How to choose a loft conversion company

Follow the same process with every company you consider:

1. Identify suitable firms and check their comparable loft experience.
2. Ask about availability, services and current project capacity.
3. Give shortlisted companies the same drawings, specification and project information.
4. Obtain at least three detailed written quotes where practical.
5. Verify preferred candidates and compare scope, exclusions and total payable.
6. Record responsibilities, payments and variation procedures in the final contract.

You can make early enquiries before drawings exist. Ask about feasibility, services and an indicative budget at this stage.

Treat early figures as guidance, not comparable construction quotes. Detailed quotes need a sufficiently defined design, scope and finish level.

Design-and-build companies may initially propose different solutions. Align those proposals before comparing their prices.

Loft conversion company checklist

Use this checklist for every company on your shortlist:

• The company has completed a similar loft conversion recently.
• Legal, trading, insurance and payment names have a documented connection.
• Recent customers have confirmed costs, communication and snagging standards.
• Insurance documents remain valid for the proposed work and dates.
• The quote follows your drawings, specification and finish requirements.
• Allowances, exclusions, VAT and possible price changes appear clearly.
• A named person will manage the site and communicate progress.
• Design, approval and inspection responsibilities appear in writing.
• Payment stages correspond with identifiable completed work.
• The contract explains delays, variations, handover and defects.

Download the six-page loft conversion company comparison checklist PDF.

On this page

• Shortlisting companies
• Checking a company
• Questions to ask
• Comparing quotes
• Warning signs
• Appointing the company

How to shortlist loft conversion companies

Shortlist two or three companies with recent, comparable loft experience. General ratings matter less when reviewers describe unrelated kitchens or small repairs.

Look for similar properties, roof structures and conversion designs. A company should also understand occupied homes, access constraints and local approval routes.

Ask about availability before investing time in detailed meetings. A strong company may still be unsuitable if its manager lacks capacity.

Early communication also provides useful evidence. Clear questions and written follow-ups usually indicate a more organised working process.

What counts as relevant loft conversion experience?

Relevant experience closely matches the challenges within your proposed conversion. Compare these points against each company's recent work:

• Property type, including terraced, semi-detached, detached or bungalow construction
• Conversion design, such as rooflight, dormer, hip-to-gable or mansard
• Structural complexity, including steelwork and substantial roof alterations
• Staircase position and the required fire-safety improvements
• Restricted access, shared routes or party-wall requirements
• Bathroom drainage, water pressure and heating requirements
• Planning restrictions or sensitive external design details

A recent dormer on a similar terrace provides strong practical evidence. Several unrelated extensions do not prove the same roof-building experience.

Ask what proved difficult and how the team responded. Detailed answers reveal more than polished photographs of the finished room.

Loft conversion specialist or general builder?

No appointment model works best for every project. The written responsibilities matter more than the label used by the company.

A specialist may offer an efficient established process. Check how its standard package accommodates unusual structures or bespoke finishes.

A general builder may coordinate work elsewhere in the house. Check whether its loft team has current, relevant roof experience.

How to check a loft conversion company

Check the company behind the quotation, not only its trading name. Reviews cannot identify who accepts contractual responsibility or receives your money.

Use several forms of evidence together. Registered details, recent work, customer references and insurance each answer different questions.

Verify the business you will contract with

Confirm the full legal name and trading name before comparing documents. Sole traders will not have a Companies House registration number.

For registered companies, check the following information:

• Company number, active status and registered address
• Incorporation date and current filing history
• Overdue filings, strike-off action or insolvency information shown
• Documented connections between names on contracts, insurance and payment details
• Signing authority for the person issuing the contract
• Trading history of the current contracting business

Companies House provides registered details and filed documents. It does not verify workmanship, competence, solvency or future financial stability.

A long-running brand may trade through a newer legal company. Sole traders and group policies can also use different names.

Ask for documents connecting every relevant name to the contracting party. If bank details change, confirm them through an established contact method.

The contract should identify who accepts responsibility and who receives payment. Never rely on an unexpected email containing replacement bank details.

Check recent loft conversion work

Ask for one completed conversion that closely resembles your project. Also request a recent project, not only the company's favourite historical example.

