Why does the wet film differ from the dry film?

Because part of what goes on is carrier that evaporates. The share that stays is the volume solids, so a coating at 55 percent volume solids laid at 36 mils wet cures to about 20 mils dry. That is why a scope states the wet rate as well: it is what a gauge can check while the work is happening, before the film has cured.

How do I work out how much material a roof needs?

A US gallon is 231 cubic inches, so at one thousandth of an inch it covers 1,604 square feet. Multiply that by the volume solids and divide by the specified dry film to get coverage per gallon. At 55 percent solids and 20 mils dry that is about 44 square feet a gallon, or roughly 2.3 gallons per hundred square feet.

Is the coverage figure on the datasheet reliable?

Treat it as a ceiling rather than a plan. Datasheet coverage is theoretical and assumes a smooth surface with no loss. A granulated cap sheet, an aged porous surface or a windy day all take more, so a bid built on the theoretical figure alone tends to run short of material before it runs short of roof.

Two quotes are nearly the same price. How do I choose?

Put the specifications side by side rather than the totals. Ask each bidder for the product name, the specified dry film, the volume solids, the wet rate and what preparation is included. Quotes that look identical at the bottom line can turn out to be buying materially different quantities of material once those five lines are filled in.

Why is one quote offering a longer warranty?

Often because it is a thicker specification rather than a better brand. Manufacturers issue terms against a stated dry film and a stated preparation, and length can also turn on the system, the substrate and any inspection conditions attached. Compare the specifications before you compare the years, and ask what each term is written against.

Does the contractor have to be approved by the manufacturer?

For many systems, yes, and it is worth asking before work is booked rather than after. A manufacturer system warranty is often issuable only by a contractor approved for that system, and approval is not something that can be applied retrospectively to a roof that has already been coated.

Should I coat my roof or replace it?

That is a survey question and it is answered on the roof coating page rather than here. The short version is that a coating goes over a roof that is still sound and cannot rescue one that is not, so what is under the membrane decides it. Wet insulation is the usual disqualifier, and how it is found is covered on the commercial roof inspections page.

Does a commercial coating need a permit in East Baton Rouge?

A coating over a covering that stays in place is maintenance rather than the re roofing that La. R.S. 37:3737(I) makes permitted and inspected, so it is normally outside it. Where the scope turns into a re covering the position changes, and we confirm it with the parish before starting rather than assuming either way.

What would a permit cost if one is needed?

East Baton Rouge prices commercial permits on construction valuation rather than by trade: $5 per thousand up to $100,000, then $500 plus $4 per thousand to $500,000, then $2,100 plus $1.50 per thousand above that, with a $100 minimum. A separate plan review fee runs at $3 per thousand and a $25 technology fee applies to every permit. Figures read from the parish fee page on 3 September 2026.

Home/Service Areas/Louisiana/Baton Rouge/Commercial Roof Coating

Commercial Roof Coating in Baton Rouge, LA

Big Easy Roofing coats commercial roofs across Baton Rouge and East Baton Rouge Parish. Two coating quotes at the same price per square foot can be two different products at two different thicknesses. The number that separates them is the dry film, and it is the line a quote can most easily leave out.

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Service

City

Dry film milsWhat you are buying

East Baton RougePermits a reroof

1,604 sq ftPer gallon at one wet mil

WarrantyWritten on thickness

Baton Rouge commercial roof coating at a glance

A commercial coating is a liquid membrane applied over a roof that is still sound. It is specified on dry film thickness in thousandths of an inch, not on how many coats go on, because thickness is what the manufacturer writes the warranty against and what makes two quotes comparable to each other.

What you are buying

Dry film mils

A mil is one thousandth of an inch. The scope names the dry film the finished system has to reach, and everything else on the quote is a means of getting there. Two coats of a thin product is not the same purchase as two coats of a thick one.

Who issues the permit

East Baton Rouge Parish

The parish is the permitting authority for most Baton Rouge addresses. A coating applied to a sound existing roof is maintenance rather than the re roofing the 2025 rule covers, and where a job turns into a re covering we confirm the position with Permits and Inspections first.

The constant behind it

1,604 sq ft

A US gallon is 231 cubic inches, so spread one thousandth of an inch thick it covers 1,604 square feet. A theoretical coverage figure on a datasheet comes from that number reduced by the volume solids and the specified thickness.

Mils, not coats

The comparable number

A quote reading two coats states nothing you can check. A quote reading a named product at a stated dry film, with the volume solids and the wet rate, can be put beside another one and actually compared.

What the warranty rides on

Thickness and prep

Coating manufacturers issue warranty terms against the specified dry film and the surface preparation, and frequently against an approved applicator as well. Term length can turn on the system, the substrate and the inspection conditions too, so ask what a given term is written against rather than reading the years on their own.

The figure to distrust

Theoretical coverage

Datasheet coverage assumes a smooth surface and no loss. A granulated cap sheet, a porous aged surface or a windy application all take more than the sheet says, so treat it as a ceiling rather than as a plan.

A coating quote is one of the least comparable documents in commercial roofing. Two bidders can put almost the same price per square foot on the same building and be offering different products at different thicknesses over different amounts of preparation, and nothing on either page tells the reader which is which. That is not usually dishonesty. It is that the one number that would settle it, the dry film thickness the finished system has to reach, is not a number either side has been asked for.

