A commercial leak is a tracing problem before it is a repair.

On a pitched roof, water mostly runs downhill from where it got in. On a low-slope roof it travels sideways between membrane and deck, along insulation joints and deck flutes, and appears through the ceiling somewhere else entirely. That is why commercial repair is its own discipline, and why the first part of the visit is spent looking rather than cutting.

Compare this on your roof

A low-slope commercial roof at dusk, mechanical curbs silhouetted against a warm horizon.

At a glance

The system, before the sales pitch.

Specification first. Every row below is a property of the system, not a claim about a product line.

Trace before you cut: The stain on the ceiling tile is where the water finished, not where it started. On a metal deck it can run the length of a flute before it drops. We work back from the interior evidence to a plausible entry point, and say how confident we are in it.
Most leaks are at an interruption: Curbs, drains, pipe penetrations, parapet tie-ins and the seams around rooftop equipment account for most of what gets reported as a roof leak. The open field is usually the innocent party, which is why the open field is not where the search begins.
The repair has to match the roof: A patch in the wrong material is a leak with a delay on it. Identifying the existing membrane, then using compatible material and the correct joining method, is what separates a repair from a return visit at the same coordinates.

A low-slope commercial roof field with mechanical curbs, a drain and welded seam lines.

How the system behaves

Performance is an assembly, not a product name.

A metal equipment curb on a granulated cap-sheet membrane roof, the membrane flashing dressed up the base of the curb.

Tie-ins are where repairs fail

The junction between new patch and old membrane is the weak line, and preparation decides it: how clean the surface came up, whether the old sheet has weathered past the point of bonding, and how far the overlap runs. Where the existing membrane will not take a bond, the honest answer is a larger section replaced, not a smaller one stuck on.

Keeping a manufacturer warranty intact

Where a manufacturer system warranty is in force, unauthorised work on the roof can void it. These warranties — the no-dollar-limit kind and the material-only kind alike — carry conditions about who may work on the roof, what materials may be used, and what must be reported and when. We ask for the warranty document before repair work is scoped, because that document sets the constraints.

Working over people who are still working

An occupied building sets the terms: access route, working hours, hoisting, odour and fumes, fire watch where heat is used, protection for whatever sits below an open detail, and enough time at the end of each day to leave the roof watertight. Those items belong in the scope, not in a conversation on the first morning.

Choose a starting point

Match the next step to the condition.

A short, non-diagnostic guide for working out what kind of assessment conversation to prepare for.

What best describes the property today?

Decision support

Choose a starting point.

Four situations, and the sensible next move for each. It does not diagnose a roof, decide insurance coverage, or stand in for somebody looking at the property.

What the next step actually is
What to have ready before anyone arrives
What we will not ask you to do

Questions

Useful answers, without overpromising.

Why does the leak seem to move around the building?

Because water runs laterally under a low-slope membrane before it finds a way down. Two stains at opposite ends of a bay can share one entry point, and one stain can have two sources. That is the reason tracing comes before repair.

Does the search have to wait for rain?

Usually not. Evidence in the insulation, staining at the deck and the condition of the details tell most of the story. Where they do not, controlled water testing on a suspected area is the next step, run one detail at a time so that a positive result actually means something.

When does repair stop being the right answer?

When one roof is generating repeated calls in different places, when the insulation is wet across a wide area, or when the membrane has weathered past the point where a patch will bond. Past there, repair spending is buying time on a decision that has already been made.

The last contractor patched it and it came back. Is that their fault?

Not necessarily, and two things are worth separating. A patch made in the wrong material, or onto a surface that would never have bonded, is a workmanship problem. A patch made correctly at a plausible entry point on a roof that has more than one is an incomplete diagnosis, which is ordinary on a low-slope roof and should have been said out loud at the time. What distinguishes them afterwards is whether the first visit recorded a theory or only an invoice.

Assessment request

Tell us what is happening at the property.

Short, routing-only questions. Nothing here asks you to diagnose the roof yourself.