Construction terms glossary for homeowners: costs, stages and project management
You should not need to learn a new language to make decisions about your home. But when an architect talks about a cost plan, a builder includes a provisional sum, or someone says the price is fixed, the meaning matters.
This construction terms glossary explains the language of cost planning, project stages, tendering and management. It focuses on what the terms mean for your money, decisions and responsibilities when building, extending or renovating a home.
Use the sections below to find what you need. These are plain-English explanations; the meaning and process in your own project depend on the documents and appointments you agree.
Find the term you need
Cost planning and budgets
Project budget
The total amount you can commit to the project. It needs to cover the building work and the other costs you will pay: professional fees, surveys, approvals, VAT where applicable, your own purchases and a sensible allowance for risk. Decide what is inside that budget before discussing whether a scheme is affordable.
Construction cost
The cost of carrying out the building work, on a stated basis. It is only part of the overall project budget. Always check whether the figure includes the contractor’s site costs, overheads and profit, and whether VAT is included or added separately.
Budget estimate
An early assessment of likely cost using the information available. It helps test whether the brief and available money broadly fit together before you commit to detailed design. The scope, assumptions, price date and allowances should be visible, so you know what the figure represents.
Elemental Cost Plan (ECP)
An estimate organised into the main parts of the building work, with quantities, rates and allowances developed from the design. Its purpose is to give you a realistic view of the likely end cost and help you make decisions while there is still room to change the design.
At Multiproject, our rates draw on real project data and current market rates. We prepare close to 200 ECPs a year and track comparisons with reputable builders pricing the same full scope. The figures are typically reasonably close; we use those comparisons to monitor accuracy and market changes.
For a refurbishment, extension and loft conversion, we typically show these areas separately, each with its own elemental breakdown. That lets you compare the cost of the loft, extension and internal works, then test where you want to spend. The report should make wider allowances and any exclusions clear.
Read our cost plan guide, with example extracts.
Cost check
A review of the likely cost of a design or proposed change against the budget or previous cost plan. It is most useful before a decision becomes expensive to reverse. A cost check might reveal that a layout change affects structure, services and finishes as well as the item you first had in mind.
Cost per square metre (£/m²)
A total cost divided by a defined floor area (typically gross internal floor area that includes most walls, stairs, etc). It can help with early comparisons, but it is only meaningful if the projects, area measurements and included costs are comparable. A small extension with substantial work to the existing house can look expensive per square metre without being poorly priced.
Contingency and risk allowance
Money set aside for uncertainty and identified risks. The allowance should reflect what is known about your project and reduce or change as risks are resolved. Known work belongs in the estimate; leaving it out and hoping contingency will cover it gives you a misleading starting point.
Provisional sum
An allowance for work that cannot yet be priced firmly because its scope or detail is insufficiently defined. The amount is dealt with under the contract as the work becomes clearer. Ask what it covers, why it is provisional and what information is needed to resolve it.
Prime cost sum (PC sum)
An allowance commonly used for the supply of items you have not selected, such as sanitaryware or tiles. In that case, installation and other additions need to be accounted for separately. Check the document’s definition: the same label is sometimes used differently. An unrealistically low allowance makes the headline price look better without making your choices cheaper.
Preliminaries
The contractor’s project and site running costs, such as supervision, temporary facilities, protection and site establishment. They are needed to deliver the work even though they do not become part of the finished house. Some depend on duration, so a longer programme can affect the cost.
Overheads and profit (OHP)
An allowance for the contractor’s wider business costs and profit. It may be built into rates or shown separately. Compare the complete price on a consistent basis; a lower percentage on one line does not necessarily mean a better overall offer.
Inflation allowance and price date
The price date tells you when the estimate’s rates apply. An inflation allowance makes provision for expected price movement over a stated period. A cost plan prepared now should explain how it treats a project that will be tendered or built later.
Assumptions and exclusions
Assumptions are the things a price or estimate takes to be true. Exclusions are the things it leaves out. Both need to be explicit. Work excluded from a builder’s price may still be necessary and still need funding within your overall project budget.
Value engineering
Testing alternative ways to achieve what matters to you, considering cost, quality, performance and future use. It works best as part of design development. Reducing an allowance on paper without changing the work or your expectations does not create a real saving.
The brief, design and project stages
Project brief
A statement of what you want the project to achieve, your priorities, constraints and available budget. It should explain how you want to live, not just list rooms. The brief can develop as you explore options, provided the design and budget develop with it.
