What Should a House Extension Quote Include?

A good house extension quote should tell you what the builder will build, what the price includes and what you will need to arrange separately. You should be able to read it alongside your drawings and understand the finish you can expect at handover. That matters when comparing builders in Wakefield, Leeds or elsewhere in West Yorkshire. Two prices for the same-sized extension can cover different amounts of work. One might include the doors, heating and plastering, while another stops at the building shell. At CG Building Services, we want customers to understand the work our price covers. These are the details to check before you choose a builder.

Start with the drawings and the agreed scope

Start by checking the property address and extension details. The quote should also identify which drawings the builder used. If your plans have changed, make sure everyone is working from the latest version. The description should distinguish the new extension from alterations inside your existing house. A new room, a knock-through, moving a kitchen and converting a garage are separate pieces of work, even when they form one project. Ask where the work starts and finishes. Does removing a wall include repairing the adjoining ceiling, moving sockets and making good the floor? Clear boundaries make the price easier to understand.

Check the main building work

A clear house extension quote should describe the main parts of the build. Look for:

• • Site preparation, demolition, skips and removal of waste.

• • Foundations and any stated assumptions about ground conditions.

• • Drainage work and connections for rainwater.

• • External walls, insulation and the agreed brick or render finish.

• • Floor construction, damp protection and insulation.

• • Roof structure, covering, insulation, flashings and rainwater goods.

• • Structural openings, beams and their installation where required.

• • Plasterboarding, plastering and making good.

Pay particular attention to the roof description. A tiled roof and a flat roof need different specifications, so the quote should name the roof covering. It should also identify any rooflights or lantern. If your project needs structural calculations, establish who pays the engineer. Then check whether the builder has allowed for the steelwork and its installation. Our guide to structural engineers for house extensions explains how that design work fits into the project.

Make windows and doors specific

“Doors included” leaves several questions unanswered. Check the approximate sizes, materials, colour and opening arrangement. Aluminium sliding doors, bi-folds and uPVC French doors are different products with different fitting requirements. Establish whether the price covers supply, fitting, glazing, sealing and local making good. If you are buying the doors yourself, agree who checks the opening sizes and coordinates delivery. The quote should clearly identify any glazing allowance. Before ordering, confirm whether your chosen specification fits that allowance and agree any price difference.

Count the electrical points and heating provision

Electrical work needs enough detail to match how you intend to use the room. Check the number of double sockets, ceiling lights, switches and outside lights. Find out who supplies the light fittings. Some prices only cover wiring and installation. A kitchen extension may also need connections for appliances, an extractor, under-unit lighting or an island. Give the builder and electrician your kitchen layout before they finalise these details. For heating, check the number and type of radiators, or the proposed underfloor heating. The price should explain whether it covers valves, pipework and connection. Your plumber can also assess whether the existing system needs an upgrade. These checks help turn a general description into a room you can actually use.

Understand the finishing point and exclusions

A plastered extension still needs finishing. Clarify responsibility for decorating, final flooring, skirting, internal doors and any kitchen or bathroom installation. “Customer to supply” and “excluded” mean different things. You might purchase a sink while the builder’s price includes fitting it. Alternatively, both supply and installation might sit outside the quotation. Check professional and application fees too. Agree who arranges and pays for the design drawings, structural calculations and Building Control charges. Our article on Building Control inspections during an extension explains the inspection stages.

Distinguish a quote from an estimate

An estimate is an approximate guide. A quotation sets a price for the stated work, so read the scope, exclusions and any provisional allowances together. Citizens Advice explains the distinction and recommends obtaining written quotes before choosing a trader. A provisional allowance means the builder has not yet confirmed a particular cost. Ask what the allowance covers and how the builder will confirm it. Does that figure cover both labour and VAT? Agree a process for changes too. If you choose a different door system or request additional work, agree the revised scope, price and any timing implications in writing before that work proceeds.

Check the total and payment arrangements

The quote should clearly show whether the total includes VAT. Confirm how long the quote remains valid and identify any optional extras outside that total. Agree when payments are due and what happens at completion. At CG Building Services, we do not take a deposit. Our customers pay weekly as work progresses. They keep a small final retention until we complete the work and receive the relevant Building Control sign-off. The agreed quotation sets out these arrangements. Discuss the proposed start date and likely build duration as well. Ask how material lead times, inspections and changes to the work could affect the programme.

Compare the same work across each quote

When comparing a house extension quote, put the scope descriptions side by side. Mark each item as included, excluded or needing clarification. For example, one builder might price the shell and plastering. Another might also cover glazing, electrical work, heating and kitchen fitting. Those totals cover different jobs. Ask for the missing information before deciding which offers the best value. Keep the final drawings, quotation and agreed changes together. That gives you and the builder a shared record to refer to throughout the project.

Planning an extension in Wakefield or Leeds

CG Building Services builds house extensions across Wakefield, Leeds and surrounding parts of West Yorkshire. If you have drawings or are still working through your ideas, we can discuss the proposed work and explain what our quotation covers. Ask about anything that is unclear before you commit. Get a free quote from CG Building Services today, call 07837 801106, or email info@greenfieldbuildingservices.co.uk.