Ask What's Not Included: A Quality Inspector on the Johns Manville TPO Roofing System and Old Transite Pipe

I review roughly 200 submittals a year before they go out to customers. In our Q1 2024 quality audit, we rejected 12% of first-round submittals. Not because the product brands were wrong. Because the specifications were incomplete.

Here's the thing: I'd rather approve a bid that lists every component, even if the total looks higher, than accept a low bid that doesn't say what's included. The bid that hides scope is never the best bid. Period.

Why I Don't Trust "TPO" as a Complete Spec

People think all TPO roofing systems are basically interchangeable. The assumption is that if the membrane says TPO, the roof will perform. The reality is that a TPO roof is only as good as the system behind it: insulation thickness, fastener pattern, seam details, flashing, edge metal, and the manufacturer's published instructions.

When I specify a roof, I write "Johns Manville TPO roofing system." Not because JM is the only decent membrane available, but because naming the system gives everyone the same reference point. JM publishes detailed data sheets. If a contractor's submittal doesn't match the JM detail, that's a red flag.

I want to say the first time I rejected a submittal like this was on a 2019 retail project, but don't quote me on the exact year. What I remember clearly: the project manager said, "It's the same thing, only cheaper." It wasn't. The cheaper system had a different fastening pattern and no mention of the JM TPO requirements. It would have cost us a $22,000 redo if I had let it through.

(Should mention: the contractor did eventually fix it at their cost. But only after two weeks of emails.)

Old Johns Manville Transite Pipe: The Misconception I Keep Seeing

Old Johns Manville Transite pipe is another example of why vague specs are expensive. It shows up in older buildings, usually as vent, sewer, or water pipe. People think finding Transite pipe means the building is automatically hazardous. That's backwards. Intact Transite is generally low-risk because the fibers are bound in the cement matrix. The risk shows up when someone cuts, grinds, sands, or removes it without testing and containment.

I'm not an environmental consultant, so I can't tell you how to run air sampling or when to call in a hazmat team. What I can tell you from a spec-review perspective is this: if a project involves an older building and the drawings show Johns Manville Transite pipe, the scope needs a defined path. Test it. Then either leave it in place, encapsulate it, or remove it following appropriate procedures. "Contractor to coordinate" is not a plan.

And Then There's Stuff That Doesn't Belong in the Scope

I also pay attention to random line items. I once saw a roofing quote that included replacing a valve stem in a mechanical room. A valve stem. In a roofing bid. That is not a roofing item. It's either scope creep, a typo, or a test to see if anyone is reading.

If you're waiting for me to explain how a swim cap fits in here, that's my point. It doesn't. A valve stem doesn't belong in a roofing spec either. A spec should be specific, but it also needs to be confined to the actual work.

If your search history looks like "johns manville tpo roofing system," "johns manville transite pipe," and "where to buy benjamin moore paint" all in one day, I'm not judging. But "where to buy benjamin moore paint" is a different trade. The advice is still the same: ask for the complete price, including sample chips, delivery, and any other fee that could show up later. That's the paint version of "what's not included."

What a Transparent Quote Should Look Like

The exact format doesn't matter as much as the missing list. A quote for a TPO roof should name:

• The membrane: e.g., 60-mil Johns Manville TPO, color, and reinforcement, meeting ASTM D6878.
• The fastener schedule: pattern, spacing, and type.
• The insulation: layers, thickness, and attachment method.
• Flashing, edge metal, and termination details.
• What will be protected or removed—including any old Transite pipe, even if you think it's "probably fine."
• Exclusions. Written. Not blank.

If a quote doesn't have these, ask why. Then ask again.

But Won't a Detailed Spec Look More Expensive?

Maybe. But the first bid is not the total cost. The contractor who lists the details is telling you what you're buying. The contractor who doesn't is asking you to trust the blank spaces.

I've learned to ask "what's NOT included" before "what's the price." That one question has saved me more money than any discount or rebate. It has also saved me from more than one contractor who thought a valve stem was a roofing item.

Bottom Line

Transparency isn't a personality trait. It's a project-control tool. It's how you catch a missing fastener schedule before it becomes a roof failure. It's how you catch an old Transite pipe assumption before it becomes a safety issue. It's how you catch a random valve stem before it becomes a change order.

This was accurate as of early 2025. Codes and product data sheets change, so verify current requirements before you lock in a spec. The principle doesn't change: know what's included, and know what's not.

That's it. Transparency.