The advice is universal and genuinely good. Set aside a contingency, ten or fifteen or twenty percent depending on who you ask and how old the house is, and do not count it as part of your budget.
People follow it. They set the money aside. And then the overrun happens anyway, because the contingency was spent long before the thing it existed for ever occurred.
What a Contingency Is Actually For
Worth being precise, because the precision is the whole point.
A contingency covers the unknowable. It is the money you hold against the things that cannot be priced in advance because nobody can see them yet. Knob and tube wiring behind the plaster. A subfloor that has been quietly rotting under the dishwasher for eleven years. A joist somebody notched badly in 1978. Asbestos in a floor tile. A bathroom drain that turns out to run the wrong direction.
These are real, they are common in older houses, and they are genuinely unforeseeable. They are also expensive and non-negotiable, because once a wall is open and the wiring is visible you cannot close it back up and pretend.
That is the job. The contingency sits there, boring and untouched, so that the day somebody calls you from the site with bad news, the answer is “fine, do it” rather than a difficult conversation with a bank.
How It Actually Gets Spent
Here is the pattern, and it is remarkably consistent across projects.
Week one, the cabinet supplier mentions that for a modest amount more you could have soft-close drawers throughout. It is a small number against the size of the project. You say yes, obviously, because you are going to live with these drawers for fifteen years and the increment is trivial next to the total.
Week two, you are standing in the half-demolished bathroom and realise the tile you picked looks wrong against the light in that room, and the one you now want is somewhat more per square foot. Also small. Also obviously worth it.
Week three, while the electrician is already in the wall, it would be silly not to add the two outlets you have always wanted on the island. The marginal cost of doing it now rather than later is genuinely tiny. Everyone agrees.
Not one of those decisions was wrong. Each was individually defensible, each was cheap relative to the whole, and a reasonable person makes every one of them. But none of them was a surprise. They were choices, and they were funded from the money set aside for things that are not choices.
Then in week six the plumber opens the floor.
The Problem Is Visibility, Not Discipline
What makes this so reliable is that nobody is tracking the running total against the reserve while it happens.
Each decision is made in isolation, in a conversation, often standing in a half-finished room with a contractor waiting for an answer. The number being weighed is the increment, and the increment is always small. The thing nobody has in front of them is the cumulative figure: how much of the reserve has already gone, and on what.
Ask most homeowners mid-project how much contingency they have left and you will get a confident guess that is wrong by a wide margin, almost always in the optimistic direction. Not because they are careless, but because the arithmetic has never been done. It lives across a dozen separate conversations, a few emails, some texts and a change order or two that were agreed verbally and written up later.
And the moment you find out is the worst possible moment, because by then the wall is open.
The other thing working against you is that the overruns rarely announce themselves as overruns. A change order for an upgrade and a change order for a genuine structural problem look identical on paper. Both are a description of work and a number. Both get signed in the same hurried way. Unless somebody has decided in advance which pot each one comes out of, they all come out of the same pot, and the pot is the reserve.
Keep the Reserve Visible and Separate
The fix is not more contingency. A bigger cushion spent the same way lasts slightly longer and runs out at the same point in the story.
The fix is structural: hold the reserve as its own number, log every payment and change order against the line it belongs to as it happens, and be able to see at any moment how much of the reserve is left.
That is the shape of Cobblewood. You enter a total budget and a contingency as a separate reserve, split the rest into line items, and log deposits, progress payments, receipts and change orders against their lines as they occur. When a line goes over, it tells you which line, by how much, and what is still left in contingency to cover it. The alert arrives when you log the entry rather than at the end.
No bank connection is involved. You type everything in and the arithmetic is done for you, which sounds unambitious until you consider that the arithmetic is precisely what nobody does.
There is a second benefit that shows up later. Because upgrades and genuine surprises are logged distinctly, you can see at the end which was which. That is useful information about how you make decisions under pressure, and it is unavailable to anyone whose record is a shoebox of receipts.
Spend It Deliberately If You Spend It
None of this means the soft-close drawers were a mistake. You will like them.
It means the decision should have been made with the real number visible: not “this upgrade costs a bit extra,” but “this upgrade costs a bit extra and takes the reserve from eighty percent to seventy, in week one, before anybody has opened a wall.” Plenty of people would still say yes. They would be saying yes to something they could see.
A contingency you have spent on choices is not a contingency. It is just the rest of the budget, arriving in a different envelope.
