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Understanding Wage Determinations & Heavy Classification for Renewable Energy Projects

How construction type drives wage determinations for renewable energy projects, and why "Heavy" is often the right fit.

What Is a Wage Determination?

A wage determination is a legally-required schedule listing the minimum prevailing wage rates and fringe benefits that must be paid to laborers and mechanics on federal or federally-assisted construction projects. These rates are set based on actual local wage data so that government funds do not distort local labor markets.

There are two main types that may apply:

  • General Wage Determinations – Published for most counties nationwide and valid until revised.

  • Project Wage Determinations – Issued for a specific project when no general determination exists.

Wage determinations include classifications such as laborers, electricians, equipment operators, ironworkers, truck drivers, carpenters, etc. When a needed classification isn’t listed, a conformance request may be required to add it to a determination for that project.

Types of Construction in Wage Determinations

Wage determinations are organized based on the type of construction, which is determined by the nature of the work, not by the project’s title or sector:

  1. Building Construction – Structures with walk-in access like buildings, facilities, and enclosed spaces.

  2. Residential Construction – Single-family homes and apartments up to four stories (plus incidental site work).

  3. Highway Construction – Roads, streets, runways, parking lots, and similar paving work.

  4. Heavy Construction – A catch-all category for projects that don’t fit in the other three.

The Department of Labor’s All Agency Memoranda (AAM) 130 and 131 serve as authoritative guidance for how to classify projects into these categories. Heavy construction is defined as not properly classified as building, residential, or highway and is generally more complex or industrial in nature.

Why Renewable Energy Projects Often Use the Heavy Classification

Renewable energy projects — especially utility-scale solar farms, wind farms, and associated infrastructure — typically involve work that:

✔ Doesn’t resemble standard incoming building construction (like enclosed structures)
✔ Isn’t simply roadway or residential framing
✔ Includes large-scale site prep, grading, foundations, utility trenching, electrical infrastructure, and heavy machinery operations

Because of these characteristics, DOL guidance and practice typically place these projects under heavy construction wage determinations. For example:

  • Utility-scale solar project construction involves earth-moving, grading, panel racking and wiring, and often utility trenching — which are not traditional building or residential tasks.

  • Wind farm work includes turbine foundations, tower erection, heavy equipment operation, and large-scale electrical systems installation.

  • Transmission line and substation infrastructure connected to renewable projects also often fall into heavy construction categories.

This categorization is supported by DOL’s construction definitions and is consistent with the examples used in AAM 130/131 — which describe heavy construction as everything not clearly building, residential, or highway.

Note: Modern guidance (such as DOL’s IRA implementation materials) explicitly points users toward Heavy construction wage determinations for solar and wind energy facilities due to the nature of underlying work and labor classifications involved.

How This Impacts Your Project & Compliance

1. Correct Classification Determines Applicable Wages

The type of construction governs which wage schedule applies. Using the wrong category (e.g., a building WD for a solar site) can lead to underpayment risks and compliance issues.

2. Multiple Wage Determinations May Apply

Some projects include mixed construction types. When one category (e.g., heavy) represents substantial work, separate determinations may be required. AAM 131 clarifies how multiple wage schedules are applied based on project composition and cost thresholds.

3. Conformance May Still Be Needed

Even within a heavy classification, if your project requires labor work not listed in the applicable WD (e.g., a specific trade or classification), you may need to file a conformance request using DOL’s SF-1444 form. This ensures the proper wage rate is applied for work actually performed.

Frequently Asked Questions (Short Answers)

Q: What if the renewable energy project doesn’t involve buildings?
A: Even absent buildings, the project’s heavy construction elements (foundation work, large-scale installations) place it into the heavy category.

Q: Are solar or wind installer wages specifically listed?
A: No — DOL doesn’t list a “solar installer” classification. Instead, relevant standard construction classifications from the heavy determination apply (e.g., laborer, electrician).

Q: When should I check for conformance?
A: After selecting the appropriate WD, compare your project’s labor classifications to those listed. If a needed classification isn’t present, consider a conformance request.

Please see our support article here on how to submit a conformance request:

How to Submit a Custom DOL Wage Determination

Key Takeaways

🔹 Wage determinations are central to prevailing wage compliance and vary by construction type.
🔹 Heavy construction is the most common category for renewable energy projects because of the large-scale and industrial nature of the work involved.
🔹 Understanding and applying the correct wage determination, and pursuing conformance when necessary, protects compliance, bidding accuracy, and worker pay integrity.

References & Guidance

Disclaimer

This article is intended for informational purposes only and reflects current U.S. Department of Labor guidance. Wage determination applicability is based on the nature of the work performed and project-specific facts. Final determinations rest with the U.S. Department of Labor and applicable contracting agencies.