Rates are developed from surveys and collective bargaining agreements

How are prevailing wages established and what is the process?
Trades are generally surveyed every three years to determine the prevailing wage
rates.
- Contractors and unions are surveyed to determine the wages and benefits
that are being paid for each job classification. This list is established
using industrial insurance, Intent and Affidavit filing, and licensing
data.
- Prevailing wage rates are calculated for each job classification based
on the survey data – such as carpenters, electricians, laborers,
etc. The method for calculating prevailing wage is as follows:
- Largest City in County – Majority Wage:
If more than one-half of all hours reported in the largest city in
a county are worked at one wage rate, then that majority wage rate
becomes the prevailing wage for the whole county.
- Largest City in County – Average Wage: If
there is no majority wage rate, then a weighted average wage is computed
using data from the largest city in a county. The weight attached
to each wage is the total number of hours reported to be worked at
that wage.
- County Average: If no hours are reported in a
county’s largest city, then a weighted average wage is computed
using countywide data.
- Existing Wage Rate – Remains in Place: If
no data is reported for the entire county, then the county’s
old prevailing wage is retained as the new prevailing wage.
How often are prevailing wage rates published?
Prevailing wage rates are published the first business day in August and
in February and take effect 30 days after publication. The publications
are necessary to adjust the rates based on rate surveys, changes to the
minimum wages, and changes to rates that are based on a union majority.
Note: Prevailing Wages established based on a collective
bargaining agreements (CBA) may be adjusted up or down at the semi-annual
wage publication based on changes to the CBA.
Wage and Hour Surveys
Look up when the last wage survey for a trade took place and when the next surveys are scheduled to determine the prevailing wage rates.
For more detailed information on survey methodology, see WAC
296-127-019.