Unknowns and contingency
What is still unknown about your building, and what that reserve is worth
A flat percentage contingency treats all houses alike. Two kitchens with identical budgets can carry completely different risk, and the difference is not luck — it is a list of specific, nameable things that are currently unknown about the building. This page enumerates yours and derives the reserve from them.
What your building has not told you yet
Derived contingency
$15,428
6 unresolved unknowns, 2 of them capable of changing the size of the job rather than its price. Weighted by severity, that derives a reserve of 26.6 percent, or $15,428 on a $58,000 subtotal.
Each unknown carries your weight per unknown multiplied by a severity factor of ours — 0.5 for watch, 1 for material, 1.8 for severe. On these answers: (4 × 1 + 2 × 1.8) × 3.5% = 26.6%. The severity factors are our own assumption, not a published standard.
The $58,000 project subtotal pre-filled above is an example — Illustrative assumption — not a market quote. Enter your own subtotal.
6 of these can be closed before a contractor writes a number, and each one you close takes its own weight out of the reserve above. That is how this tool’s reserve gets smaller: by turning unknowns into knowns.
Your unknowns, one at a time
Ungrounded circuits feeding the kitchen — material
Why it is on your list. You identified ungrounded two-wire circuits.
What goes wrong. New kitchen receptacles need a ground path. Without one, the electrician is running new home runs rather than extending what is there, and the panel needs the spaces for them.
How to close it before anyone bids. An inexpensive plug-in receptacle tester from a hardware store will show whether a receptacle has a ground connection.
Galvanised supply piping — severe
Why it is on your list. You identified galvanised or mixed supply piping.
What goes wrong. Older galvanised pipe can be corroded inside, and cutting into it can expose more pipe that needs replacing. A sink move can become a supply replacement back to a sound connection point, and where that point is cannot be known until it is cut.
How to close it before anyone bids. Ask the plumber to cut one accessible section and look at the bore. The inside diameter tells you more than the outside ever will.
Plaster over wood lath rather than drywall — material
Why it is on your list. You identified plaster on lath.
What goes wrong. Plaster demolition takes more labour than drywall and produces more debris. Patching plaster to a flat, paint-ready plane next to a new drywall section is a skill to ask each crew about.
How to close it before anyone bids. Remove one receptacle cover plate and look at the cut edge.
Pre-1980 materials disturbed by demolition — severe
Why it is on your list. The house dates from 1948 and walls are being opened to the studs.
What goes wrong. Sheet flooring, mastic, joint compound and pipe insulation from this era can require testing before demolition and licensed handling afterwards. Discovering it mid-demolition stops the job while a lab result comes back.
How to close it before anyone bids. Have samples taken and tested before the crew mobilises, so the result is known for the whole project. (The 1980 cut-off that puts this card on the list is ours, not a regulatory date.)
Out-of-level floor under new cabinets — material
Why it is on your list. You reported the floor feels uneven.
What goes wrong. Cabinets are shimmed to level, not to the floor. A significant slope means tall shims, a visible gap at the toe kick, and a countertop that reads crooked against a level wall line. Correcting the floor is a separate scope from the kitchen.
How to close it before anyone bids. Put a long level or a laser across the room in both directions and write the worst deviation down. That single measurement is useful to each bidder.
Earlier work with no permit record — material
Why it is on your list. The permit history has not been checked.
What goes wrong. An inspector who finds unpermitted work adjacent to your scope can require it to be brought into compliance before signing off the work you actually wanted.
How to close it before anyone bids. Ask your building department how to look up the permit history for your address. Look before you file, not after.
How a contingency is supposed to shrink
A contingency is not negotiated down. It shrinks when unknowns become knowns, and an item above with a closing action attached is an unknown you may be able to convert in an afternoon. That is the mechanism, and much of it needs no trade skill.
- Look at what you can see. A receptacle cover plate, the cut edge of a wall, the pipe under the sink, the label on a joist. Four observations can settle four items.
- Pull the permit history; ask your building department how to look it up for your address.
- Put a level across the floor in both directions and write down the worst deviation. One measurement, useful to each bidder.
- If the house is older and walls are opening, have materials tested before mobilisation rather than during demolition (this tool flags houses built before 1980, a cut-off of ours). The result is good for the whole job and a stopped job is not.
- Then re-run this page. Watch the reserve fall as each unknown turns into a known, and take the difference back into the budget deliberately.
What to put in the contract about all this
- A written allowance for exploratory opening, so nobody is negotiating in the middle of a demolition day.
- An agreed hourly rate and markup for genuinely unforeseen work, set before it is needed rather than after.
- A requirement that any change over an agreed threshold is documented and signed before the work happens, not billed after it.
- A clear statement of who pays for delay caused by an inspection failure, and who pays for delay caused by a late material order.
- Photographs of each wall and floor cavity before it is closed up, which cost little and help settle later arguments about what is behind the finish.