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.”
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.
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.
Roof performing as designed. No active defects; routine maintenance only.
Minor wear and isolated repairs recommended; no active leaks.
Aging visible. Recurring minor leaks or early degradation beginning to impact performance.
Active issues, failing previous repairs, and rising risk of system-level deterioration.
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.
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
A roof becomes truly high-risk when:
Leaks occur after every rainfall
Failures are widespread, not isolated
The deck shows signs of compromise
The system has exceeded design life
Repairs are no longer holding
The building contains sensitive operations or high-value materials
These are the situations where “wait and see” becomes “spend significantly more later.”
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.
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.
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.
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.
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.
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.
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.