Questions to ask a renovation contractor before you sign: a checklist

The first question isn't how much, it's for what. A one-line quote with a single large number isn't a quote, it's a trap. You can't tell what it includes, and you can't compare it to another quote. Ask for a bill of quantities (a BOQ): a breakdown of every work item and material separately, with the quantity and the unit price.

A detailed BOQ does two things. It shows you what you're buying, tiling by the meter, electrical points by count, waterproofing by area, and it blocks the most common trick in the trade: a low starting price that fills up with add-ons as the job runs. When everything is itemized up front, an addition is a clear overage you have to approve, not a surprise you discover on the invoice.

Ask what's not included too. An honest contractor tells you up front what falls outside the quote, special debris removal, structural reinforcement that only shows up once a wall is opened, material upgrades you asked for. A quote that leaves everything vague is designed to leave room for additions.

Every contractor will promise you verbally that the work will be excellent. The question is what happens when it isn't. A verbal warranty is worth as much as the person who gave it on the day you need it, and often he's no longer answering the phone. Ask for a written warranty, and ask to see what it covers.

The most important emphasis is on the wet work: waterproofing, plumbing, bathrooms. These are the jobs where a failure surfaces months after completion, under the tiles, somewhere you can't fix without tearing out. A written warranty on wet work isn't a legal document on its own, it's a statement from the contractor that he's confident enough in the work to commit to it on paper.

For us, the written warranty on wet work is a standing part of the engagement, and it rests on how we work: double waterproofing and a documented flood test before tiling. It's easy to give a warranty when you know the work was tested before you closed it up.

The person who sells you the work isn't always the one who does it. With many contractors the actual work passes down a chain of subcontractors who rotate between stages, and sometimes between days. The result is that nobody sees the full picture, the plumber doesn't talk to the tiler, and a problem that falls between two trades is left orphaned.

Ask directly: who will be on site most days? Is it a fixed crew that works together, or people who rotate? A fixed crew knows your project from start to finish, carries information between stages without you having to relay it, and owns the work as a single unit. When something goes wrong, there's one address and not mutual blame.

Ask too who your point of contact is throughout the project. There should be one person you go to with any question, who knows the quote and the decisions already made. Without that, every morning starts with explaining it all over again.

This is an excellent test question, because it reveals whether the contractor understands wet work in depth or just performs it. Bathroom damp is the most expensive renovation fault to fix, because it surfaces long after the room is closed and forces you to tear out finished tile. The only way to prevent it is to prove the waterproofing works before you tile over it.

That proof is a flood test: you seal the drain, fill the wet area with water, and confirm there's no drop in the water level and no damp underneath or in the adjoining walls. Tiling starts only after the test passes. A contractor who skips this step saves a few hours now and rolls a year-from-now repeat renovation onto you.

Ask whether the test is documented. For us the flood test is a mandatory stage with documentation, a date and photos of the room flooded before tiling. That's the difference between waterproofing that was done and waterproofing that was also proven to work. For anyone who wants to go deeper, we have a separate guide on bathroom waterproofing failures.

The payment structure tells you a lot about how the contractor works and about the balance of risk between you. The most worrying sign is a demand for a large payment up front, before a single day of work. A contractor who works properly doesn't need your money to start, and your money is your only security that the work gets finished.

Healthy payment is tied to milestones: a small amount at the start, then payments released as defined stages complete, demolition and prep, plumbing and waterproofing, tiling, finish. That way payment always follows work that's already been done and checked, and you're never far ahead of the contractor. Keep a meaningful final payment for the end, after handover and the snag list.

Ask how additions and overages are priced midway through. When everything rests on a detailed BOQ, an addition is a new item priced by the same logic, not an opportunity to set a fresh price once you're already in the middle and dependent on the contractor.

Every contractor will give you a timeline. The more important question is what happens when it breaks, because in a renovation something nearly always surfaces: old pipework found when a wall is opened, unplanned reinforcement, delayed material supply. An experienced contractor won't promise you there'll be no surprises, he'll explain how he handles them when they arrive.

Ask the concrete questions: how many working days realistically, not best case. What happens if something not in the quote surfaces, how it's priced and who approves before work continues. How many hours the crew is actually on site each day. Vague answers here are usually a sign your project will get pushed aside every time another one comes up.

If it's a flat you're living in during the work, or a small-space renovation that needs to function again quickly, define that up front. A small-apartment renovation is run differently from a large project: less open time, more coordination with the life going on around it.

This question sounds small, but it reveals how the contractor sees the end of the job. With some contractors the last day is the day they collect payment and disappear, leaving you with building debris, dust over everything, and a few small defects nobody comes back to deal with.

Ask who is responsible for debris removal and cleanup at the end, and whether it's in the price or an extra. Ask what handover looks like: do you walk the space together, write a snag list, and set when the items get fixed. An orderly handover is what separates work that finished from work that was abandoned.

Finally, ask what happens if a problem surfaces after you've left. The combination of a written warranty, a fixed crew and a point of contact who stays available is what turns 'don't worry' into a promise you can enforce. Without it, the only answer you're left with after handover is hope.