Questions to Ask a Builder Before You Commit

Questions about the firm

Start with who you would actually be dealing with. Ask who visits the site, who writes the quote and who runs the job day to day. On a small firm these may be the same person; on a larger one, ask to meet the site manager before you sign.

Ask what trades are done in-house and which are subcontracted. Most builders use specialists for electrics, plumbing or structural design, which is normal; what matters is that the main contractor coordinates them and takes responsibility for the result.

• Who will be my single point of contact?
• Which trades are your own team and which are specialists?
• Can I see finished projects similar to mine?
• What insurance do you hold, and can I see the certificate?

Questions about the quote

A useful quote is itemised. It should separate the structure from finishes, list what is excluded and show which figures are provisional sums rather than fixed prices. Provisional sums are common for items that cannot be measured until work starts, such as foundations on uncertain ground, but you should know which they are.

Ask how the quote compares with others line by line rather than at the bottom line. Two quotes that differ widely often include different things: one may include the kitchen, decoration or skip hire and the other not.

• Is the quote itemised, and what does it exclude?
• Which items are provisional sums?
• Is the kitchen fit-out priced separately from the building work?
• How are changes I ask for during the job priced?

Questions about drawings and approvals

For an extension or loft, ask who produces the drawings and who submits the planning application if one is needed. Ask whether the builder works with an architect and structural engineer, and whether building control will be through the council or an approved inspector.

If the house is near a boundary, ask about the Party Wall Act. Work on or near a shared wall often needs notice to the neighbours, and the earlier it starts, the less likely it is to delay the start date.

• Who prepares drawings and structural calculations?
• Does this need planning permission or fall under permitted development?
• Who arranges building control inspections and the completion certificate?
• Will a party wall notice be needed?

Questions about the site and the programme

Ask how the work will run while you live in the house: where materials are stored, how dust is controlled, which rooms will be out of use and when the water or power will be off. A builder who has thought about this before the visit ends is usually one who runs a tidy site.

Ask what the main stages are and what could hold them up. Weather, ground conditions, delivery of steel or windows and building control inspections are the usual causes. A realistic answer is worth more than an optimistic one.

• What are the main stages, in order?
• What is most likely to cause a delay?
• Which parts of the house will be unusable, and for how long?
• How will you protect the rest of the house and garden?

Questions about payments

Ask how payments are staged. Payments tied to completed stages, such as foundations, structure, first fix and completion, keep money and progress aligned. Be wary of a large payment before any work begins, beyond a reasonable amount for materials ordered specifically for your job.

Ask what happens at the end: how snagging is handled, what certificates you will receive, such as electrical certification and the building control completion certificate, and who to call if something needs attention after handover.

• How are payments staged against the work?
• What certificates will I receive at the end?
• How is snagging handled?

Questions about the ground and existing house

On extensions in particular, ask what the builder needs to know before the foundations are designed. Clay soils, nearby trees and existing drains are common in Kent and East Sussex gardens and can change the foundation depth or route of drainage. A builder who asks to see where the drains run and looks at the trees is pricing your site, not an average one.

For older houses, ask how the new work will join the old: matching bricks, dealing with uneven floors and connecting to existing heating. These junctions are where most of the craft on a renovation goes.