So this page is about the arithmetic rather than about whether your roof should be coated. Big Easy Roofing writes a commercial coating scope naming the product, the specified dry film, the volume solids, the wet rate that produces that dry film and the preparation, and the reason all five appear is that any one of them missing makes the other four unverifiable. Whether the roof is a candidate for a coating at all is a different question, answered by a survey and set out on the roof coating page, and finding wet insulation before anything is specified is covered on the commercial roof inspections page.

Dry film, wet film and what a gallon actually covers

The whole calculation runs off one constant. A gallon spread at one thousandth of an inch covers 1,604 square feet, so dividing that by the specified dry film and multiplying by the volume solids gives the coverage. Worked here at 55 percent volume solids, which is a common figure rather than a universal one.

Specified dry film	Wet film needed	Theoretical coverage	Gallons per 100 sq ft
15 mils dry	About 27 mils wet	About 59 sq ft per gallon	About 1.7 gallons
20 mils dry	About 36 mils wet	About 44 sq ft per gallon	About 2.3 gallons
25 mils dry	About 45 mils wet	About 35 sq ft per gallon	About 2.8 gallons
30 mils dry	About 55 mils wet	About 29 sq ft per gallon	About 3.4 gallons
A quote reading two coats	Not stated	Not stated	Cannot be worked out

Worked at 55 percent volume solids, so a product at a different solids content gives different figures and the datasheet governs. These are theoretical coverages on a smooth surface with no loss, and a real roof takes more, which is why they are a ceiling rather than a plan. No row here is a recommendation: the right dry film comes from the system and the manufacturer, not from a table. Call (504) 800-8196 for a scope with the thickness, the solids and the wet rate written into it.

What the warranty rides on, and who permits the work

A coating warranty is issued against the specification rather than against the brand on the pail, so the thickness and the preparation decide the term. The permit position is separate and follows whether the covering is being replaced, which on a coating over a sound roof it is not.

Warranty term

Rides on the spec

Manufacturers write the years against a specified dry film and a stated preparation, among other conditions. Two quotes offering different terms can be the same chemistry at two thicknesses, so compare the specifications before comparing the terms.

Approved applicator

Often a condition

Many coating warranties are issuable only by a contractor the manufacturer has approved for that system. It is worth asking early, because it is not something that can be added after the roof is coated.

Who issues the permit

East Baton Rouge Parish

For Baton Rouge and the unincorporated parish. The City of St. George took applications filed on or after 16 October 2024, and Baker, Zachary and Central run their own, so the address decides which office covers the building. We confirm it before filing.

How the fee is set

On construction valuation

There is no flat reroof fee in the East Baton Rouge schedule. A commercial permit is calculated per thousand dollars of construction valuation, with a separate plan review fee calculated the same way, read from the parish fee page on 3 September 2026.

Is a coating a reroof

It depends on what is being done, not on what the invoice calls it. La. R.S. 37:3737(I), added by Act 239 of 2025, makes a reroof a permitted and inspected job in Louisiana. A coating applied over a covering that stays in place is maintenance rather than a covering replacement, so it is normally outside that.

The line is not always obvious, though. The 2021 International Building Code with Louisiana amendments treats a new protective coating over an existing coating as one of the routes by which a roof may be recovered without tear off, which is why the scope matters more than the word. Where a job turns into a re covering we confirm the position with East Baton Rouge Permits and Inspections before it starts. The commercial re roofing page sets out that code test in full.

What the fee bands are

Read from the parish fee page on 3 September 2026, and quoted here in the same form as on the commercial roof repairs page so the two agree. Up to $100,000 of construction valuation the building permit runs at $5 per thousand with a $100 minimum. Over $100,000 to $500,000 it is $500 plus $4 per thousand above $100,000. Above $500,000 it is $2,100 plus $1.50 per thousand above $500,000.

A separate plan review fee runs at $3 per thousand with a $100 minimum up to $500,000, and a $25 technology fee applies to every permit. Those are parish charges on the permit, not the cost of the work, and the parish publishes no roofing line item at all.

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Big Easy Roofing Process

A commercial coating is specified before it is priced, because the thickness and the preparation are what the price is a consequence of. Four steps, and the written scope at the end names every number on this page.

Roofer measuring coating thickness on a commercial low slope roof in Baton Rouge

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Survey the roof first

The roof is walked and assessed before any product is named. If the insulation is wet or the covering has failed, the honest answer is not a coating, and we say so at this stage rather than after the pails are on site.

Name the system and the dry film

The scope states the product, the specified dry film thickness the finished system has to reach, the volume solids and the wet rate that produces it. Those four lines are what make the quote checkable against anybody else.

Prepare, then apply in stages

Cleaning, repairs and primer where the substrate needs it, then the coating applied in stages with the wet film measured as it goes on rather than counted in coats.

Hand over the numbers

The finished job is documented against the specification it was written to, so the thickness the warranty rides on is recorded rather than assumed.

Everything else we do in Baton Rouge

The rest of the Big Easy Roofing services available in Baton Rouge, each with its own page and written estimate. This page covers how a commercial coating is specified. Whether your roof is a candidate at all is answered on the roof coating page, and finding wet insulation on the commercial roof inspections page.

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