Renovation Tender Questions to Ask Before You Hire a Builder

If you are planning a major home improvement, asking the right renovation tender questions before you hire a builder can save you thousands of pounds, weeks of stress, and a lot of avoidable disruption. A typical example we see across the UK is a rear extension quoted at £45,000 that ends up costing £60,000 once missing items, underestimated allowances, and poorly defined work are added back in. Most of that overspend can be traced back to a weak or unclear tender.

A tender is more than just a price. It is a detailed snapshot of how a contractor plans to deliver your project, including costs, timelines, materials, and responsibilities.

Many homeowners focus on the bottom line and miss the detail that sits behind it. That is where problems begin. As someone who has worked on residential builds and refurbishments across the UK, I have seen disputes arise not from bad workmanship, but from unclear expectations at tender stage.

This guide walks through the questions you should be asking every builder before you commit. It reflects real industry practice, current UK standards, and the common pitfalls that catch homeowners out.

Why renovation tenders matter more than the price

Not all quotes include the same level of detail

A tender is your first proper insight into how organised and transparent a builder is. Two quotes can look similar in total cost but differ wildly in scope, quality, and risk.

For example, one builder might include full electrical certification and upgraded consumer units to meet current BS 7671 wiring regulations, while another assumes the existing system is adequate. That difference alone could mean an extra £1,500 to £3,000 later.

Similarly, structural work might or might not include calculations by a structural engineer, which are typically required for Building Control approval and can cost £400 to £1,200 depending on complexity.

Labour and material assumptions vary significantly

Across the UK, skilled labour rates vary but typical daily rates are:

• General builder, £180 to £250 per day
• Electrician, £250 to £350 per day
• Plumber, £220 to £320 per day
• Carpenter or joiner, £200 to £300 per day

If a tender is significantly cheaper, it may assume fewer labour days, lower grade materials, or cuts to scope. For instance, installing structural steel beams, often required for open plan layouts, typically costs £1,500 to £3,500 including supply, installation, and making good. If that is missing or underpriced, it will surface later.

Cheap tenders often shift risk onto you

Builders sometimes keep initial prices low by loading the quote with provisional sums or vague assumptions. This transfers cost risk onto the homeowner. It is one of the most common causes of disputes.

That is why your job is not simply to compare numbers, but to interrogate what sits behind them.

Key renovation tender questions

1. What exactly is included in this price?

This sounds obvious, but it is the most overlooked question.

Ask the builder to break down the tender into clear sections:

• Demolition and strip out
• Groundworks or structural work
• Materials and labour
• Fixtures and fittings
• Finishing work such as plastering and decorating
• Waste removal and skips

In UK renovation projects, skips alone can cost £250 to £450 each depending on size and location. If that is not included, it will be added later.

A good answer from a builder will include quantities, for example how many skips, how many square metres of plastering, and what specification of materials.

If you are unsure how to assess a quote in detail, this guide is worth reviewing: What to check on your builder quote.

2. What is excluded or assumed?

This is where experienced homeowners gain an edge.

Ask directly what the builder has not included. Common exclusions include:

• Planning permission fees, typically £206 for householder applications in England
• Building Control fees, usually £300 to £900 depending on project scope
• Kitchen supply or bathroom suites
• Floor coverings
• Upgrade works triggered by building control inspections

Ambiguity here is one of the main causes of cost overruns. A professional builder will list exclusions clearly rather than burying them in small print.

3. Are your figures fixed or provisional?

Most tenders contain provisional sums or prime cost items. These are allowances rather than fixed prices.

Examples might include:

• £3,000 allowed for a kitchen, which may realistically cost £6,000 to £12,000
• £1,500 for bathroom fittings, which may not cover your preferences

Ask how many provisional sums are included and whether they can be firmed up before work begins. The fewer unknowns, the lower your risk.

4. What is your timeline and availability?

A credible builder should offer a clear programme of works, even if it is high level.

Typical timelines in the UK:

• Single storey rear extension, 10 to 16 weeks
• Loft conversion, 8 to 12 weeks
• Full house renovation, 4 to 8 months

Ask:

• Start date and completion estimate
• Whether they are working on other jobs at the same time
• How delays are handled

Example renovation timeline

For a typical 12 week rear extension, a realistic sequence might look like:

• Weeks 1 to 2, site setup, demolition, and groundworks
• Weeks 3 to 5, foundations, drainage, and structural walls
• Weeks 6 to 7, roof structure and watertight shell
• Weeks 8 to 9, first fix electrics and plumbing
• Weeks 10 to 11, plastering, second fix, and kitchen installation
• Week 12, finishing, snagging, and Building Control sign off

If a builder cannot explain their plan at this level, it usually means the job is not fully thought through.

