What a Central Ohio Commercial Roof Estimate Should Include

Why Two Estimates on the Same Building Differ So Much

It is normal to get quotes on the same Columbus building that are tens of thousands of dollars apart. That gap is almost never about profit margin. It is about scope. One contractor is tearing the old system off down to the deck and replacing wet insulation. The other is laying a new membrane over the top of what is already there. Both are legitimate approaches in the right situation, but they are not the same job and they will not last the same length of time. Until every proposal in front of you describes the same scope, you are not comparing prices at all.

What the Scope Has to Name

A proposal you can actually evaluate names all of the following. If any of these are missing, ask before you sign.

• The membrane and its thickness. Not just “TPO” but the mil thickness. A 45 mil and a 80 mil membrane are very different products with very different service lives.
• The insulation and its R value. Ohio energy code has minimum requirements on a full tear off. The proposal should state what is going down and how thick.
• How it is attached. Mechanically fastened, fully adhered, or ballasted. This drives wind performance and cost.
• Tear off or recover. Whether the existing system is coming off, and what happens if saturated insulation turns up underneath.
• The deck condition allowance. What the contractor does, and what it costs, when rusted steel or rotted wood decking is found after the old roof is removed.

Flashing and Penetrations Are Where Roofs Actually Leak

Flat roofs rarely fail in the middle of the field. They fail at the edges and at everything that pokes through them: curbs, drains, vents, pipes, and the roof to wall intersections. A serious proposal spells out how each of those gets treated, including new pipe boots, new curb flashing, and new termination bars at the walls. A proposal that says “flash as needed” is leaving itself room to reuse tired detail work on a brand new roof. That is the most common way an expensive commercial roof starts leaking early.

Drainage and Ponding Water

Water that is still sitting on a low slope roof forty eight hours after a Central Ohio storm is a problem, not a quirk. Ponding adds weight, accelerates membrane aging, and voids a lot of manufacturer coverage. If your building ponds now, the estimate should say what is being done about it, whether that is tapered insulation, additional drains, or reworking the existing ones. A new membrane laid over an unresolved drainage problem inherits the problem.

Recover Versus Tear Off

A recover, laying the new system over the old one, is cheaper and faster and is genuinely the right call on some buildings. But Ohio code limits you to a single recover, and a recover traps whatever moisture is already in the existing insulation. If the proposal recommends a recover, it should also say how the existing system was checked for trapped moisture. A core sample or an infrared scan is the honest way to answer that question. “It looked fine from up there” is not.

Read the Warranty Language on the Estimate Itself

The proposal will usually name a warranty term in years. That number on its own means very little until you know who is standing behind it and what it excludes. Before you sign, get clear on which part is manufacturer coverage and which part is the contractor’s own, because they cover completely different failures. We cover that split in detail in our guide to commercial roof warranties.

Questions Worth Asking Before You Sign

• Who is physically doing the work, your employees or a subcontracted crew?
• What happens to the price if wet insulation or bad decking is found mid job?
• How is the building protected and secured overnight during the project?
• What does the manufacturer require from me afterward to keep coverage valid?
• Can I see a building of similar size and system that you completed locally?

If you are still deciding between membrane types before you get to this stage, our comparison of TPO vs EPDM covers how the two systems differ on energy, seams, and repairs.