Most change orders are symptoms of unclear scope boundaries. Strong specifications define conditions of acceptance, measurement standards, and responsibility lines up front. Every ambiguity in a coating scope is a potential change order. Every undefined expectation is a future dispute.

This guide covers the practical elements of coating scope writing that, when addressed clearly before work begins, dramatically reduce the surprises that generate change orders during execution.

Defining Surface Preparation Standards

Surface preparation is the most common source of change orders in coating projects. The work required to achieve a specified prep standard can vary enormously depending on the existing condition of the substrate, and vague prep language leaves that cost exposure undefined.

Specifying by Objective Standard

Always reference recognized industry standards rather than subjective descriptions:

  • For steel: Specify SSPC/NACE joint standards (e.g., SSPC-SP 5 / NACE No. 1 White Metal Blast Cleaning, SSPC-SP 10 / NACE No. 2 Near-White Blast Cleaning, or SSPC-SP 6 / NACE No. 3 Commercial Blast Cleaning). These standards define cleanliness in objective, verifiable terms with visual reference comparators.
  • For concrete: Reference ICRI Concrete Surface Profile (CSP) guidelines, specifying the target CSP number (e.g., CSP 3 to CSP 5 for typical resinous coatings). Also specify the method for achieving the profile (diamond grinding, shot blasting, or scarification) if the method matters for the project.
  • For previously coated surfaces: Define the required condition of the existing coating after preparation. Is the specification calling for full removal to bare substrate, or is feathering and spot repair of sound existing coating acceptable? This distinction can represent a 3x to 5x difference in preparation cost.

Addressing Existing Conditions

The scope should describe the known existing conditions and clearly state the contractor’s responsibility for conditions that differ from what is described:

  • Document the current coating system (type, approximate thickness, adhesion condition) based on a pre-bid survey.
  • State whether lead paint, asbestos-containing materials, or other hazardous coatings are present or suspected.
  • Define who bears the cost risk if existing conditions differ from what was described at bid time. This is where most preparation-related change orders originate.

Verification Methods

Specify how preparation quality will be verified:

  • Visual comparators (SSPC-VIS standards) for cleanliness
  • Replica tape or digital profile gauge (per ASTM D4417) for surface profile
  • Soluble salt testing (per SSPC Guide 15) where required
  • Moisture testing method and acceptable thresholds for concrete substrates

When the contractor knows exactly what will be measured and what will pass inspection, they can price accordingly and execute with confidence.

Defining Environmental Limits

Environmental conditions during coating application directly affect performance. A scope that does not define environmental limits invites either quality problems or work stoppages that generate delay claims.

Temperature Boundaries

Specify:

  • Minimum and maximum ambient air temperature for application of each coating product
  • Minimum and maximum substrate surface temperature for application
  • Minimum surface temperature above dew point (typically 5 degrees Fahrenheit, but confirm against the coating manufacturer’s requirements)
  • Minimum and maximum temperature during cure for each coat

Humidity Limits

Specify the maximum relative humidity permitted during application. Most coating manufacturers set limits between 80 and 85 percent relative humidity, but some products are more restrictive. For moisture-sensitive systems (polyaspartics, some urethanes), humidity control during cure may be as important as during application.

Response Actions When Conditions Drift

Define what happens when environmental conditions move outside the specified limits:

  • Stop-work protocol: At what point must the contractor stop application? Who has authority to call a stop?
  • Resumption criteria: What conditions must be met and for how long before work can resume?
  • Cost responsibility for weather delays: Is weather delay time compensable, or is it included in the contractor’s bid? This is one of the most frequent sources of change orders on exterior projects.

Explicitly addressing these scenarios in the scope eliminates the ambiguity that fuels disputes when conditions deteriorate mid-project.

Inspection Methodology and Measurement Standards

A scope that specifies what will be inspected and how prevents disagreements about acceptance after the work is done.

Film Thickness Measurement

Define:

  • Measurement method: Magnetic gauge (Type 1 or Type 2 per SSPC-PA 2), eddy current gauge, or destructive method for concrete substrates.
  • Measurement frequency: Number of spot measurements per defined area (e.g., five spots per 100 square feet, three readings per spot).
  • Acceptance criteria: Minimum DFT, maximum DFT, and how averages are calculated. SSPC-PA 2 provides a structured methodology for evaluating DFT measurements against a specification. Reference it directly and specify which level (Level 1 through Level 5) applies.
  • Remediation for non-conforming areas: What happens when readings fall below the minimum? Define the corrective action (additional coat, spot application) and who bears the cost.

