Direct Answer
The most common new-construction roofing defects found at closeout are usually installation and detailing problems that were either missed during construction or were not corrected before the roof was accepted. Common examples include defective membrane seams, incomplete or poorly executed flashing, open or inadequately sealed penetrations, improper edge-metal installation, fastener or attachment deficiencies, damaged membrane or insulation, drainage problems, ponding water, and incomplete correction of punch-list items.
IIBEC has documented examples of new-roof deficiencies including seam wrinkles, poorly sealed pitch pockets, cold or improperly welded thermoplastic seams, inadequate EPDM tape, and dry laps in modified-bitumen systems. IIBEC also emphasizes that roof closeout should include final inspection and correction of deficiencies rather than simply issuing the warranty and moving on. IIBEC — Increased Importance of QA Inspections of Low-Slope Roof Assemblies
Closeout is therefore not just a paperwork exercise. It is the final opportunity to identify conditions that could become leaks, premature failures, warranty problems, or expensive repairs after the building is occupied.
Who This Applies To
- Commercial property owners and developers
- General contractors
- Owners’ representatives
- Architects and engineers
- Commercial roofing contractors
- Roof consultants and RROs
- Facility managers receiving a new building
- Construction managers responsible for project turnover
Not for: A visible roof imperfection is not automatically a functional defect. IIBEC distinguishes between surface imperfections and conditions that actually impair roof performance, so closeout findings should be evaluated against the project specifications, manufacturer’s requirements, applicable standards, and agreed acceptance criteria. IIBEC — Surface Defects vs. Surface Imperfections
1. Defective or incomplete membrane seams
Membrane seams are among the first areas that should receive close attention during a final roof inspection.
Depending on the roofing system, closeout defects can include:
- Open laps
- Incomplete heat-welded seams
- Cold or improperly welded thermoplastic seams
- Wrinkled seams
- Fishmouths
- Inadequate seam treatment
- Insufficient adhesive coverage
- Exposed or damaged reinforcing material
IIBEC has specifically identified seam wrinkles, cold or burnt thermoplastic welds, inadequate EPDM tape, and dry laps in modified-bitumen systems among installation deficiencies encountered during QA inspections. IIBEC QA Inspection Guidance
2. Poorly installed flashings
Roof edges, walls, curbs, penetrations, and transitions require careful inspection because they involve multiple components and changes in plane.
Common closeout findings can include loose or incomplete flashing, improper termination, poorly sealed transitions, inadequate laps, exposed fasteners where they should not be exposed, and flashing that does not conform to the approved detail.
A roof can have an apparently good field membrane and still have a significant water-intrusion risk at a flashing detail.
3. Defective penetration and rooftop-equipment details
New commercial buildings often have numerous roof penetrations for HVAC, electrical, plumbing, communications, exhaust systems, and other equipment.
Closeout inspections should verify that each penetration has been properly integrated with the roofing system.
Typical findings include:
- Incomplete flashing around penetrations
- Improperly sealed pitch pockets
- Gaps around curbs
- Damaged flashing
- Unsealed fasteners or attachment points
- Improper transitions between roofing and equipment supports
- Rooftop equipment installed after the roof without proper restoration of the roofing details
IIBEC has specifically identified poorly sealed pitch pockets as an example of a substandard detail that can remain after a project is otherwise considered complete. IIBEC — QA Inspections of Low-Slope Roof Assemblies
4. Edge-metal and perimeter deficiencies
The roof perimeter deserves particular attention because edge conditions are critical to both weather protection and wind performance.
Inspectors may find loose edge metal, improper fastening, incorrect laps, inadequate sealant, missing components, or installation that does not match the approved edge detail.
These conditions should be evaluated against the project’s specified wind-uplift requirements and the applicable approved assembly rather than simply judged by appearance.
5. Incorrect or deficient fasteners and attachment
Attachment deficiencies can be difficult to identify through a simple walk-through inspection.
Potential problems include:
- Incorrect fastener type
- Improper spacing
- Fasteners installed in the wrong location
- Insufficient penetration into the deck
- Loose or improperly seated fasteners
- Fastener overdriving
- Insufficient attachment of insulation or cover board
- Attachment patterns that do not match the approved assembly
IIBEC notes that attachment deficiencies can compromise wind-uplift resistance and that fastener defects may not always be apparent during a surface-level visual review. This is why closeout QA should compare field conditions with construction documents and attachment requirements. IIBEC — Roof Attachment and Typical Defects
6. Membrane damage caused by other trades
The roof frequently becomes a work platform during new construction. HVAC, electrical, plumbing, glazing, mechanical, solar, and other trades may access or work around the completed roofing system.
IIBEC notes that newly completed roofs can experience water-intrusion problems because low-slope roofs are often used as staging areas, traffic surfaces, and work platforms during construction. IIBEC — Electronic Leak Detection as a Quality Assurance Tool
Closeout inspections should therefore look for:
- Punctures
- Cuts
- Scratches that affect the system
- Membrane tears
- Impact damage
- Damaged flashings
- Displaced protection materials
- Unrepaired penetrations from temporary work
7. Wet insulation or moisture-damaged components
Moisture can enter a roof assembly before the building is complete through weather exposure, leaks, construction moisture, or other pathways.
Moisture-damaged insulation and substrates should not simply be left in place because the membrane looks intact.
IIBEC warns that moisture-damaged roof materials can contribute to corrosion of metal decks and fasteners, decay of wood components, loss of thermal performance, adhesive degradation, membrane deterioration, and other long-term problems. IIBEC Technical Advisory — Moisture-Damaged Roof Substrate Materials
8. Drainage problems and ponding water
Roof drainage should be checked before closeout rather than assuming that the completed roof will drain correctly.