Feasibility study
An early examination of whether an idea is practical and worth pursuing. It brings together the brief, site or building constraints, likely costs, timing and the options available. Establishing feasibility early gives you a better basis for deciding what to design.
Concept design
The stage of exploring the overall approach: layout, scale, appearance and how the spaces work together. Cost advice at this point helps you compare options before investing in one direction. A concept drawing is not usually enough information for a dependable, detailed building price.
Spatial coordination and developed design
The work of bringing the layout, structure and building services together so they fit and function as a coordinated design. You may hear the older expression ‘developed design’. This is an opportunity to resolve conflicts and update the cost plan before the technical detail is completed.
Technical design
The detailed information explaining how the project is to be built, including coordinated drawings and specifications. Who prepares each part depends on the appointments and procurement route. Agree those responsibilities: a drawing package can look substantial while still leaving important design decisions unresolved.
RIBA stages
A commonly used framework for organising a building project, from deciding what is needed through briefing, design, construction, handover and use. The stages help a team describe progress, but a stage label does not tell you exactly what someone has been appointed to deliver. Check the agreed deliverables and responsibilities.
The RIBA Plan of Work sets out the framework.
Planning permission and building regulations approval
These deal with different questions. Planning considers whether proposed development is acceptable in planning terms; building regulations set requirements for matters such as safety, accessibility and energy performance. Approval under one process does not replace the other, and a planning drawing is not automatically a complete construction or tender package.
The government’s building regulations guide explains the distinction for England; requirements and procedures differ across the UK.
Party wall and party wall notice
A shared wall or structure can bring proposed work within the Party Wall etc. Act 1996 in England and Wales. The Act also covers certain boundary work and nearby excavation. Where it applies, notices and the relevant procedures need dealing with before the affected work starts. Allow for these in your programme and budget; planning permission does not replace them.
Check the government’s party wall guidance early in the design process.
Party wall award
A document made by the appointed surveyor or surveyors to resolve a dispute under the Party Wall Act. It sets out matters such as the work covered and how and when it may proceed. It is different from a neighbour simply consenting to a notice, and does not replace other necessary approvals.
Schedule of condition
A written and photographic record of a property’s condition before work starts. It can help establish whether damage was already present. Often prepared for neighbouring areas that may be affected by party wall work, it records condition; it does not describe or price the proposed building work.
Pre-construction
The preparation before building work starts: developing the design, investigating the site, planning costs and timing, obtaining relevant approvals, appointing the team and agreeing the building contract. Starting on site before this work is ready can move unresolved decisions into the most expensive part of the project.
Pricing documents and choosing a builder
Scope of works
The work to be carried out, including its extent, quality and boundaries. A clear scope says what is included and who is responsible. ‘Refurbish the house’ leaves far more room for different interpretations than coordinated drawings, specifications and a properly described pricing document.
Specification
Written requirements for the quality, performance and workmanship of the project. It adds information that drawings alone cannot communicate reliably. If the required standard is unclear, builders may price different solutions even when they have received the same plans.
Schedule of Works (SoW)
An organised description of the work, read alongside the drawings and specification. It gives builders a common basis for pricing. Multiproject’s schedules include measured quantities and units, with rate and value columns for the builders to complete, together with section totals and a summary.
An SoW is not the construction programme: it describes what is to be done, rather than when. See our Schedule of Works guide and sample.
Bill of Quantities (BoQ)
A detailed document of measured work, descriptions and quantities, normally prepared using stated measurement rules. Contractors price its items to build up their tender. It serves a related purpose to an SoW, but the structure, measurement detail and contractual treatment can differ; quantities alone do not make a document a full BoQ.
The RICS New Rules of Measurement distinguish cost planning from detailed measurement.
Tender package
The coordinated information issued to contractors so they can prepare their offers. It can include drawings, specifications, an SoW or BoQ, programme requirements, proposed contract terms and instructions for returning prices. Gaps or contradictions in the package make reliable comparison harder.
Builder’s quote or quotation
A builder’s offer to carry out stated work for a stated price, subject to its terms, assumptions and exclusions. The label alone does not tell you how complete or reliable it is. Some builders quote without a separate charge; detailed estimating or pre-construction work may be chargeable.
Our comparison of quotes, cost plans and Schedules of Works explains when each is useful.
Tender
A contractor’s formal offer in response to an invitation and a defined package of information. It may include a price, programme and qualifications. A tender is useful evidence of what that contractor is offering; it still needs checking against the requested scope.