A current site visit can show organisation and work in progress. The homeowner and site manager must agree before any visit takes place.

Ask to see construction-stage photographs alongside finished images. Useful records can support a detailed discussion about concealed work.

Photographs cannot prove correct design, installation or inspection. Cross-check important claims against drawings, calculations and inspection records.

Discuss the original scope and any later changes. This shows how the company handles surprises, variations and client decisions.

Confirm that the contracting company completed the stated project. Photos alone do not establish which business managed or delivered the work.

Speak to previous customers

References work best when you ask factual, open questions. Speak directly with customers who have agreed to be contacted.

Ask whether the final cost stayed close to the accepted quote. Then ask which changes or hidden conditions increased the price.

Confirm whether the company priced extras before starting them. Also ask who managed the site and communicated delays.

Occupied-home projects require sensible security, access and daily tidiness. Ask how the team managed these issues during construction.

Finally, ask how the company handled snagging and later defects. A useful reference should explain whether they would appoint the company again.

Check insurance, memberships and trade qualifications

Request current insurance schedules before accepting the company's offer. Check the policyholder, insured activities, cover limits and expiry dates.

Public liability insurance covers certain claims involving injury or property damage. Employers' liability insurance applies where the business employs people within its scope.

Contract works or project insurance may cover the developing works. Your home insurer may impose separate conditions before construction starts.

Where the company supplies design services, ask about professional indemnity cover. This may support claims involving covered design errors.

Verify trade-association memberships directly with the named organisation. Membership badges alone provide weak evidence and may be outdated.

Confirm registrations for electrical, gas and other specialist work. Ask how the main company checks subcontractor competence and insurance.

Read every written warranty or guarantee before treating it as valuable. Check its provider, exclusions, duration and claim procedure.

A commercial guarantee supplements your consumer rights rather than replacing them. Missing or weak terms require clarification, not automatic rejection.

Our loft conversion insurance guide explains cover before and during construction.

Questions to ask a loft conversion company

Ask every shortlisted company the same core questions. Comparable answers expose gaps before companies prepare their quotations.

Ask for documents supporting important claims. Examples include insurance schedules, registrations and a proposed contract.

Who will design and manage the conversion?

Establish who takes responsibility for each design and compliance task. This includes architectural drawings, structural calculations and coordination between consultants.

Record who checks whether the proposal qualifies as permitted development. Also identify who applies for a lawful development certificate where appropriate.

If permission is required, record who submits the planning application. Confirm who prepares the Building Regulations design and books Building Control inspections.

The responsibility schedule should also cover design changes during construction. Include party-wall matters where they affect the proposed work.

Ask who holds the principal designer and principal contractor roles. Identify whether each appointment covers CDM, Building Regulations or both.

Under CDM 2015, domestic-client duties normally pass to the sole contractor. Projects involving several contractors normally require a principal contractor.

A principal designer can accept those domestic-client duties through written agreement. HSE guidance explains the position.

A subcontractor counts as a contractor for this assessment. One homeowner contract can therefore still involve several contractors on site.

Separate Building Regulations dutyholder rules apply in England. Similar role titles carry different functions under each regime.

Confirm each appointment in writing and check the appointed party's competence. CDM 2015 applies across Great Britain, while approval systems differ elsewhere in the UK.

Who will actually work on site?

Ask whether employees, subcontractors or both will complete the work. Subcontracting is common, but supervision must remain clear.

Confirm who opens the property and secures it each evening. A named manager or documented team should coordinate the trades.

Ask how many concurrent projects that manager oversees. A crowded programme can reduce site attendance and slow decisions.

Ask who provides your regular contact and approves site decisions. Record who provides cover when that person becomes unavailable.

Occupied homes need controlled access and temporary protection. Ask about safe routes, welfare arrangements and preventing unauthorised entry.

How will delays and unexpected work be handled?

Hidden structural conditions can appear after opening the existing roof. The contract should explain investigation, pricing and approval before extra work proceeds.

Use the same process for material substitutions and design revisions. Record both the cost and effect on the completion date.

