Summary

The success of any commercial construction project depends heavily on the quality of your subcontractors—especially the roofing sub. In Indiana, flat roof failures often come from poor installation, weak flashing, or shortcuts taken by inexperienced subs. This guide gives general contractors a complete checklist for verifying insurance, certifications, workmanship standards, crew quality, safety protocols, warranties, communication habits, and red flags. Use this framework to protect your deadlines, your margins, and your reputation on every project.

Introduction: Why Choosing the Right Roofing Sub Matters More in Indiana

If you’re a general contractor in Northeast Indiana, you already know that flat roofs are one of the most common sources of callbacks, warranty disputes, leaks, and construction delays. Indiana’s climate amplifies these problems—harsh winters, heavy snow loads, humidity, and freeze–thaw cycles expose poor workmanship quickly.

Hiring the wrong roofing subcontractor doesn’t just waste money—it damages your reputation with clients and complicates project timelines. On the other hand, hiring the right sub can make you look like a hero, keep schedule delays to a minimum, and reduce warranty claims for years.

This complete vetting checklist is designed specifically for Indiana contractors who need high-performing flat roof subcontractors they can trust.

Verify Licensing, Insurance, and Certifications

Before you ask about pricing or timelines, verify credentials. Roofing is one of the highest-risk trades on any job site, and the wrong paperwork puts liability directly on you.

Documentation to Request Immediately

• Commercial liability insurance
  
  
  

• Workers’ compensation coverage
  
  
  

• Umbrella or excess liability (recommended for large jobs)
  
  
  

• Additional insured endorsement naming your company
  
  
  

• State/county license (where required)
  
  
  

A roofing sub without proper insurance is a liability bomb waiting to go off. Never proceed without documentation.

Manufacturer Certifications Matter

Flat roofs require product-specific training for warranties to be valid. Ask for:

• Carlisle, Firestone, GAF, Versico, or Johns Manville certifications
  
  
  

• TPO/PVC welding certifications
  
  
  

• EPDM system training
  
  
  

• Coating manufacturer approval
  
  
  

If a sub is not certified, they cannot offer meaningful warranties for single-ply roofs—and you’ll be left with the liability.

Evaluate Experience With Your Specific Project

Not all roofing subs can handle every job. A sub who only installs EPDM might not be equipped for PVC welds. A sub who mostly handles residential work should not be touching a 100,000 sq. ft. industrial building.

Questions to Ask

• “Which roofing systems do you specialize in?”
  
  
  

• “How many TPO/PVC installs have you completed in the last 12 months?”
  
  
  

• “Do you have experience with large commercial or industrial buildings?”
  
  
  

• “How do you design and install tapered insulation systems?”
  
  
  

Red Flags

• They say “we install everything the same way”
  
  
  

• They don’t differentiate between commercial and industrial
  
  
  

• They avoid talking about welding, flashing, or drainage
  
  
  

Your subcontractor should bring expertise to the table—not broad generalities.

Demand a Detailed Scope of Work Upfront

A vague roofing proposal is a guaranteed change-order nightmare. Skilled subcontractors give precise, detailed scopes of work (SOW).

A professional scope includes:

• Exact membrane type, thickness, and brand
  
  
  

• Insulation type, thickness, and R-value
  
  
  

• Tapered insulation layout, crickets, and slopes
  
  
  

• Fastener patterns
  
  
  

• Flashing and curb details
  
  
  

• Drainage plan
  
  
  

• Penetration count
  
  
  

• Safety plan
  
  
  

• Cleanup and disposal plan
  
  
  

• Project timeline
  
  
  

A complete, transparent scope protects you from cut-corner workmanship and budget overruns.

Review Past Projects and Request Photo Documentation

A roofer’s past work tells you everything you need to know about their skill and habits.

Ask for photos of:

• Insulation layout and slope creation
  
  
  

• Welded seams on TPO and PVC
  
  
  

• Flashing around HVAC curbs
  
  
  

• Perimeter edge metal
  
  
  

• Before/after comparisons
  
  
  

• Large commercial jobs similar to yours
  
  
  

A roofing sub who refuses to show photos is hiding something.