Potential findings include:
- Blocked drains
- Construction debris in drains
- Improperly installed strainers
- Blocked scuppers
- Drainage paths obstructed by equipment or materials
- Unexpected low areas
- Persistent ponding water
IIBEC has documented clogged downspouts and debris-related drainage problems as examples of issues that can remain during roof closeout. IIBEC — Closeout Issues and Roof Drainage
Not every temporary puddle constitutes a roofing defect, but persistent drainage problems should be evaluated against the design, specifications, drainage requirements, and applicable acceptance criteria.
9. Incomplete sealants and termination details
Sealants are frequently used at transitions, penetrations, metal components, termination points, and other roof details.
Closeout findings can include missing sealant, discontinuous beads, poorly tooled sealant, incompatible sealants, gaps, or sealant applied where the approved detail requires a different treatment.
These details should be compared with the manufacturer’s installation requirements and project drawings rather than relying on appearance alone.
10. Improperly installed walk pads and protection
Walkways and protection systems are especially important around frequently accessed rooftop equipment.
Closeout inspection should verify that walk pads or designated walkway systems are installed where required, properly positioned, and not interfering with drainage or other roof components.
Protection is also important because continued construction traffic after the roof is substantially complete can introduce new damage even after the roofing contractor has finished its installation.
11. Roof debris and incomplete cleanup
Construction debris can create both operational and drainage problems.
Closeout should verify that the roof is free of discarded fasteners, packaging, membrane scraps, insulation debris, metal fragments, adhesive containers, and other construction materials.
Drains, scuppers, gutters, and drainage pathways should receive particular attention because debris left behind can interfere with water movement.
12. Unresolved punch-list items
A common closeout problem is not necessarily a single defective roof component—it is an open punch-list item that was identified but never properly closed.
IIBEC has noted that some substandard details are marked for correction but can remain unresolved when there is no effective follow-up inspection. IIBEC — Importance of Follow-Up QA Inspection
A proper closeout process should therefore track each deficiency through:
- Identification
- Documentation
- Assignment of responsibility
- Correction
- Reinspection
- Final acceptance
13. Missing testing and warranty documentation
Even a physically acceptable roof can have an incomplete closeout package.
Depending on the project requirements, the owner may need documentation such as:
- Final roof inspection reports
- Testing records
- Corrective-action documentation
- Manufacturer inspection documentation
- Executed warranty or guarantee
- As-built information
- Product data
- Maintenance information
- Record drawings
IIBEC’s roofing project submittal and protocol guidance includes final punch lists, daily reports, testing certificates, record drawings, and executed warranties among project documentation and closeout items. CRCA/IIBEC/NRCA Roofing Project Submittal and Protocol Guidelines
14. Defects hidden by later construction work
Another closeout risk occurs when another trade installs equipment or finishes work that conceals important roofing details.
IIBEC notes that manufacturer warranty inspections may need to be coordinated before equipment covers or hides pertinent roofing details. IIBEC — Roof Project Commissioning and Closeout
For this reason, final roofing inspection should be coordinated with rooftop equipment installation and other trades rather than scheduled only after everything has been placed on the roof.
15. How a strong closeout inspection should work
A practical closeout process should include:
| Step | What to Verify |
|---|---|
| Document review | Approved drawings, specifications, submittals, and manufacturer requirements. |
| Field inspection | Membrane, seams, flashings, penetrations, edges, drains, and rooftop equipment interfaces. |
| Testing review | Required testing and manufacturer inspection records. |
| Punch list | Every identified deficiency is documented and assigned. |
| Correction | Deficiencies are repaired in accordance with approved requirements. |
| Reinspection | Corrected items are verified rather than simply marked complete. |
| Closeout | Warranty, testing, record drawings, maintenance information, and other required documents are delivered. |
Bottom Line
The most common new-construction roofing defects at closeout are typically defective seams, incomplete flashing, poorly sealed penetrations, edge and termination problems, attachment deficiencies, construction damage, moisture-damaged materials, drainage problems, incomplete cleanup, and unresolved punch-list items.
The key is to identify these conditions before the building is turned over. A properly managed closeout process compares the installed roof against the approved documents, documents every deficiency, verifies corrections, and confirms that the final warranty and project records are complete.
Related Questions
- What quality assurance steps happen during new commercial roof installation?
- What does an RRO look for during commercial roof installation?
- What should a commercial roof observation report include?
- How can a GC reduce roofing quality-control risk on a commercial project?
- What roofing closeout documents should a GC collect before turnover?
- What does a GC need to know about manufacturer warranty inspections on a new commercial roof?
Sources
- IIBEC — Increased Importance of QA Inspections of Low-Slope Roof Assemblies
- IIBEC — Electronic Leak Detection: A Quality Assurance Tool
- IIBEC — Moisture-Damaged Roof Substrate Materials
- IIBEC — Roof Project Commissioning and Closeout
Last reviewed: October 2026
Related Resources
- What Should a Commercial Roof Observation Report Include?
- What Roofing Closeout Documents Should a GC Collect Before Turnover?
- How Can a GC Reduce Roofing Quality-Control Risk on a Commercial Project?
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Disclaimer: This information is provided for general educational purposes and should not be considered legal, engineering, code-compliance, warranty, or other professional advice. Project-specific acceptance criteria should be determined from the construction documents, applicable standards, manufacturer requirements, and requirements of the authority having jurisdiction.
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