What should I do if I find evidence of a bad TPO installation?

Direct Answer

If you find evidence of a bad TPO roof installation on a commercial building, document the defects, protect the building against active water intrusion, and arrange an independent evaluation by a qualified commercial roofing professional. Do not immediately cover the suspected defects or allow the original contractor to make undocumented repairs before the condition has been recorded.

TPO (thermoplastic polyolefin) roofing is a single-ply membrane system that relies on properly welded seams, secure attachment, compatible flashing details, and correctly installed drainage and penetration components. Poor workmanship in any of these areas can compromise watertightness, wind-uplift resistance, durability, or warranty compliance.

Start by photographing the suspected defects, collecting the installation specifications and warranty documents, and identifying whether the problems are isolated or widespread. Then obtain a written assessment, notify the responsible contractor and manufacturer when appropriate, and agree on a documented corrective-action plan.

Manufacturer guidance supports inspecting completed roof sections, probing heat-welded seams, correcting identified deficiencies, and completing repairs using compatible materials and approved procedures. See the GAF TPO/PVC Adhered Roofing Systems Manual and GAF’s TPO installation guide.

Who This Applies To

• Commercial property owners and asset managers
• Property and facility managers
• General contractors and developers
• Condominium and HOA boards overseeing commercial or shared-building roofing work
• Construction managers and owner’s representatives
• Owners investigating leaks after a recent roof installation
• Owners preparing to accept a completed roofing project

Not for: This guide does not replace a professional roof inspection, engineering evaluation, contract review, or manufacturer warranty determination. Suspected installation defects should be assessed against the actual project specifications, applicable code requirements, and the specific manufacturer’s instructions.

1. Document the Suspected Defects Before Repairs

Begin by creating a clear record of what you observed. If the roof is newly installed or still under construction, document the issues before they are concealed by additional work.

Record:

• The location of each suspected defect
• Photographs showing the defect and its surrounding area
• The date the condition was observed
• Whether the area is leaking or has leaked previously
• The installation stage when the issue was identified
• The contractor or crew responsible for the affected work, if known
• Any inspection reports or previous repair records

Use roof plans or a marked-up drawing to identify defect locations. For large roofs, assign each issue a reference number so photographs, reports, and repair records can be matched.

Do not rely solely on general statements such as “poor installation” or “bad seams.” Identify the specific observed condition and have the appropriate professional determine whether it constitutes a technical deficiency.

2. Look for Common Signs of Poor TPO Installation

TPO installation defects can appear in seams, membrane attachment, flashing, penetrations, drainage details, and the overall membrane surface.

Potential Defect	What to Look For	Why It Matters
Open or poorly welded seams	Visible separation, incomplete welds, or areas that fail appropriate seam probing	Can create a pathway for water intrusion
Cold welds or inconsistent welds	Areas where the membrane sheets may not be properly fused	Can compromise seam integrity
Wrinkled or poorly positioned membrane	Excessive wrinkles, bridging, or poorly fitted membrane around details	May indicate installation or detailing problems
Improper flashing	Poorly integrated membrane around walls, curbs, pipes, and equipment	Can allow water to enter at transitions
Exposed or improperly installed fasteners	Attachment details that do not match approved system requirements	May affect attachment performance and watertightness
Poorly detailed T-joints	Missing, incorrect, or improperly installed details where seams intersect	Can create vulnerable points in the membrane system
Inadequate drainage details	Poor membrane integration at drains or other drainage components	Can contribute to leaks or drainage-related deterioration
Membrane cuts or punctures	Unpatched damage or repairs that appear inconsistent with system requirements	Can compromise the waterproofing layer

These observations are warning signs, not automatic proof of defective installation. The assessment should establish whether the work complies with the approved specifications and applicable manufacturer requirements.

3. Pay Particular Attention to Heat-Welded Seams

Seam quality is one of the most important areas to investigate on a TPO roof because adjacent membrane sheets must be properly heat-welded to form a watertight connection.

Potential concerns include:

• Open seam edges
• Incomplete or inconsistent welds
• Contaminated welding surfaces
• Improper welding settings or techniques
• Unrepaired seam voids
• Inadequate detailing at seam intersections

A qualified roofing professional should evaluate suspect seams using the appropriate inspection procedures. Seam probing should be performed carefully and in accordance with the applicable manufacturer’s instructions.

GAF’s installation guidance assigns responsibility for initial weld probing to the contractor and calls for completed roof sections to be inspected, defects to be corrected, and repaired seams to be checked after cooling. Review the GAF adhered roofing systems manual for the relevant technical requirements.

Do not assume that a seam is sound simply because it looks acceptable from a distance. Conversely, avoid probing or cutting the membrane yourself if doing so could damage the roof or affect warranty coverage.

4. Check Flashing and Penetration Details

Many commercial roof defects occur where the membrane meets another component rather than in the middle of an uninterrupted roof sheet.

Inspect the installation details around:

• HVAC units and equipment curbs
• Pipes and conduits
• Roof drains and scuppers
• Parapet walls
• Roof edges and terminations
• Skylights
• Expansion joints
• Other roof penetrations

Look for visible gaps, poorly integrated membrane, loose components, damaged flashing, and details that appear inconsistent with the approved system.