5. Who will actually be on site?

Some companies price and sell the job but subcontract most of the work.

That is not inherently a problem, but you need clarity on:

• Who your day to day contact is
• Whether trades are in house or subcontracted
• How quality is supervised

Consistent site management is critical for quality control and health and safety.

6. Are you insured and certified?

Any builder working on your property should have:

• Public liability insurance, typically £2 million cover minimum
• Employer's liability insurance if they have staff
• Relevant trade accreditations

For specialist trades:

• Electrical work should comply with NICEIC or equivalent schemes, which confirms competence under Part P
• Gas work must be carried out by a registered Gas Safe engineer

For larger projects or new builds, check whether work is covered by an NHBC warranty or similar structural warranty provider.

Ask for proof. Do not take verbal assurances.

7. How will you handle Building Regulations compliance?

Most renovation work falls under Building Regulations, even if planning permission is not required.

Relevant parts include:

• Part A, structure and load bearing elements
• Part P, electrical safety
• Part L, energy efficiency including insulation and glazing

Builders should explain:

• Whether they will liaise with Building Control
• How inspections will be scheduled at key stages such as foundations and structural work
• Who is responsible for certification and final sign off

You can read official guidance here: https://www.gov.uk/building-regulations-approval.

Failure to obtain Building Control approval can create serious issues when selling your home.

8. What is your payment schedule?

A standard arrangement in UK residential work involves staged payments.

Typical structure:

• Deposit, 5 to 10 percent
• Stage payments tied to milestones such as completion of foundations or roof
• Final payment after completion and snagging

A builder asking for 50 percent upfront should raise concern.

Make sure payment stages align with visible progress, not vague time periods.

9. How do you manage changes or variations?

Changes are almost inevitable. The key is how they are documented and priced.

Ask the builder:

• How variations are quoted
• Whether written approval is required
• How costs are tracked

Variation costs are usually priced based on labour, materials, and margin. For example, moving a socket might cost £80 to £150, while structural changes could run into thousands. Always get a written quote before approving changes.

Verbal agreements lead to disputes later.

10. Can you provide recent references or live projects?

Any reputable builder should be able to show recent work.

If possible, visit an active site. You will learn more in 15 minutes than from any brochure:

• Is the site tidy and safe?
• How do trades interact?
• Is the work organised?

For a broader approach to vetting, see Builder Vetting Checklist Before Hiring a Renovation Contractor.

Comparing builder tenders properly

Use structure rather than instinct

Use a structured approach rather than relying on instinct.

Criteria	Builder A	Builder B	Builder C
Total cost	£48,000	£52,000	£45,000
Provisional sums	Low	Medium	High
Timeline	12 weeks	16 weeks	Unclear
Insurance and accreditations	Yes	Yes	Unverified
References	Strong	Good	Limited

Here is how to interpret this in practice. A lower total cost paired with high provisional sums usually means the price will increase later. An unclear timeline often signals poor planning or overbooking. Missing or unverified insurance should be treated as a serious risk. Strong references and clear documentation often justify a slightly higher price because they reduce uncertainty.

Understanding cost types in tenders

Type	Definition	Risk level	Example
Fixed cost	Agreed price for defined work	Low	£4,000 for plastering entire extension
Provisional sum	Estimate for work not fully defined	Medium to high	£2,000 for drainage adjustments
Prime cost item	Allowance for supply only items	Medium	£1,500 allowance for bathroom suite

The more fixed costs you have, the more predictable your budget will be. High provisional sums should prompt follow up questions.

Common mistakes homeowners make during tender stage

Choosing based on price alone

This remains the biggest error. If one quote is significantly lower, there is usually a reason. Missing items, unrealistic allowances, or miscalculations.

A £10,000 difference on a £50,000 job is rarely due to efficiency alone. It usually means something is not included.

Providing unclear project details

If builders are pricing from vague information, their tenders will vary wildly.

Provide:

• Detailed drawings where possible
• A written scope of works
• Clear expectations on finishes such as flooring type or kitchen specification

The clearer your brief, the more accurate your tenders will be.

Not formalising the agreement

A tender is not a contract. You still need a proper agreement that sets out responsibilities, payment terms, and dispute resolution.

Many UK homeowners use a JCT Home Owner Contract. These typically cost £30 to £100 and provide a recognised legal framework covering payment stages, delays, and variations.

This resource explains what should be included: What to Include in Your Builder Agreement.

