Construction change orders explained: how Hamilton builders handle surprises

Here is the cold truth of renovating: nobody can see through drywall. A Hamilton century home or a 1960s bungalow can hide old wiring, notched joists, past DIY plumbing or work that was never permitted. Until the wall is open, any quote is a good estimate of the visible part.

That is not a reason to avoid renovating an older home. It is a reason to agree, before you start, on exactly how surprises will be handled.

What is a change order?

It is a written amendment to the original contract. It describes what is changing (the scope), what it costs (or saves), and how it affects the schedule. It becomes part of the contract once both parties sign. It protects both sides: you know the price before you agree, and the contractor is not working on a handshake.

Changes come from two places. Hidden conditions are things nobody could have known, like rot behind a tub. Owner changes are things you decide, like upgrading the tile or adding pot lights. Both should follow the same process.

What is the difference between an amateur and a professional response?

The amateur approach is to keep working and add the cost to the final invoice, so you learn about it when it is too late to choose. The professional approach looks like this:

1. Stop and protect. Pause work on the affected area and make it safe.
2. Document. Photos, a description and, where needed, input from an engineer or inspector.
3. Present options. Often there is more than one way to fix it, at different costs.
4. Price it in writing. Labour, materials and schedule impact, separately.
5. Get approval. A signed change order, paper or electronic, before the work proceeds.

The aim is that you are never surprised by a number and always have a choice.

How much contingency should you set aside?

A common rule of thumb is to hold back about 10 percent of the renovation budget as contingency, and more for older homes or projects that open up a lot of existing structure. It is your money, not the contractor's, and if you do not use it, you keep it. Treat it as part of the budget, not as a bonus. Our cost guide has planning ranges to start from.

The paper-trail rule

Never agree to a change over a casual text or a hallway conversation. A text that says "sounds good" is not a price. Insist on a short document that states what is changing, what it costs, and the new completion date. If your contractor offers this without being asked, that is a very good sign. If they resist, reconsider.

It also helps to agree up front on how change orders will be priced, for example labour rates and the markup, so there are no negotiations in the middle of a job. This works best inside a fixed-price contract, where the original scope is clear enough that you can tell what is a real change.

Real examples from our jobs

Everything above is easier to see in examples. These are anonymized from our own projects, and each one ended up as a change order.

• "The floors are level." A client told us their floors were level, so the quote did not include levelling. Once the old flooring was out, we needed more than 20 bags of self-levelling compound to get the surface flat enough for tile and new flooring. Laying finished floors over an uneven base fails later, so the work was necessary, but it was extra.
• Old wiring. In an older home, opening the walls can show wiring that cannot safely be kept. Our electrician had to replace it and install new breakers. It can look like waste, but old wiring behind new finishes is a safety risk, and electrical work should be done by an ESA-licensed contractor.
• "It's just painting." A job booked as painting only turned out to have leaking walls. We brought in a plumber to repair the leak, then replaced damaged drywall and redid screws, mudding and sanding. Paint over a wet wall would have failed in months. Read why prep decides how long paint lasts.
• Changing the plan midway. When a client changes a finished or half-finished part of the job, we have to demolish what was already built, rebuild it, and often re-order materials. That is a real cost of labour and materials, and the schedule moves with it.
• Saving the old baseboards. Clients often ask to keep original trim. Removing it intact is rarely possible, and when it can be done, the reused pieces seldom match new work. If you want a particular look, say so at the quote stage so we can price new trim or careful salvage honestly.

The pattern is the same each time: the surprise is not the problem, the conversation about it is. That is why we write it down before the work happens.

How we learn from every job

We keep a lessons-learned register. At the end of each phase and each project we ask what we did well, what we should improve and how we can be more efficient, then apply it on the next job. Many of the clauses in our contracts today exist because of an entry in that register.

Keep reading

• Fixed-price vs cost-plus: which contract protects your renovation budget?
• Protecting your capital: what a fair renovation payment schedule looks like
• Renovation cost guide: Hamilton area

This guide is general information from a contractor, not legal advice. Rules, prices and ranges change, so confirm current details before you sign a contract.