Photograph the details and compare them with the approved shop drawings and manufacturer’s installation instructions. A professional should determine whether corrective work is required.

5. Verify the Membrane Attachment and Roof Assembly

A TPO roof is more than the visible membrane. Its performance also depends on the attachment method and the roof assembly beneath it.

Depending on the specified system, review:

• Whether the membrane is adhered or mechanically attached as specified
• Fastener and plate locations where visible or verifiable
• Insulation and coverboard installation records
• Substrate preparation
• Membrane layout and sheet orientation
• Perimeter and corner attachment details
• Compliance with approved wind-uplift design requirements

Some of these conditions cannot be confirmed through a visual inspection alone. The owner may need installation photographs, quality-control records, approved shop drawings, or selective testing performed by a qualified professional.

Do not remove membrane or insulation simply to investigate a suspicion. Any intrusive investigation should have a defined purpose, appropriate authorization, and a repair plan.

6. Determine Whether Water Intrusion Has Occurred

If the suspected installation defect has caused a leak, address the immediate risk to the building while preserving evidence of the condition.

Check for:

• Active leaks during or after rainfall
• Interior water stains
• Wet insulation or ceiling materials
• Moisture around roof penetrations
• Recurring leaks in the same location
• Water accumulation associated with poorly installed details

Protect equipment, inventory, and occupied areas from additional damage. Record the date, weather conditions, affected interior locations, and temporary measures taken.

If the roof is under construction, coordinate temporary weather protection with the responsible contractor. Do not delay necessary emergency protection merely to preserve evidence, but document the original condition as thoroughly as circumstances permit.

7. Compare the Installation With the Contract and Approved Specifications

Before accusing a contractor of defective work, establish what was actually required for the project.

Collect and review:

• The roofing subcontract or installation contract
• Approved roofing specifications
• Manufacturer’s installation instructions applicable to the system
• Approved shop drawings
• Product and assembly approvals where applicable
• Quality-control and observation reports
• Daily installation records
• Change orders and approved substitutions
• Manufacturer inspection or warranty documentation

Compare the observed condition with the relevant requirements. A detail that looks unusual may be permitted by the specific system, while a visually subtle defect may still violate the approved specifications.

For Florida projects, also verify the building-code edition and project-specific approvals applicable to the permit and construction. Do not assume that a generic installation guide alone establishes compliance with every local requirement.

8. Obtain an Independent Professional Assessment When Appropriate

If the suspected defects are widespread, disputed, associated with leaks, or likely to lead to significant repair costs, consider an independent commercial roofing consultant or other appropriately qualified professional.

Ask the professional to:

• Identify and map the observed deficiencies
• Determine whether the findings indicate installation defects
• Compare the installation with the approved documents
• Assess the potential for water intrusion or other performance problems
• Identify whether additional testing is warranted
• Recommend corrective work
• Provide photographs and a written report

For a significant dispute, an independent assessment can help distinguish actual defects from cosmetic concerns and provide a more defensible basis for corrective work.

9. Notify the Roofing Contractor in Writing

Once the issues are documented, send the responsible contractor a written notice describing the observed conditions and requesting a documented response.

Include:

• Project name and roof area
• Dates when the conditions were observed
• Photographs and marked-up roof plans
• The relevant contract or specification provisions, where known
• Any reported leaks or immediate risks
• A request for inspection and corrective-action recommendations
• A reasonable response deadline based on the urgency of the issue

Keep the communication factual. Distinguish between confirmed deficiencies and conditions that still require investigation.

If the project is still under construction, notify the general contractor and owner’s representative as appropriate. Follow the contract’s notice procedures and retain copies of all communications.

10. Contact the Manufacturer if System Compliance or Warranty Is at Risk

If the suspected defects involve seam quality, system compatibility, attachment requirements, or manufacturer-specific details, contact the relevant manufacturer or authorized technical representative.

Ask whether:

• A manufacturer’s field inspection is available or required
• The observed details comply with the applicable installation instructions
• Additional testing is recommended
• Corrective work must be completed by an approved contractor
• A warranty inspection or other documentation is required

Manufacturer involvement does not automatically establish that the work is compliant or that a warranty claim will be accepted. Obtain the manufacturer’s conclusions in writing and clarify the scope of the review.

For example, Johns Manville’s technical and warranty services describe field technical support and final inspections for applicable guaranteed roofing systems. The actual requirements depend on the product, system, and guarantee involved.

11. Develop a Written Corrective-Action Plan

After the defects have been assessed, obtain a written plan identifying what must be corrected, who will perform the work, and how completion will be verified.

The plan should include:

• Each identified defect and its location
• The proposed repair method
• Materials compatible with the installed TPO system
• Relevant manufacturer requirements
• Any additional testing required
• Protection against water intrusion during repairs
• Quality-control and reinspection procedures
• Photographic documentation
• Completion dates and responsible parties

For isolated defects, localized repairs may be appropriate. Widespread seam failures, extensive membrane damage, or recurring installation-related leaks may require more extensive corrective work.

