| Total allowances | £27,414.00 |
These allowances are already included within the stage prices and the totals in Section 4. They are listed here so you can see exactly which items are still to be confirmed. Final cost may be higher or lower depending on your selections.
8Value Engineering Options
The following options could reduce the cost without changing the size or layout of the extension. They are optional. Each shows the saving against the net total and a short note on the trade-off. We are happy to talk any of them through.
| Option | Area | Saving |
|---|
| Single-ply membrane roof → high-performance felt system Reduces roof cost with a proven felt build-up. Slightly shorter guarantee period. | Roofing | −£1,260.00 |
| Aluminium bi-fold → uPVC French doors with side lights Lower-cost door set. Reduces the opening's slimline appearance. | Windows | −£2,350.00 |
| Porcelain floor tiles → engineered timber / LVT Alternative floor finish at a lower supply rate. Subject to selection. | Finishes | −£840.00 |
| Standard rooflights → fixed frameless units Fixed instead of opening rooflights. Loses ventilation via the roof. | Roofing | −£700.00 |
| Client-supplied kitchen (trade discount retained by client) Client procures kitchen directly. MPE installs only. Removes our PC margin. | Kitchen | −£2,000.00 |
| Maximum saving if all options adopted | −£7,150.00 |
Net total as estimated: £128,788.03 → with all options: £121,638.03 (excl. VAT)
9Assumptions
This estimate is prepared on the following assumptions. If any prove incorrect, the price may change.
- Pricing is based on the drawings and revisions listed in the Basis of Estimate. Any subsequent revision may change the price.
- Works are assumed to proceed continuously, with clear and uninterrupted access to the rear of the property throughout.
- Existing foundations, drains and services are assumed sound and in the positions indicated. Any diversions are excluded.
- Ground is assumed to be firm and free from rock, running water, contamination or made ground. Standard trench-fill depths assumed.
- Existing walls where the extension connects are assumed sound and suitable to be built off and made good.
- Mains water, drainage and electricity are available at the property and of adequate capacity.
- All PC and provisional sums are allowances only and will be reconciled against actual selections and costs.
- Working hours are standard weekday hours. No allowance is made for weekend, night or accelerated working.
10Exclusions
The following are not included in this estimate. If any are required, they can be priced separately on request.
- VAT reliefs or zero-rating (priced at standard rate unless confirmed otherwise)
- Party wall awards, surveyor fees and any associated works
- Planning fees, building control fees and statutory charges
- Architect, structural engineer and other consultant fees
- Asbestos survey, removal or licensed disposal
- Removal of unforeseen obstructions, rock, contaminated or made ground
- Diversion or upgrade of existing incoming services and meters
- Tree removal, root protection measures and arboricultural works
- Landscaping and planting beyond the patio and levelling stated
- Loose furniture, white goods and appliances (unless within a stated PC sum)
- Works to the existing house beyond making good at the junction with the extension
- Temporary alternative accommodation for the client during the works
11Qualifications & Site Verification
This estimate is issued subject to the following qualifications.
- All dimensions and quantities are taken from the drawings listed and MUST be verified on site before any materials are ordered or works commence.
- This is an estimate, not a fixed-price tender. Final cost is subject to confirmed selections, site conditions and any design development.
- Where a specification is not yet fixed, a reasonable allowance has been made and flagged as a PC or provisional sum.
- Structural elements are priced to the engineer's current design. Any change following building control review may affect the price.
- The estimate assumes a single continuous build programme. A phased or stop-start programme would be repriced.
- Prices are held for the validity period stated on the cover. Beyond that, material prices in particular are subject to review.
All dimensions and quantities are taken from drawings and MUST be verified on site before any materials are ordered or works commence. Figured dimensions take precedence over scaled dimensions.
12Stage Payment Schedule
On acceptance we would propose the following stage payments, each due on completion of the stage and against a valuation. Percentages are of the net total (excl. VAT). VAT is added to each payment.
| Stage | % | Net amount |
|---|
| Mobilisation / deposit on acceptance | 10% | £12,878.80 |
| Groundworks and foundations complete | 20% | £25,757.61 |
| Superstructure and roof watertight | 25% | £32,197.01 |
| First fix M&E and plastering complete | 20% | £25,757.61 |
| Second fix, kitchen and finishes complete | 20% | £25,757.61 |
| Practical completion and snagging signed off | 5% | £6,439.40 |
| Net total | 100% | £128,788.03 |
This is an indicative schedule for discussion. Final stage payments are agreed and set out in the building contract.
13Next Steps
To move this forward:
- Review this estimate and the assumptions, exclusions and qualifications in full.
- Confirm any PC and provisional sum selections so those allowances can be firmed up.
- Let us know which, if any, value engineering options you would like us to apply.
- On acceptance, we issue a contract sum, programme and a stage payment schedule.
- Contact us with any queries and we will be happy to talk them through.
We look forward to hearing from you.
My Project Estimating
info@myprojectestimating.co.uk • [phone number]
myprojectestimating.co.uk
14Standard Terms
This estimate is issued on the following terms. It is an estimate of likely cost based on the information available at the date of issue and is not a fixed-price tender or an offer to contract. Prices are held for 90 days from the date of issue, after which they are subject to review, in particular material prices. Quantities are measured from the drawings listed and must be verified on site before ordering or commencing works. PC and provisional sums are allowances only and are reconciled against actual cost. The assumptions, exclusions and qualifications in this report form part of the estimate and define its scope. No liability is accepted for matters outside the stated scope or for changes arising from revised information, site conditions or design development. Any contract arising will be documented separately and will take precedence over this estimate.