Tender qualifications
Conditions or reservations a contractor attaches to its offer, such as excluding work, assuming a particular access arrangement or allowing for a different specification. Here, ‘qualifications’ means limits on the offer, not professional credentials. Resolve their cost and scope implications before comparing prices or accepting a tender.
Tender clarifications
Questions and answers used to remove uncertainty in the tender information or a contractor’s offer. For example: does the price include making good after the structural work? During competitive tendering, information that changes the pricing basis should be issued consistently to the bidders. Record agreed clarifications in the final contract documents.
Tender analysis and like-for-like comparison
Reviewing offers for completeness, arithmetic, assumptions, exclusions, allowances, programme and other conditions. The aim is to understand the cost and substance of each offer on a comparable basis. Contractor suitability, resources and ability to deliver matter alongside the price.
Procurement route
The way the project’s design and construction services are organised, appointed and paid for. It affects when builders become involved, who carries design responsibility and how price and risk are dealt with. The right route depends on your project, priorities and the information available.
Traditional procurement and design and build
Under a traditional arrangement, the client generally appoints the designers and a contractor to build the design, although some specialist design may sit with the contractor. Under design and build, the contractor takes agreed responsibility for both design and construction. In either case, the contract needs to define the scope and responsibilities clearly.
Single-stage tendering
Inviting suitable contractors to price the whole defined project in one competitive tender exercise. Each receives the same coordinated information and pricing basis. It works best when the scope is sufficiently developed; incomplete information can produce assumptions and exclusions instead of comparable offers.
Two-stage tendering
Selecting a preferred contractor first, using criteria such as their team, approach and agreed pricing components, then working with them to develop the information and final price. It can bring useful contractor input earlier. Selection at stage one does not mean the full construction price is settled.
Negotiated tender
Developing and agreeing a price with one selected contractor rather than running a full competitive tender exercise. It can suit some projects and established relationships. You still need a clear scope, a transparent price breakdown and a way to assess whether the offer represents value.
These approaches are explained in the RICS guidance on tendering strategies.
Pre-Construction Services Agreement (PCSA)
An agreement appointing a contractor to provide defined services before the main building contract, often during two-stage tendering. These might include advice on buildability, programme and pricing. Agree the fee, outputs, responsibilities and what happens if the main contract is not agreed. Early involvement should have a clear purpose and agreed deliverables.
JCT (Joint Contracts Tribunal)
The organisation that publishes a range of standard construction contracts and related documents. ‘A JCT contract’ does not identify one set of terms: the form, edition, completed particulars and amendments all matter. Choose a contract that fits the work, design responsibilities and way the project will be managed.
The JCT contract range includes forms for different project arrangements.
Fixed price and contract sum
The contract sum is the agreed starting price under the building contract. ‘Fixed price’ usually relates to defined work on stated terms; it does not automatically include later scope changes, unresolved allowances or every possible risk. Read the scope and adjustment provisions before treating the figure as your final spend.
People, responsibilities and project management
Client or employer
The person or organisation commissioning the work. On a home project, that will usually be you; ‘employer’ is a common term in building contracts. Your role includes setting priorities, making decisions, appointing suitable support and providing funds in accordance with your agreements.
Quantity surveyor (QS)
A professional concerned with construction costs and the commercial aspects of a project. Depending on the appointment, a QS can prepare cost plans and pricing documents, assess tenders, value changes, report costs and help agree the final account. A one-off cost plan does not automatically include ongoing project support.
Architect and design team
The people developing and coordinating the design, which may include an architect, structural engineer and other specialists. Their services and responsibilities should be agreed in writing. Do not assume that design, site inspections, project management and contract administration are all included in one appointment.
RIBA (Royal Institute of British Architects)
A professional body for architects, which publishes guidance including the RIBA Plan of Work. You may encounter the name when discussing an architect’s membership, practice status or project stages. Membership and a stage label do not define your appointment: agree the services, deliverables and responsibilities in writing.
Learn more about RIBA.
RICS (Royal Institution of Chartered Surveyors)
A professional body that sets standards and qualifications and regulates its members and regulated firms. Its guidance includes cost planning and measurement. ‘Quantity surveyor’ describes a role; it does not by itself confirm RICS membership or a firm’s regulated status. Check the specific credentials and relevant experience of the people you appoint.
Learn more about RICS.
