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Home/Service Areas/Louisiana/LaPlace/Commercial Roof Leak Detection

Commercial Roof Leak Detection in LaPlace, LA

Big Easy Roofing detects commercial roof leaks across LaPlace and the east bank of St. John the Baptist Parish. On a low slope roof water enters at a breach in the membrane, tracks sideways, and shows up inside a long way from where it got in. When it shows up, and in which kind of rain, is part of the evidence.

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63.1 inchesAverage annual rainfall in the parish plan
Two kinds of rainFrontal systems and afternoon storms
ASTM D7877 and D8231Standards behind the ELD method
Moisture surveyOn the inspections page

LaPlace commercial roof leak detection at a glance

A commercial leak is found at the breach in the membrane, not by following the drip inside. Electronic leak detection and the controlled flood test both do that. The parish Hazard Mitigation Plan puts average annual rainfall for the area at 63.1 inches, and the kind of rain a leak shows up in is part of the history we take.

The two methods

ELD and controlled flood

Electronic leak detection (ELD) puts a small voltage across the membrane and locates the breach where current passes through. The controlled flood test dams an area, floods it and watches the interior. ELD is quicker on a large open roof; the flood test is definitive on a small area where ELD cannot be used.

The standards behind ELD

ASTM D7877 and D8231

ASTM D7877 is the standard guide for electronic methods for detecting and locating leaks in waterproof membranes. ASTM D8231 is the standard practice for a low voltage electronic scanning system. The report names the method and the standard; the edition is confirmed when the scope is written.

What the parish plan says about rain

63.1 inches a year

The St. John the Baptist Parish Hazard Mitigation Plan says "Average annual rainfall for the area is 63.1 inches." For Louisiana it describes heavy rain from slow moving fronts in the cooler months and from isolated thunderstorms in summer and autumn.

Which office covers you

St. John the Baptist Parish

Leak detection is our own diagnostic of an existing roof. Any repair or re-roof scoped from it goes to the parish Permit Division on (985) 651-5565 at 1811 W. Airline Highway in LaPlace, through MyGovernmentOnline or in person, and whether a scoped repair needs a permit is confirmed there.

What decides scope after we find it

The moisture survey

Finding the breach is one question; how much insulation below it is wet is another. The moisture survey is on our commercial roof inspections page, and on a real leak call the two usually run together.

The interior drip is a starting point

Not the location

On a low slope roof water enters at a breach, tracks along the top of the deck or through wet insulation, and appears inside at a point that can be a long way off. The drip tells us the leak is real; it does not tell us where it is.

This page addresses roofing on buildings treated as nonresidential for licensing and code purposes. Mixed use buildings and residential multifamily need their own classification and code review.

The plan quotes on this page are from the parish 2021 Hazard Mitigation Plan Update. The plan describes rain and flooding; it does not discuss roof leaks, and what we take from it for a leak call is labelled as our reading. Leak detection is priced on the roof and the method rather than a published range, so call Big Easy Roofing to arrange a visit.

Electronic leak detection against the controlled flood test

The two methods answer the same question by different physics, and each has cases where the other is the right one. The membrane type, the size of the area and whether the roof can carry the weight of a flood decide between them. The table sets out how each works and where each fits.

MethodHow it worksWhere it fitsWhere it does not
Low voltage scanning (ASTM D8231)A conductive wire is laid around the test area, a small voltage is applied to the wetted membrane, and a scanner finds where current passes through itLarge open low slope roofs with an electrically insulating membrane, where the scanner can reach the areaConductive membranes and membranes with a foil facer. Suitability on a given membrane is checked against the manufacturer's position first.
High voltage spark testing (covered by ASTM D7877)A wand carrying a higher voltage is passed over a dry membrane, and a breach registers as a sparkSmaller areas and details around penetrations on compatible membranesContinuous large area scanning, and any membrane the manufacturer says the method may damage
Controlled flood testA dam is built around the test area, water is added to a controlled depth, and the interior is watched for water coming throughA defined area where the leak is suspected, where the structure can carry the loadLarge open areas, structures that cannot take the load, and spaces below that cannot take water
Both togetherELD to narrow the breach down across the area, then a flood test on that zone to confirmWhere the finding matters enough to confirm and the roof and the tenant allow bothA first pass call where the priority is to stop water; ELD alone often finds enough to move to repair

The highlighted row is a common first pass on a large open commercial roof. Where ELD is the wrong method, the controlled flood test is the alternative. Either way the target is the breach in the membrane; the wet insulation question runs to the moisture survey.

What leak detection is, and what it is not

A leak detection visit is a diagnostic that finds where water gets through a commercial membrane. It is not a code inspection, it is not a moisture survey, and it is not an insurance judgement. Work scoped from it is a separate matter for the parish Permit Division.