Ignoring communication style

If communication is poor before the job starts, it will not improve during the build.

You can improve this aspect by setting expectations early, as outlined here: How to Choose and Work with Your Contractor.

Not planning for contingency

Even with a strong tender, unexpected issues arise. Hidden structural defects, outdated wiring, or drainage problems are common in older UK homes.

Set aside 10 to 15 percent of your total budget for contingency. On a £60,000 project, that is £6,000 to £9,000.

What can go wrong if you skip proper tender checks

Budget overruns and disputes

Renovation projects have a lot of moving parts. Weak tender scrutiny leads to predictable problems:

• Budget blowouts due to missing items
• Delays caused by poor planning or overbooking
• Disputes over what was agreed
• Non compliant work requiring costly corrections

In worst cases, homeowners end up paying twice, once to fix problems left by the first contractor.

Compliance and legal issues

Failure to follow Building Regulations can result in enforcement action or difficulty selling your home. For example, missing Part P electrical certification can delay a sale or require retrospective approval.

The Health and Safety Executive also highlights the legal responsibilities homeowners share when hiring contractors. As a domestic client, you still have duties under CDM regulations, even if these are often transferred to your contractor. You can review guidance here: https://www.hse.gov.uk/construction/cdm/2015/domestic-clients.htm.

Planning permission misunderstandings

Some projects fall under permitted development, but others require formal approval.

Typical rules include:

• Rear extensions within certain size limits may not need planning permission
• Loft conversions often fall under permitted development if within volume limits
• Flats and listed buildings almost always require permission

Approval timelines are usually 8 weeks for standard applications. You can check requirements here: https://www.planningportal.co.uk/.

Red flags in a tender

• Vague or one page quotes with little detail
• High number of provisional sums
• Missing insurance information
• No clear timeline or programme
• Reluctance to provide references
• Large upfront payment requests

Practical tender checklist

Before accepting any builder's quote, run through this:

• Detailed scope of works provided and understood, this ensures both parties are pricing the same job
• Clear breakdown of costs and materials, helping you compare like for like
• Minimal provisional sums, reducing financial uncertainty
• Timeline agreed with key milestones, allowing you to plan around the work
• Insurance documents checked, protecting you from liability
• Relevant certifications verified, ensuring compliance with regulations
• Payment schedule tied to progress, avoiding overpayment
• Process for variations agreed, preventing disputes later
• References or site visits completed, confirming track record
• Contract terms reviewed and signed, giving legal protection

If any of these are missing, resolve them before work begins.

FAQ

How many builders should I get tenders from?

Three is a sensible number. It gives you enough comparison without becoming overwhelming. More than five often leads to confusion rather than clarity. Focus on quality of builders rather than quantity of quotes, and ensure each builder is pricing the same information.

How detailed should a renovation tender be?

A good tender should clearly describe the scope of work, materials, labour, timeline, and exclusions. It does not need to run to dozens of pages, but it should leave little room for interpretation. For example, instead of “kitchen install”, it should state supply or install only, number of units, and allowance values.

Is it normal for renovation costs to change after the tender?

Some change is normal, especially where provisional sums are involved or hidden issues are uncovered. However, large increases often point to poor initial scoping. A well prepared tender should keep changes within a controlled range, typically within your contingency allowance of 10 to 15 percent.

Should I always choose a local builder?

Local builders often have better knowledge of local planning authorities, suppliers, and inspectors. They may also have established relationships with Building Control officers, which can help keep projects moving. That said, competence and transparency matter more than postcode.

What certifications should my builder have?

General builders may not hold a single universal certification, but individual trades should be properly accredited. Electricians should comply with recognised schemes such as NICEIC. Gas engineers must be Gas Safe registered. For larger projects, consider whether a structural warranty provider such as NHBC is involved.

Do I need planning permission for my renovation?

Not always. Many home improvements fall under permitted development rights, particularly rear extensions, loft conversions, and internal alterations. However, there are strict limits on size, height, and design.

You will usually need planning permission if:

• Your property is listed
• You live in a conservation area with restrictions
• Your extension exceeds permitted size limits
• You are building to the front of the property

Even where planning permission is not required, Building Regulations approval almost always is. Always confirm with your local authority or through the Planning Portal before starting work.

Final Thoughts

Asking the right renovation tender questions at the start of your project is one of the most effective ways to stay on budget and avoid disputes. The more detail you clarify early, the smoother your build will run.

If you are ready to move forward, the easiest way to start is to post your project on BookaBuilderUK and receive free quotes from vetted local tradespeople.