Weather can delay roof work despite reasonable precautions. Ask how the company updates its programme and protects exposed areas.

Agree planned variations in writing before the changed work begins. Record its scope, price and effect on completion.

The contract should also cover urgent work needed for safety. Require prompt notification, reasons, photographs and cost records.

Our loft conversion timeline guide explains the stages and common programme pressures.

How to compare loft conversion quotes

Compare quotations only after each company prices a sufficiently defined scope. Different drawings or finish assumptions make headline totals unreliable.

Issue identical drawings, specifications and bathroom requirements. Include window choices, staircase details, access limits and intended start periods.

Also provide a responsibility schedule covering design, approvals and inspections. Obtain three comparable written quotations where practical.

What should a loft conversion quote include?

First, check whether the document is a quotation or estimate. An estimate gives an expected cost rather than an agreed figure.

A quotation normally commits the trader to an agreed price for defined work. Extra charges need a proper contractual basis, such as agreed additional work.

The trader cannot simply raise an accepted quote because its costs increased. Citizens Advice explains the distinction.

Acceptance can create a contract without a signature. Complete your checks before accepting the quotation or authorising work.

Even a fixed price needs a clear scope and adjustment rules. Check its validity period and assumptions before acceptance.

A detailed quotation should address these project areas:

• Surveys, architectural drawings and included design revisions
• Planning work, structural calculations and Building Regulations design
• Building Control fees, inspections and completion documentation
• Party-wall services and related project responsibilities
• Scaffolding, included hire and temporary weather protection
• Additional scaffold hire and responsibility for project delays
• Structural steelwork, floor construction and roof alterations
• Roof coverings, cladding, windows and rooflights
• Staircase, guarding, balustrades and affected lower-floor finishes
• Insulation, fire protection and required escape-route improvements
• Plumbing, heating, electrical work and bathroom installation
• Plastering, joinery, decoration, flooring and agreed finishes
• Protection of the existing property and occupied areas
• Working hours, access assumptions and site security
• Waste removal, final cleaning and making good
• Proposed start date, programme and expected site attendance
• Handover records, warranties, snagging and defect arrangements
• VAT treatment and the total amount payable

Use our loft conversion cost guide for national budgeting information. Keep those guide figures separate from your project quotations.

Allowances, provisional sums and exclusions

An allowance is not a fixed final cost. It assigns an amount until the actual product or work becomes known.

Provisional sums often cover work that lacks enough detail for firm pricing. Ask what information will replace each provisional figure.

An exclusion transfers the cost or responsibility elsewhere. Add every excluded essential item to your separate project budget.

The phrase "by client" also needs a realistic allowance. It may include purchasing, delivery, installation or coordination responsibilities.

"Not stated" means unknown, not zero. Request written clarification instead of assuming the company has included an item.

Compare VAT consistently across every quote. The figure that matters is the total amount you will pay.

Include the promises and specifications you relied upon in the written offer. Record any later agreed change clearly.

Broad rights to adjust a fixed price need clear limits. Consumer contracts must remain fair and transparent.

Example comparison of quotation scope

The lower headline price cannot yet be compared fairly with the higher offer. Missing information may change the final payable amount.

Price every missing essential item before choosing between the offers. Do not fill unknowns with general national averages.

Loft conversion company red flags

A warning sign does not automatically prove poor practice. It gives you a reason to request evidence or clearer written terms.

Take extra care when you find any of these issues:

• Different names lack a documented connection to the contracting business.
• Payment goes to an unrelated person or unverified account.
• The company encourages cash-only or unrecorded payments.
• No written specification defines the proposed conversion.
• The company cannot provide comparable recent work or references.
• Insurance, membership or qualification claims cannot be verified.
• No manager or documented team accepts site responsibility.
• Important promises remain absent from the written agreement.
• Broad allowances form a large part of the quotation.
• A fixed quote permits wide, poorly defined price increases.
• The company cannot explain an unusually low total.
• Work starts before approvals and responsibilities become clear.
• The programme conflicts with the company's other active projects.
• No written process controls design or cost changes.
• Commercial warranty terms remain unavailable or unclear after enquiries.
• The company pressures you to decide or pay immediately.
• Representatives repeatedly miss calls, visits or agreed commitments.

