How to Read a Roof Condition Grade: What A–F Really Means for Your Building

How a site inspection becomes your Roof Condition Report, and what each grade really means.

Commercial roof grades offer a fast, clear way to understand the condition of a roof at a glance. But the grade is only the starting point. Behind every letter, A through F, are the details that determine urgency, budget planning, and how much risk a facility is carrying.

At Nations Roof, we use a simplified A–F scale to help building owners, facility teams, and portfolio leaders make sense of inspection findings and plan ahead. This post explains what each grade means, and the real-world factors that can shift a roof from “borderline” to “urgent.”

How a Site Inspection Becomes Your Roof Report

Before a roof is assigned an A–F grade, it begins with a detailed on-site inspection performed by a certified Nations Roof technician. This inspection is the foundation of the entire Roof Condition Report — and ensures the grade reflects not only what the roof looks like today, but how it is likely to perform under future conditions.

During the inspection, our teams walk the entire roof and document:

• Membrane condition, seams, flashings, terminations, and penetrations

• Signs of wear such as alligatoring, scrim exposure, blistering, or failing details

• Drainage performance, ponding areas, and downspout/gutter condition

• UV exposure impacts, storm or wind-related deterioration

• Previous repairs and whether they are holding or beginning to fail

• Access limitations or safety concerns

• Deck condition when visible from below, including rust, softness, or saturation

All findings are logged with photo documentation, mapped locations, and technician notes.
These are then translated into a clear Roof Condition Report that includes:

• The roof’s A–F grade

• Estimated remaining service life

• Recommended repairs

• Priority and urgency levels

• Budget considerations for planning and capital forecasting

This inspection-to-report workflow gives owners and facility teams a full understanding of urgency, risk, and next steps, instead of leaving them to interpret raw technical data alone.

Understanding the A–F Roof Inspection Grading Scale

A – Excellent (8+ Years Remaining)

Roof performing as designed. No active defects; routine maintenance only.

B – Good (5–7 Years Remaining)

Minor wear and isolated repairs recommended; no active leaks.

C – Fair (2–5 Years Remaining)

Aging visible. Recurring minor leaks or early degradation beginning to impact performance.

D – Poor (1–2 Years Remaining)

Active issues, failing previous repairs, and rising risk of system-level deterioration.

F – Failing (<1 Year Remaining)

Frequent leaks and widespread failures. Roof replacement is strongly recommended.

This scale keeps reporting simple, consistent, and easy to understand, especially when managing multiple properties.

When a C Is Really a D

Red flags that typically push a roof down the scale:

• Multiple repeat leaks

• Scrim exposure in multiple locations

• Prior repairs failing within 6–12 months

• Ponding lasting more than 48 hours

• Membrane shrinkage, blistering, or open seams

• Insulation saturation confirmed by cuts or thermal imaging

When a D Becomes an F

A roof becomes truly high-risk when:

1. Leaks occur after every rainfall

2. Failures are widespread, not isolated

3. The deck shows signs of compromise

4. The system has exceeded design life

5. Repairs are no longer holding

6. The building contains sensitive operations or high-value materials

These are the situations where “wait and see” becomes “spend significantly more later.”

Why a Roof Grade Is Never the Whole Story

A grade tells you what is happening. The context explains why, and how urgently you need to respond.

Below are the four major factors that move a borderline roof up or down the scale.

 Environment: Climate and Freeze–Thaw Cycles 

Roofs in colder climates break down faster because water expands inside small openings, seams, and surface cracks.

• • Northern climates often accelerate deterioration, making a C behave like a D.

  • Milder regions may see slower degradation, even with similar wear patterns.

Failure Modes: What’s Actually Breaking Down

The type of failure matters as much as the presence of failure.

Common examples include:

• • Scrim exposure (membrane worn down to reinforcement)

  • Adhered details losing adhesion

  • Alligatoring in asphalt systems

  • Fishmouths or ridges in cap sheets

  • Open seams or failed lap joints

These details help determine how close the system is to structural or moisture intrusion risk.

Building Use: What’s Inside Determines Tolerance for Risk

Some buildings can tolerate occasional leaks. Others absolutely cannot.

Lower sensitivity:

• • Warehouses storing non-sensitive goods

Higher sensitivity:

• • Healthcare

  • Labs

  • Food and beverage

  • Pharmaceutical

  • Data centers

A warehouse with tires may remain operational with a C/D roof while a sterile storage environment cannot.

  Deck Condition: The Hidden Variable

The roof membrane shows the symptoms. The deck reveals the consequences.

High-risk deck conditions include:

• • Metal deck with visible rusting

  • Tectum deck vulnerable to rapid moisture damage

  • Wood decks with soft spots

  • Concrete decks with cracking or spalling

A borderline C can quickly become a D when moisture begins affecting the deck.

How Owners and Facility Teams Should Use Roof Grades

Roof grades help:

• Prioritize capital budgets

• Plan for replacements before failure

• Reduce emergency service calls

• Protect inventory, operations, and compliance

• Extend the useful life of assets

But the grade alone isn’t the full story.
The insight behind the grade is what drives smart decisions.

This is why every Nations Roof report includes documented observations, photos, and recommendations tied to real-world building use and environmental factors.

What to Do Next

Whether your roofs are graded A, F, or anywhere in between, the most important next step is clarity.

• Get an updated inspection if your grade is more than a year old

• Review any C/D/F sites to understand underlying conditions

• Evaluate opportunities for restoration before replacement

• Build a multi-year plan based on risk, usage, and budget tolerance

Our team can walk through your findings building by building or portfolio-wide.