Methodology
How we price a job.
You are entitled to know exactly how we get to the number — including the parts we are least sure about.
Two questions, not one.
Photos and a sentence settle what the work is. A separate step settles the cost.
Measured, not guessed.
Hourly wages come from the Bureau of Labor Statistics, by trade and by metro area.
Where BLS withholds a local figure we use the state or national rate, and label the line. The wage is measured; the multiplier on top is our assumption.
Local hourly wage vs. the national average, by trade and metro
0.78×1.45×
Materials
There is no honest price feed for what this building sells.
Andrew Barlow / Unsplash
Materials are modeled, and we say so.
The construction cost databases are enterprise-only, unlicensable, or forbid this use.
Prices come from our models, then move with the BLS Producer Price Index for that commodity.
Producer price index, Jan 2024 = 100
- Lumber+21%
- Gypsum+2%
One number would be more satisfying, and less honest.
Cost engineers bracket an estimate at this stage and tighten it as the job is understood.
best conveyed through numerical ranges with a point estimate
Fernandes et al. (CHI 2018, n=408) ranked ten ways of showing uncertainty and placed a bare interval eighth of ten.
Expected accuracy of an early-stage estimate
No model ever does the math.
Models produce quantities, hours and unit prices. Code multiplies, sums, and applies waste, tax, permits and markup.
Money is whole cents, so the line items always sum exactly to the total.
Markup is a divisor.
8.3%
What “10 and 10” yields when it is treated as×1.20, not 10%. The error makes every estimate systematically low.
Permits
The rule that applies to your job was written in a building like this one.
Fujiphilm / Unsplash
Likely, never certain.
Thousands of local authorities write their own amendments, so we name who to ask rather than invent a fee.
Seattle, WA
Single-family re-roofing
No permit
Drywall, U.S.
Exemption threshold
16 sq ft — none
Four things we cannot see.
Behind the wall
Rot, mold, failed waterproofing, bad wiring. Listed as unknowns, with a likely cost.
Supplier prices
Adjusted to your market beats a national average. Still not a quote.
Unusual work
Standard jobs are our strength. Bespoke or structural work widens the range.
Your actual room
A contractor standing in it knows things we cannot. A reference point, not a replacement.
If our checks reject a figure, or confidence falls below the floor: no estimate, no charge.A confidently wrong number is worse than none.
We take no money from contractors. In any form.
No lead generation, no referral fees, no sponsored placement. A price authority paid by the people whose prices it describes is not an authority.
Every figure above, and where it came from.
A number about your money with no source attached is a number you have no way to check. These all open.
0.78× – 1.45×, and the D.C. rows (electricians 1.11×, general laborers 0.95×)
§02 Labor
U.S. Bureau of Labor Statistics — Occupational Employment and Wage Statistics (OEWS)
The wages are measured and published by metro area and occupation. The multipliers are ours: each metro’s mean hourly wage for that occupation, divided by the national mean for the same occupation.
Gypsum +2%, Lumber +21%, Jan 2024 → Aug 2026
§03 Materials
U.S. Bureau of Labor Statistics — Producer Price Index (PPI)
Two measured endpoints per commodity, indexed to Jan 2024 = 100. We do not draw the months in between.
−30% / +50% at its broadest, −20% / +30% where the job is well understood
§04 Why a range
AACE International — Recommended Practice 18R-97, Cost Estimate Classification System
The class table is the cost-engineering standard for expected accuracy by estimate maturity. RPs are free to AACE members; the index page lists 18R-97.
“best conveyed through numerical ranges with a point estimate”
§04 Why a range
van der Bles, van der Linden, Freeman & Spiegelhalter, PNAS, 2020
The finding our central rule is built on: a range with a marked likely value costs almost nothing in trust, while a bare point estimate that turns out wrong costs a great deal.
Ten ways of showing uncertainty ranked, n = 408; a bare interval placed eighth
§04 Why a range
Fernandes, Walls, Munson, Hullman & Kay, CHI 2018
Why the range is drawn as a dimension line with the likely value marked on it, rather than printed as two numbers with a dash between them.
Seattle exempts single-family re-roofing
§06 Permits
Seattle Department of Construction and Inspections — Re-Roof Permit
“A permit is not required for re-roof work at one- and two-family homes and townhouses if no changes are made to the building envelope other than adding or replacing insulation.”
Drywall exemption thresholds, “16 sq ft — none”
§06 Permits
No published source
This is a comparison we compiled across local amendments to the model residential code, not a figure any one authority publishes. Until we publish the jurisdictions it was drawn from, it is the only number on this page without a link, and you should treat it as ours rather than theirs.
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In development for iPhone. One email, when it opens.