Project manager
The person coordinating delivery against the agreed objectives, including decisions, responsibilities, information and programme. The scope varies between appointments. A project manager is not automatically the designer, quantity surveyor or contract administrator, even where one person performs several roles.
Contract administrator (CA)
The person appointed to administer the building contract where that contract provides for the role. Duties may include issuing instructions, assessing payments and certifying completion. The role carries specific contractual responsibilities, so it should be clearly appointed rather than assumed to sit with whoever attends site meetings.
Main contractor and subcontractor
The main contractor has the building contract with the client and manages delivery of the agreed work. A subcontractor is appointed by a contractor to carry out part of it. If you appoint trades directly, the contractual relationships and coordination responsibilities are different and need to be planned.
CDM (Construction Design and Management Regulations)
The CDM 2015 regulations organise health and safety responsibilities on construction projects in Great Britain, including domestic work. Special arrangements apply to domestic client duties. Discuss who will perform the relevant roles and provide the required information before work starts, rather than assuming a small home project falls outside the rules.
The HSE guide to CDM responsibilities explains the roles.
Principal designer and principal contractor
Under CDM, these roles coordinate health and safety during the pre-construction and construction phases respectively on projects involving more than one contractor. In England, building regulations also use these titles for separate duties concerned with compliance. One organisation may perform both versions of a role if competent, but the responsibilities and appointments must be clear.
Programme and critical path
The programme sets out the sequence and timing of activities and decisions. The critical path identifies activities whose delay would delay the project’s completion, based on the programme’s logic. Your selections, approvals and information can affect progress just as much as work on site.
Change control
A process for recording, assessing and authorising changes. Before committing, understand the effect on scope, cost, time and other work, then record the decision and update the project information. Several individually modest changes can add up to a significant movement in the budget.
Cost report and forecast final cost
A cost report brings together the current financial position: agreed costs, changes, allowances, risks and what remains to be resolved. The forecast final cost is the best current assessment of where the project will finish, on a clearly stated basis. Money paid so far is only one part of that picture.
Read more about cost control for small projects.
Changes, payments and completion
Variation
A change to the work dealt with under the building contract, such as an addition, omission or altered requirement. The contract determines how it is instructed and valued. Understand the likely cost and time effect before agreeing the change wherever possible.
Interim valuation and payment certificate
An interim valuation assesses the value of work and any other items payable at a point during the project. A payment certificate, where the contract provides for one, records an amount certified under that process. These are different from simply receiving an invoice; use the payment procedure and dates in your contract.
Retention
An amount withheld from payments where the contract provides for it, with release linked to specified conditions or milestones. The percentage, timing and procedure need to be agreed. Retention is not a substitute for choosing a suitable contractor, inspecting the work or managing defects.
Extension of time
An adjustment to the contractual completion date where the contract allows it. The cause of delay, notice requirements and supporting records matter. An entitlement to more time and an entitlement to additional money are separate questions; neither should be assumed from the other.
Practical completion
A contractual milestone recognising that the work has reached the required state of completion. It can trigger handover, payment and other consequences. The test depends on the contract and circumstances; it is not simply the day you move in or the builder removes their tools.
Snagging
Inspecting and recording defects or outstanding items so they can be addressed. A snagging list needs clear descriptions, responsibility and follow-up. Calling something a snag does not settle whether it is minor or whether practical completion should be certified.
Handover
The transfer of the completed project to the client, including keys, operating information, relevant certificates, warranties and an explanation of how the building’s systems work. Agree the required documents and arrangements early, so they are ready when you need them.
Rectification period or defects liability period
A period provided for in many contracts after practical completion, during which notified defects are dealt with through the contract’s procedures. Check its length, reporting process and the arrangements for access. The end of that period does not automatically end every possible responsibility for defective work.
The RICS guidance on defects and rectifications explains the wider distinctions.
Final account
The final calculation and agreement of the amount due under the building contract, taking account of adjustments such as variations and provisional sums. It is distinct from the whole project’s final cost, which may also include fees and items you bought directly. Good records throughout the project make this process easier.
Put the terms to work on your project
The useful question is not just ‘what does this word mean?’ It is ‘what does this document or allowance actually cover on my project?’ Ask for the scope, the basis of the figure and who owns the next decision. Clear answers make it easier to choose where to spend and what to do next.
If you are developing a design or preparing to approach builders, explore our cost planning support for homeowners, or talk to us about your project. We can help you work out what information you need at your current stage.