Adhesion Testing

If adhesion testing is required:

  • Specify the method (ASTM D3359 cross-hatch or ASTM D4541 pull-off).
  • Define the minimum acceptable adhesion value in psi for pull-off tests.
  • State the number of tests per area and the location selection criteria.
  • Clarify whether test locations must be repaired and re-tested after testing.

Holiday Testing

For immersion or containment applications:

  • Specify the method (low-voltage wet sponge per NACE SP0188, or high-voltage spark test).
  • Define the voltage setting methodology (typically a formula based on coating thickness).
  • State the acceptance criteria (zero holidays, or a defined maximum per area).
  • Define the repair and re-test protocol for detected holidays.

Allowances and Exclusions

Allowances and exclusions define the boundaries of the contractor’s responsibility and are among the most effective tools for reducing change orders.

Unit-Price Allowances

For work elements where the quantity is uncertain at bid time, include unit-price allowances:

  • Surface repair allowance: A defined number of square feet of concrete repair (patching, crack filling, spall repair) included in the base price, with a unit price for additional work. This prevents the contractor from either over-pricing for unknown repairs or submitting change orders for every defect discovered during preparation.
  • Additional coat allowance: For areas that may require an extra coat to achieve minimum DFT, include an allowance with a defined unit price per square foot.
  • Hazardous material allowance: If there is a possibility of encountering lead paint or other hazardous materials, include a defined scope for testing and abatement with a unit price for additional quantities.

Clear Exclusions

State what is not included in the scope:

  • Scaffolding or access equipment (or confirm it is included and specify the type)
  • Containment and environmental controls for abrasive blasting
  • Disposal of hazardous waste
  • Protection of adjacent surfaces, equipment, or inventory
  • After-hours or weekend work premiums
  • Mobilization and demobilization for schedule interruptions beyond the contractor’s control

When exclusions are explicit, contractors price what is included with confidence, and owners are not surprised by costs they assumed were covered.

Responsibility Matrix

A responsibility matrix assigns every significant project task to a specific party. This eliminates the gray areas where change orders breed.

Key Responsibilities to Assign

TaskOwnerContractorThird Party
Access and scaffolding
Surface preparation
Substrate repairs
Environmental monitoring
Material procurement
Quality inspection
Daily documentation
Final inspection and acceptance
Punch list completion
Waste disposal
Protection of adjacent areas

Fill in each cell with the responsible party. Where responsibility is shared (e.g., the owner provides access and the contractor provides scaffolding), define the division explicitly.

Third-Party Inspection

If a third-party coating inspector is involved, define:

  • Who retains and pays for the inspector
  • The inspector’s authority (advisory vs. stop-work authority)
  • The inspector’s schedule and response time expectations
  • How disputes between the inspector and the contractor are resolved

Undefined inspection authority is a frequent source of project friction. Clarify it in the scope.

Acceptance Criteria

The scope should define exactly what “complete” and “acceptable” mean.

Quantitative Acceptance

  • DFT within specified range per SSPC-PA 2
  • Adhesion at or above the specified minimum
  • Holiday testing with zero detected holidays (or per the defined threshold)
  • Surface profile within the specified range

Visual Acceptance

  • Define what visual defects are unacceptable: runs, sags, drips, dry spray, overspray, color variation, foreign inclusions
  • Reference SSPC visual standards where applicable
  • Specify whether the final visual inspection is conducted under normal facility lighting or under supplemental lighting conditions

Warranty Terms

Define the warranty period, what it covers (materials, labor, or both), and the conditions under which the warranty applies. A warranty that excludes normal wear, chemical exposure, or mechanical damage may have limited practical value. Align warranty terms with the actual service conditions the coating will face.

Writing Scopes That Work

A well-written coating scope does not need to be long. It needs to be specific about the things that generate disputes: preparation expectations, environmental limits, measurement standards, cost boundaries, and responsibility assignments. Every hour invested in scope clarity before bid day saves multiples in avoided change orders, avoided disputes, and avoided rework during execution. The best scopes are written by people who have lived through the problems that vague language creates.