How to Compare ADU Bids Line by Line

Three builders, three numbers, and a spread of a hundred thousand dollars. The instinct is to assume one of them is greedy and one is a bargain. Usually what has actually happened is that the three bids describe three different amounts of work.

Comparing them properly takes about an hour and is the highest-value hour in the whole project. Here is what to line up.

Put them in one column each

Literally — a spreadsheet with one row per item and one column per builder. The point is not the totals. The point is the rows where one column is empty. That is where the difference lives.

The five things most often missing

• Site work. Excavation, grading, drainage, retaining, haul-off, access protection. The largest source of variance between bids on an ADU, and the easiest to leave out. If a bid does not price your actual ground, it is not pricing your project.
• Utility connections. The side sewer, the water line, the electrical service and the trench between them. Long runs cost real money — see how utility connections work.
• Permit and impact fees. Sometimes included, sometimes listed as “by owner.” Those two words can be five figures.
• Design and engineering. Is the permit set in the number, or does the bid assume you arrive with drawings already done?
• A contingency. A bid with no contingency is not cheaper. It has simply moved the unknowns into your future change orders.

Allowances: where a low bid is manufactured

An allowance is a placeholder for something not yet chosen — flooring, cabinets, fixtures, appliances. Perfectly normal. But allowances are also the easiest lever for making a bid look competitive, because you will not feel them until selection time, long after you have signed.

So for every allowance, ask what it buys. An allowance set at builder-grade when you are picturing something better is not a saving — it is a bill you have not received yet. Two bids with identical totals and different allowance levels are not the same bid.

Read the exclusions page first

Most of the honest information in a construction bid is on the exclusions list, and most people never reach it. Read it before the price. A long, specific exclusions list is usually a sign of a careful builder; a bid with no exclusions at all is a bid that has not been thought through.

Terms that matter as much as the number

• The payment schedule, and whether it tracks completed work rather than the calendar.
• How change orders are priced and approved — in writing, before the work, or after?
• Who carries builder’s risk insurance, and what the contractor’s liability limits are.
• The schedule, and what happens if it slips.
• What the warranty covers and for how long.

Insurance and registration are checkable in about ten minutes and worth doing for every bidder — Washington contractors must be registered with Labor & Industries and carry a bond. Details in what insurance an ADU needs.

When one bid is far below the others

Treat it as a question, not a win. In our experience it is almost always one of three things: scope left out, allowances set low, or a builder who has underestimated the site and will discover that halfway through — which is the worst outcome of the three, because a contractor losing money on your job is a problem you now share.

The useful move is not to reject it. It is to take the lowest bid back to the builder with the fullest one and ask them to price the missing rows. Sometimes the gap closes honestly. Often it disappears.

What an all-in number looks like

We quote with the site work visible rather than buried, because the site is where ADU budgets actually move. The ranges we work from are published on realistic costs rather than held back until you ask, and you can bracket your own project with the cost calculator before you talk to anyone.

More on vetting the firm behind the number in how to choose an ADU contractor, and on the two delivery models in design-build vs. architect plus contractor.

Bring us a bid to read

If you have quotes in hand and cannot tell why they differ, send them over — get in touch and we will tell you what each one is and is not covering, including when somebody else's number is the better deal.