Ask for references

• Verify job size
  
  
  

• Ask about scheduling reliability
  
  
  

• Ask whether there were callbacks
  
  
  

• Ask if they worked clean, safe, and on-time
  
  
  

Trustworthy subs are proud to show off their work.

Inspect Their Flashing and Drainage Standards

Flashing and drainage are the two biggest failure points in flat roofing—and the easiest way to identify a quality sub.

Critical flashing questions

• “What is your minimum flashing height?”
  
  
  

• “How do you reinforce corners?”
  
  
  

• “Do you use termination bars on wall transitions?”
  
  
  

• “What is your curb flashing standard?”
  
  
  

Drainage essentials

• Slope to drains must meet ¼” per foot
  
  
  

• Crickets must be installed behind HVAC units
  
  
  

• Scuppers must be properly sized for Indiana code
  
  
  

• They must verify deck condition and correct low spots
  
  
  

If a sub avoids talking about flashing or drainage, they are not qualified.

Evaluate Crew Quality, Safety Standards & Training

A roofer is only as good as the crew working for them.

Crew Quality Questions

• Are workers W-2 employees or 1099 laborers?
  
  
  

• How long has the core crew been together?
  
  
  

• Are installers system-certified or just helpers?
  
  
  

• How many crew members will be on your job?
  
  
  

Safety Standards

• Site-specific fall protection plan
  
  
  

• Daily toolbox talks
  
  
  

• OSHA 10/30 certifications
  
  
  

• Proper harness usage
  
  
  

• Perimeter flags and warning lines
  
  
  

Well-trained crews work safer, faster, and with fewer mistakes.

Understand Their Warranty Practices

Warranties are crucial for commercial projects. Indiana contractors must know exactly what the sub is offering.

Three warranties to understand

1. Material warranty
   From manufacturer — only valid if installer is certified.
   
   
   

2. Workmanship (labor) warranty
   From the subcontractor — protects against installation defects.
   
   
   

3. NDL (No Dollar Limit) warranties
   Premium option — covers total cost of repair or replacement.
   
   
   

Make sure the sub:

• Explains what voids the warranty
  
  
  

• Provides proper documentation
  
  
  

• Installs exactly to manufacturer specs
  
  
  

Warranties are worthless if installation doesn’t meet standards.

Communication & Project Management Expectations

You can tell a great sub from a bad one based on communication alone.

A professional roofing sub provides:

• Daily progress updates
  
  
  

• Photo documentation
  
  
  

• Weather-related alerts
  
  
  

• Clear change order process
  
  
  

• Accurate timelines
  
  
  

• Immediate communication when issues arise
  
  
  

Red Flags

• Disappearing for days
  
  
  

• Only communicating when problems occur
  
  
  

• Misleading completion dates
  
  
  

• Not reporting hidden damage discovered during tear-off
  
  
  

Good subs make your job easier. Bad subs make it a nightmare.

Major Red Flags That Mean “Do Not Hire This Sub”

If you see ANY of the following, walk away immediately:

• Significantly lower pricing than competitors
  
  
  

• No insurance documentation
  
  
  

• No manufacturer certifications
  
  
  

• Avoids discussions about drainage or tapered insulation
  
  
  

• Claims “we can install anything”
  
  
  

• Refuses to provide references
  
  
  

• Offers unrealistic timelines
  
  
  

• Sloppy or nonexistent photo evidence
  
  
  

• No written scope of work
  
  
  

Flat roofs fail from poor installation—not poor materials. These red flags point to future headaches.

Conclusion: Use This Checklist to Protect Your Project and Reputation

Hiring the right flat roof subcontractor is one of the most important decisions an Indiana contractor can make. A skilled, reliable roofing sub protects your deadlines, reduces callbacks, keeps warranty claims to a minimum, and strengthens your reputation with clients.

By following this checklist — verifying credentials, reviewing workmanship, evaluating communication habits, inspecting drainage standards, and identifying red flags — you ensure that your subcontractor is an asset, not a liability.

High-quality roofing subs save your company time, money, and stress. Use this guide every time you hire one.