Not a code inspection

That belongs to permitted work

Louisiana requires every parish or municipality that issues construction permits to permit and inspect reroofing, under La. R.S. 37:3737(I), originated by Act 239 of 2025 and recodified by Act 881 of 2026. For buildings other than one and two family dwellings the code named is International Building Code Chapter 15. Our leak report is a separate document.

Not a moisture survey

That is on the inspections page

Leak detection finds where water enters the membrane. A moisture survey measures how much of the insulation below is wet. They are two questions with two sets of methods.

Who confirms the scope

St. John the Baptist Parish

The Permit Division on (985) 651-5565 at 1811 W. Airline Highway in LaPlace, 8 am to 4:30 pm Monday to Friday excluding government holidays. Applications go through MyGovernmentOnline or in person. Whether a scoped repair needs a permit is confirmed there.

Not an insurance judgement

A separate role

The report describes the breach, the water path and the method used. What your insurer does with it is between you, your insurer and any public adjuster you engage. We do not interpret a policy or predict a claim.

What the report contains

The breach located on a roof plan, photographs close up and in context, the method used and the ASTM standard it sits under, and a note on where the follow-up work points. Where the finding sits over wet insulation, that is marked and the moisture survey is recommended.

Our practice, not a parish rule: the report also records when the leak shows up inside, in what kind of rain and after how long, as the owner or tenant describes it.

What ELD needs to work

Three things: an electrically insulating membrane, a conductive path below it through the deck or wet material, and access to lay the wire around the test area. Where one is missing, ELD can read "no breach" when there is one.

The controlled flood test is the alternative in those cases, on an area small enough to dam and a structure that can carry the water.

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What the parish plan says about rain, and why a leak call asks

The St. John the Baptist Parish Hazard Mitigation Plan, updated in 2021, puts average annual rainfall for the area at 63.1 inches. It describes two patterns for Louisiana: heavy rain from slow moving fronts in the cooler months, and isolated thunderstorms, often on warm afternoons, in summer and autumn.

The parish figure

The plan says "Average annual rainfall for the area is 63.1 inches." It adds that the parish "is susceptible to the normal weather dangers, such as thunderstorms and flooding, ...", and that "The majority of the industrial and commercial areas are located along the Mississippi River corridor."

You can read the plan on the parish Hazard Mitigation Plan Update page.

Two kinds of rain

Writing about Louisiana as a whole, the plan says "Louisiana can have high rainfall totals at any time of day or year." In the cooler months "slow-moving frontal weather systems produce heavy rainfalls ...", while summer and autumn bring "major precipitation in isolated thunderstorm events (often on warm afternoons) ...".

It adds that the fronts "often stall while passing over the state, occasionally producing rainfall totals exceeding ten inches within a period of a few days."

What that means on a leak call

Our reading, not the plan's: a small breach can let little through in a short afternoon storm and much more in a front that stalls and rains for days, so the same roof can look sound in one season and leak in the next. The plan does not say this; it describes the rain.

Our practice, not a parish rule: we ask which kind of rain the leak shows up in and how long after it starts, and we record it. Where waiting for the right rain is not an option, a controlled flood test puts water on a defined area on our schedule.

Big Easy Roofing Process

Four steps. The method is picked against the roof, the membrane and the tenant before any test is set up, because either method used in the wrong case can read "no leak" when there is one.

A roofer running an electronic leak detection scan on a LaPlace commercial low slope roof
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01

Take the history and walk the roof

Where water appears inside, in what kind of rain and after how long, and what the roof above looks like: membrane type, area, drains, penetrations and structure.

02

Pick ELD or the controlled flood

ELD on a compatible large area membrane, the flood test on a defined smaller area or a membrane ELD cannot read, or both where the finding needs confirming.

03

Run the test to the named standard

ELD to ASTM D8231 for low voltage scanning or D7877 for the high voltage method, with the dam, the depth and the interior watch photographed on a flood test.

04

Report and route the next step

The breach on the roof plan, the method and standard, photographs and the rain history. A wet insulation zone goes to the moisture survey; a repair scope goes to the commercial roof repairs page, and its permit question goes to the Permit Division.

Everything else we do in LaPlace

The rest of the Big Easy Roofing services available in LaPlace, each with its own page and written scope. The moisture survey behind a leak call is on the commercial inspections page, and the repair once the breach is found is on the commercial roof repairs page.

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LaPlace Commercial Roof Leak Detection FAQs

How a commercial leak is found, why the drip inside is a starting point rather than a location, and what the parish plan says about the rain that brings it out.