Renovation budget for a 225 m² detached home in Utrecht — how much contingency?

Y

yard.steady

Homeowner
Established
The difficult part is comparing quotes when each contractor leaves out something different. I am working with a preliminary budget of €194,400 for a 225 m² detached home in Utrecht, covering new kitchen and bathroom work, floors, decorating, electrical inspection and some energy improvements. I am not proposing an extension.

The finish level is fairly moderate; uncertainty around existing services and the order of work worries me more. Moisture behind finishes, inaccessible pipework or electrical remedial work could affect several later trades. Permit timing could also disrupt the programme if any part of the scope requires approval.

Would you set the reserve only after putting every quote into a common scope, or carry a provisional allowance now? I would also welcome specific questions for the surveyor and bidders that would expose the largest exclusions before contracts are agreed.
 
I’d think in terms of roughly 15% if the surveys are thorough and the scope is tightly defined, nearer 20% while access and existing services remain uncertain. More important, rewrite every quote into the same schedule: demolition, disposal, preparation, labour, materials, access, testing and making good. An attractive total can simply mean more exclusions.
 
How much of the electrical and plumbing scope is actually visible at this stage? “Electrical checks” could finish with a report, or uncover work that affects freshly painted walls and new flooring. Likewise, bathroom pricing means little until you know whether pipes are accessible.

I would ask the surveyor to identify moisture signs and likely service routes, then ask each contractor what happens if those assumptions prove wrong.
 
The material-ordering dates changed my view. The reserve matters, but it cannot correct a job carried out in the wrong order.

I would investigate questionable areas before finalising kitchen dimensions or committing to flooring and decoration. Decisions on damp, wiring and pipe routes should be made while access is still available, with the cost and authority for opening up clearly defined. Otherwise a modest investigation can turn into uncontrolled remedial work.

I would also ask each contractor for the last safe date for ordering long-lead items. Buying too soon fixes dimensions based on assumptions; buying too late can hold up every trade that follows.
 
Agreed on sequencing, although investigation itself needs a defined limit. Otherwise “we had to open more” becomes an uncontrolled instruction. For each uncertain area, ask for a price to investigate, a written finding, and approval before remedial work proceeds.

Does “no extension” also mean no walls, openings or heavy fixtures are changing? If not, structural work could still enter the scope even without adding floor area.
 
Give bidders a one-page exclusions table and require them to complete it. Include structural alterations, electrical remedial work, plumbing diversions, moisture treatment, drying time, protection of retained areas, waste removal, scaffolding or other access, final cleaning and repair after trades.

I’d also ask who determines whether any part needs permission, who submits it, and how that timing affects the programme. Don’t let permit assumptions sit silently inside the proposed start date.
 
One caveat: the lowest-risk sequence may not be the fastest. Waiting for opening-up results before confirming materials can extend the programme, while ordering first transfers the risk to fit and storage. Decide which items genuinely need early commitment and which can wait.

For energy upgrades, ask how each measure interacts with moisture and ventilation rather than treating them as isolated line items.
 
This has helped me spot the main weakness: I had treated “electrical checks” and the energy items almost as completed packages, when they are partly investigations that may create follow-on work. I’m going to separate investigation costs from remedial allowances and have all quotes returned against one exclusions table.

I’ll also avoid assuming that no extension means no possible structural input. The next step is to clarify every proposed opening or alteration before fixing the contingency.
 
That should make the reserve more meaningful. I’d divide it into two pots: allowances tied to named uncertainties, and a smaller general contingency controlled by you rather than absorbed into the contract price. Record each release with its cost and programme effect.

Before signing, ask for a simple sequence showing surveys, opening-up, decisions, orders, service work, drying, finishes and handover. Conflicts will be easier to see there than in a total-price quote.
 
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