One missing document may have a straightforward explanation. Several unresolved issues create a much weaker basis for appointment.

How to appoint a loft conversion company

Appoint the company whose evidence and written offer best fit your project. Price matters, but unclear scope creates expensive uncertainty later.

Complete your checks before accepting an offer, authorising work or paying a deposit. A signed document is not the only way to form a contract.

Include the promises and specifications you relied upon in the final agreement. Clearly record any changes that both parties later accept.

Information you relied upon can become a contract term. Section 50 of the Consumer Rights Act explains this protection.

How to make the final decision

Use a decision sheet to compare each company consistently. Record evidence and unresolved concerns, not only personal impressions.

Compare these areas:

• Relevant experience and the supporting projects supplied
• Business, insurance and qualification evidence
• Feedback from recent comparable customers
• Completeness of scope and quotation detail
• Allowances, exclusions and total including VAT
• Site management and communication arrangements
• Contract terms, programme and payment structure
• Remaining design, approval or delivery risks

Use scores cautiously and keep unresolved concerns visible. A low price does not remove unclear scope or unresolved risk.

Write one short reason for choosing your preferred company. This brings the evidence, price and risks into one decision.

Put the complete scope into the contract

The contract should identify the legal parties and agreed documents. Attach the final drawings, specification, quotation and responsibility schedule.

Record responsibility for design, structural calculations, approvals and inspections. Name the site manager and relevant dutyholders.

Cover property protection, security and temporary weather protection. Include neighbour access, shared routes and waste removal where relevant.

The contract should address damage caused during construction. It should also state the start date, programme and delay procedure.

Define payment stages, variations, snagging and defect responsibilities. Record any commercial warranty or guarantee terms.

Those guarantees supplement the company's consumer-law duties. Services must still be performed with reasonable care and skill.

Record who completes compliant work, coordinates inspections and supplies supporting evidence. Also state who addresses defects identified during inspections.

A builder cannot guarantee that Building Control will issue completion documentation. The decision remains with the relevant building control body.

Consumer contracts must use fair and transparent terms. CMA guidance explains that requirement.

Check cancellation rights before paying a deposit

Cancellation rights depend on where and how you make the agreement. Distance or off-premises contracts may provide a statutory cancellation period.

Ask for the applicable cancellation information before accepting the offer. Do not assume every building contract carries an unconditional 14-day right.

Starting during a cancellation period can affect what you owe. Understand the consequences before requesting an early start in writing.

The Consumer Contracts Regulations explain these rights. Seek independent advice when the position remains unclear.

Agree payments and variations

Ask what any deposit covers and when it becomes payable. Check when it can be retained and how cancellation charges are calculated.

Blanket non-refundable terms may be unfair. Deductions should reflect the contract, applicable rights and legitimate costs.

Link later payments to identifiable completed work. Dates alone provide weaker protection when the programme changes.

Use written invoices and traceable payment records. Every receiving account needs a documented connection to the contracting party.

Confirm changed bank details independently using a known telephone number. Do not rely solely on the message announcing the change.

Planned additional work needs a described and priced variation. Record its cost and effect on the completion date together.

The contract should allow necessary emergency action to protect the property. Require prompt notice and supporting records afterwards.

Agree how final payment relates to completion and snagging. The contract should also explain disputed work or invoices.

No single deposit or retention percentage suits every loft conversion. The payment structure should reflect real expenditure and completed progress.

Confirm the handover documents

Agree the handover list before construction starts. This makes document responsibilities easier to manage throughout the build.

Depending on the work and approval route, your project may require:

• Building Control completion documentation
• Electrical and gas certificates where applicable
• Window, rooflight or product documents where applicable
• Written warranties and guarantees
• Structural and design information
• Equipment operating instructions
• Final drawings where the appointment includes them
• Agreed snagging record and completion status
• Named defects contact and response procedure

Product documents do not replace Building Control evidence. Store every record with the contract and payment information.

Our step-by-step loft conversion guide shows where these checks fit within the wider project.