Do not approve a broad repair proposal without understanding which deficiencies it addresses and how the completed work will be verified.

12. Confirm Repairs Before Accepting the Roof

After corrective work is completed, arrange the appropriate follow-up inspection and retain the results.

Depending on the defect and applicable system requirements, verification may include:

• Visual inspection of repaired areas
• Appropriate seam probing after repairs have cooled
• Review of repair photographs
• Verification of flashing and penetration details
• Review of contractor quality-control records
• Additional testing recommended by the qualified professional or manufacturer
• Manufacturer inspection when required for the applicable warranty or guarantee

GAF’s guidance calls for repaired seams to be checked after cooling and identified defects to be corrected in accordance with the system’s repair instructions. See the GAF roofing systems manual.

Do not treat an invoice or a contractor’s statement that the work is complete as a substitute for any required inspection or testing.

13. Protect the Warranty and Preserve Project Records

Improper repairs, incompatible materials, or undocumented modifications can complicate future warranty or guarantee claims.

Retain:

• Original roofing contract and specifications
• Product and system documentation
• Installation and inspection reports
• Photographs of original defects
• Contractor notices and responses
• Manufacturer correspondence
• Corrective-action plans
• Repair invoices and completion records
• Follow-up inspection reports
• Final warranty or guarantee documents

Ask the manufacturer or warranty provider whether the corrective work affects any inspection, notification, or documentation requirements. Do not assume that an installation defect automatically voids a warranty; the applicable documents and circumstances determine the outcome.

GAF also emphasizes the importance of documented inspection and maintenance for applicable guarantee coverage in its article, Inside a Professional Roof Inspection: What to Expect and Why You Need It.

14. Determine Whether Repair or Replacement Is More Appropriate

Not every installation defect requires replacement of the entire TPO roof. The appropriate remedy depends on the number, severity, distribution, and cause of the deficiencies.

Condition	Potential Response
One or two isolated, repairable defects	Targeted repairs and documented verification
Several defects concentrated in one area	Expanded inspection and area-specific corrective work
Repeated seam failures across multiple roof sections	Comprehensive assessment of installation quality and system performance
Widespread attachment or detailing deficiencies	Professional evaluation of the affected assembly and necessary corrective scope
Recurring leaks after previous repairs	Root-cause investigation and reassessment of the repair strategy
Extensive defects that cannot be reliably corrected through localized work	Evaluation of larger-scale reconstruction or replacement

Consider the long-term performance of the roof, the extent of defective work, the costs of repeated repairs, and the warranty implications. A qualified professional should explain why the proposed remedy is appropriate for the actual findings.

15. What If the Contractor Disputes the Findings?

If the contractor disagrees that the work is defective, keep the discussion focused on evidence and the applicable technical requirements.

Recommended steps include:

1. Request the contractor’s written explanation.
2. Identify the specific specifications or manufacturer instructions relevant to the disputed condition.
3. Arrange a joint inspection if practical.
4. Obtain an independent assessment when the dispute remains unresolved.
5. Preserve photographs, inspection records, correspondence, and contract documents.
6. Follow applicable contract notice, dispute-resolution, and warranty procedures.

If the dispute involves substantial financial exposure, project delays, or a potential claim, consider obtaining advice from an appropriately qualified construction attorney before undertaking destructive testing or authorizing extensive replacement work.

Bottom Line

If you find evidence of a bad TPO installation, document the suspected defects, protect the building from water intrusion, compare the work with the approved specifications, and obtain a qualified assessment before deciding on repairs.

Notify the responsible contractor in writing, involve the manufacturer when system compliance or warranty requirements warrant it, and require a documented corrective-action plan. Verify the repairs using the appropriate inspection procedures and preserve the final records.

The goal is not merely to make the roof look acceptable. It is to establish whether the installation meets the applicable requirements and to correct any confirmed deficiencies before they lead to leaks, premature deterioration, or costly disputes.

Related Questions

• What roofing closeout documents should a GC collect before turnover?
• What does a commercial roof observation report include?
• What does a GC need to know about manufacturer warranty inspections on a new commercial roof?

Sources

• GAF — EverGuard TPO/PVC Adhered Roofing Systems Manual
• GAF — Your Guide to TPO Membrane Installation
• GAF — Inside a Professional Roof Inspection: What to Expect and Why You Need It
• Johns Manville — Technical, Guarantee, and Warranty Services
• GAF — Inspecting a Commercial Roof: Is It Time for a Repair or Replacement?

Last reviewed: October 2026

Related Resources

What Is a Commercial Roof Observation Report?

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ShieldLine Roofing can help commercial property owners investigate suspected TPO installation defects, document roof conditions, evaluate repair options, and coordinate corrective work for commercial roofing systems.

Disclaimer: This information is provided for general educational purposes and is not legal, engineering, insurance, or warranty advice. Actual installation requirements depend on the approved project documents, applicable building codes, manufacturer instructions, and warranty terms. Have suspected defects evaluated by an appropriately qualified professional.

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