What the report contains
A range for each roof section, the evidence that produced it, the assumptions it rests on and the conditions that would move it either way. The evidence is set out so that a reader can weigh it: what came from documents, what came from observation, what came from testing and what came from inference. Where those sources disagree, the disagreement is recorded rather than resolved silently.
The document is written for a file. It will be read by people who were not on the roof, often after the person who commissioned it has moved on, and sometimes to work out what was known at the time. So the basis of every figure is stated next to the figure.
What the report will not do
It will not produce a single number. A roof does not have one, and a report that supplies one is transferring the author’s assumptions to the reader without showing them.
It will not price the next roof. Replacement cost depends on layer count, wet insulation, access, deck condition and the market at the time of bidding. The report can describe the scope those costs would be applied to.
It will not rate an assembly that was not opened as though it had been. Where cores and moisture testing were out of scope or not permitted, the report says so and states that the range rests on surface evidence, which widens it.
When one is commissioned
Before a capital plan is set, where the roof line is currently an estimate derived from an installation date. During diligence, where the hold period and the roof’s remaining life have to be compared. Before a refinance, where a lender has asked how long the roof has. And before a disposal, where the seller would rather know the answer than discover it in a buyer’s report.
It is also commissioned after a disagreement. Two consultants produce different views of the same roof, and the way to settle it is not a third opinion but a report that shows the evidence behind its number and lets the reader judge.
Common questions
What evidence supports a remaining life estimate?
Four kinds, and a report should show which of them it is relying on.
- The installed system and its age, from documents, permits or a core rather than appearance
- Condition: surface, laps and seams, details, drainage, and whether failures are general
- Assembly evidence: layer count, insulation and deck, from opening or scanning the roof
- History: repair invoices, previous reports, warranty records and recurring work in one area
Details matter more than field area, because commercial roofs fail at details first, and a repair history often reveals more than a single visit. The weight given to each kind should be visible. An estimate resting on a documented date, a core sample and a run of inspection reports is a different statement from one resting on a walk and an assumed age.
Why is remaining life given as a range?
Because the alternative is a single number with hidden assumptions inside it. Remaining life depends on things that have not happened yet and are not observable on the day.
- How the roof is maintained, and how much traffic other trades bring
- What weather arrives, and whether repairs are made promptly or deferred
- A useful range names what would move it toward the short end
- Deferred repairs, spreading moisture, continued equipment work on the roof
- And what would move it long, usually maintenance and prompt detail repairs
That lets a reader use the figure conditionally, which is how it will be used anyway. Treat a precise single figure with suspicion, particularly one from a visual inspection with no testing and no documents. It suggests a method that stopped at the surface.
What can a remaining life figure not be used for?
It cannot tell you when the roof will leak. It describes the service life of the assembly, not the date of the next incident.
- Leaks come from discrete failures at details, storm damage and other trades
- A roof with years of estimated life left can leak next month at a pipe boot
- It is not a replacement cost, which turns on layers, wet insulation, access and deck
- It is not a warranty position, which the documents and the maintenance record set
- It is not a substitute for inspection
The estimate assumes maintenance that only happens if someone does it, so a roof with several years left still needs to be looked at. Where a report is being used to justify deferring inspection, it is being used backward.
How do core samples and moisture readings change the figure?
More than anything else in the scope, which is why a report written without them should say so plainly. Cores and a survey establish what is under the membrane, where the decisive variables sit.
- Layer count decides whether the next roof is an overlay or a tear off
- Insulation condition shows whether water has already spread through the assembly
- Wet insulation moves well beyond the opening that admitted it and does not reliably dry
- Deck condition decides whether the work is a roof project or a structural one
A roof with a sound deck, dry insulation and one system on it supports a longer range than the surface alone would justify, and a roof with extensive trapped moisture supports a much shorter one however the membrane looks. Where testing was out of scope, the report says the assembly was not opened.
How often should a remaining life figure be revisited?
Whenever the assumptions behind it change, and on a regular cycle regardless. The figure is conditional on maintenance, on prompt repairs and on nothing unusual happening to the roof.
- A severe storm
- A leak, particularly a recurring one in the same area
- Work by another trade, including solar, telecoms or mechanical installation
- Any repair that opened the assembly and revealed something the estimate missed
A roof that went years without an inspection, took equipment work from several trades and had a repair deferred through a season is not on the path the estimate assumed. For a portfolio, update the figures from the inspection cycle rather than commissioning separate exercises, because a dated series shows direction and direction is what a single visit is trying to infer.