Contingency in a Renovation Budget: Why You Need One

Even the most accurate estimate cannot foresee hidden problems and later decisions. We explain what a contingency is for, what determines its size and how to manage it.

Setting the renovation budget equal to the bottom line of the estimate seems natural: the work is priced, the materials are counted, so the cost is known. Experience shows, however, that an estimate prices what is known, while a renovation always contains some unknowns. A contingency is not mistrust of the contractor or pessimism; it is a normal tool for managing that uncertainty.

What a contingency is for

Extra costs usually come from three groups. First, conditions that stay hidden until a wall is opened: worn pipes, a weak ceiling slab, rotten timber flooring, an old plaster layer far thicker than expected. Second, quantity refinements: more material than planned to straighten crooked walls, unexpected preparation work. Third, the client’s own decisions: choosing a better material mid-project, asking for an extra lighting point, changing the purpose of a room.

The first two groups are not necessarily the contractor’s fault, because no inspection can reveal them fully. The third is entirely natural: people refine their ideas once they see the space taking shape. Without a contingency, each of these situations leads either to work stopping or to compromises on quality.

What determines its size

There is no single percentage that suits every renovation, and quoting a universal figure would be misleading. Risk factors set the size of the reserve. A larger contingency makes sense when:

• the building is old and the condition of its services is unknown;
• no detailed technical inspection or opening-up was carried out beforehand;
• the layout changes or work is close to load-bearing structures;
• there is no design project, or it is incomplete;
• there are many imported materials and made-to-order items;
• the client is still undecided on some choices.

Conversely, in a new building with a complete design, a detailed estimate and approved materials, the risk is much lower and the reserve can be smaller. In other words, the best way to reduce the contingency is not to cut it, but to reduce uncertainty before work begins.

One way to do this is to make a few small openings before the renovation: lifting part of the bathroom floor, opening a wall where old pipes run, or checking a weak-looking spot in the ceiling. These checks cost little compared with the whole job, but they bring the biggest surprises to light early.

How to hold the reserve

The main rule is to keep the contingency separate. If it is mixed into the general budget, it gets spent in the first weeks on pricier tiles or a decorative light, and when a real surprise appears there is nothing left.

A practical approach is to write the estimate total and the contingency as two separate lines. The reserve is drawn on only for a specific reason, with a short note: “replacing the old drain pipe in the bathroom”, “extra levelling of the hallway wall”. By the end of the renovation it is clear where the money went.

Spending the reserve on aesthetic wishes is not forbidden, but it should be a conscious decision. Ideally, keep a good share of such wishes for the end of the project: if no unexpected technical problem has appeared, the remaining reserve can comfortably go towards décor or extra features.

Agreeing changes with the contractor

How extra work is approved also determines how quickly the reserve runs out. A useful contract rule is this: when the contractor finds work outside the estimate, they first notify the client, show the reason with photos, submit the scope and cost in writing and proceed only after approval.

Emergencies are the exception – if a leak is found, the water must be shut off immediately. Even then, the follow-up repairs go through the agreed procedure.

A time contingency too

Alongside the financial reserve, think about a time reserve. Extra work means not only cost but also days. For a family renting elsewhere or with a fixed moving date, leaving no slack in the schedule is especially risky. Rather than planning completion right up against moving day, leaving a gap between the two reduces stress.

Quick checklist

• Size the contingency according to the property’s risk factors.
• Keep the reserve on a separate line from the estimate.
• Record every use with a short note of reason and scope.
• Include an approval procedure for extra work in the contract.
• Leave decorative wishes for the end of the project where possible.
• Plan a time reserve alongside the financial one.

Zaferoğlu İnşaat's design projects include drawings and computer models, and when decisions are made in advance, budget uncertainty shrinks too. If you already have an estimate, we can look together at where the contingency line belongs and how large it should be.