Which elastomeric chemistry is right for my roof?

It follows from the substrate first and then the leading failure mode. Where water stands after rain, silicone typically tolerates it better than water dispersed acrylic. Where the roof drains and sun is the main concern, acrylic is often the answer. Heavy foot traffic, especially over spray polyurethane foam, points to polyurethane.

What standards do the coating materials meet?

Section 1509.2 of the International Building Code text we read says roof coating materials shall comply with Table 1509.2. That table lists ASTM D6083 for acrylic, ASTM D6694 for silicone and ASTM D6947 for moisture-cured polyurethane. We name the standard in the scope.

Why not silicone on every roof?

Because silicone usually narrows future re-coat options to silicone. On a roof that drains fully, that is a compatibility cost for a ponding benefit the roof never uses. On a roof that ponds, it is normally the right trade.

What roof types does the parish form list?

The Assessor's Office page of the St. John the Baptist Parish Commercial Permit Application lists Composite, Galvanize, Painted Metal, Aluminum, Shingle and Slate, with one to be circled. The page cites R.S. 47:1957(B) as amended by Act 829.

Does a coating job need the Assessor page?

The form lists the Assessor page as required for renovations only, and it does not say whether a coating counts. We ask the Permit Division on (985) 651-5565 for the specific scope rather than assume.

My roof is metal, does that change the coating?

It changes the preparation. On galvanized, painted or aluminum metal the fasteners, laps and any rust are dealt with first, and acrylic needs a primer over metal. The chemistry is then chosen against how the roof drains and how it is used.

Can I re-coat a silicone roof with acrylic?

Not as a default. Silicone is difficult to prime over, so acrylic over silicone needs specific manufacturer approval, adhesion testing and the correct primer. The reliable re-coat path on a silicone roof is silicone.

When should a commercial coating be re-coated?

Before the film fails, not after. The film thickness is measured periodically and the re-coat is scheduled against the specification the manufacturer warranty rides on, rather than a calendar interval.

Does an elastomeric coating need a permit in LaPlace?

Nothing the parish publishes says a coating does or does not need a permit. The Permit Division answers that for a specific scope, and where a coating sits in the code is set out on our commercial roof coating page.

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Commercial Elastomeric Coatings in LaPlace, LA

Big Easy Roofing specifies elastomeric coatings across LaPlace and the east bank of St. John the Baptist Parish. A coating has to bond to the roof that is already there, so the substrate narrows the choice before ponding water, sun and foot traffic rank what is left.

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Service

City

Substrate firstThen the failure modes

Six roof typesOn the parish Assessor page

Table 1509.2A standard per chemistry

Re-coat compatibilityNarrows with silicone

LaPlace commercial elastomeric coatings at a glance

An elastomeric coating is a flexible film that has to bond to the roof already there. Three chemistries dominate commercial work, and the building code text lists a material standard for acrylic (ASTM D6083), silicone (D6694) and moisture-cured polyurethane (D6947). The substrate is the first filter.

The parish form asks the roof type

Assessor's Office page

The parish Commercial Permit Application carries a page for the Assessor's Office. Its roof line reads "Type of Roof (circle one): Composite Galvanize Painted Metal Aluminum Shingle Slate".

Half the list is metal

Galvanize, Painted Metal, Aluminum

Our reading, not the parish's: three of the six choices are metal, and metal is one of the substrates coatings are proposed for. The list names no single ply membrane, no built up roof and no coating.

A standard in the code table

IBC Table 1509.2

Section 1509.2 says roof coating materials shall comply with the standards in Table 1509.2. The table lists ASTM D6083 for acrylic coating, ASTM D6694 for silicone coating and ASTM D6947 for moisture-cured polyurethane coating.

Failure mode one

Ponding water

Silicone cures by moisture and tolerates standing water once cured. Acrylic coatings are water dispersed and rehydrate under ponding, so an acrylic film under standing water softens. Where ponding is present, silicone is normally the shortlist.

Failure modes two and three

Sun and foot traffic

Weathering, dirt pickup and reflectance retention vary by chemistry and by product, and polyurethane systems are commonly specified where abrasion resistance leads, including traffic surfaces on spray polyurethane foam.

The trap

Re-coat compatibility

Silicone's low surface energy is difficult to prime over, so silicone over silicone is the reliable re-coat path. Choosing silicone today usually decides the chemistry family of every future re-coat.

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 parish form on this page is the Commercial Permit Application revised 6/13/25, as St. John the Baptist Parish published it when we read it in September 2026. The code table is from the model International Building Code Chapter 15 text we read the same month. Elastomeric coatings are priced on substrate condition, chemistry and specified dry film rather than a published range, so call Big Easy Roofing for a scoped price.

The three chemistries against the three failure modes

Once the substrate has filtered the shortlist, three failure modes rank what is left: ponding water, sun and dirt pickup, and foot traffic. A chemistry that is a poor fit for the leading failure mode on the roof will underperform whatever the datasheet says, so the survey ranks the modes first.

Chemistry	Ponding tolerance	UV and dirt pickup	Foot traffic and abrasion
Silicone	Strong. Cures by moisture and tolerates standing water once cured.	Fair. Starts reflective and can drop noticeably as dirt picks up on the low surface energy film.	Fair. Can be slippery when wet, so traffic lanes are specified separately.
Acrylic	Poor. Water dispersed, so the film rehydrates and softens under ponding water.	Good. Tends to hold its reflectance longer than silicone on a field roof, though white acrylic still discolours over time.	Poor. Softer than the other two on a traffic path.
Polyurethane	Varies by product and cure type. The product datasheet governs.	Aliphatic types hold up under UV; aromatic types need a UV stable top coat.	Commonly specified where abrasion resistance leads, including traffic surfaces on spray polyurethane foam.

The three performance columns rank the field chemistry against the leading failure modes. Traffic lanes on a silicone or acrylic field roof are often specified as the manufacturer's approved walkway system rather than a whole roof chemistry change, and re-coat compatibility follows in its own section below.

Re-coat compatibility, and why silicone narrows the future

When an elastomeric coating reaches the end of its film life, the next coat has to bond to what is left of the first one. Re-coat compatibility is a chemistry question decided by the coating going on today, and adhesion is always confirmed with the manufacturer of the incoming system.

Silicone

Re-coat usually stays silicone

Low surface energy makes silicone hold up under ponding water and also makes it difficult to prime over. Silicone over silicone with the correct preparation is the standard re-coat path. Other chemistries over silicone need specific manufacturer approval and adhesion testing.

Acrylic

Wider re-coat compatibility

A sound acrylic film usually accepts silicone, polyurethane or another acrylic on re-coat, subject to product specific adhesion checks, primer requirements and the correct cleaning. The trade off is on the ponding and traffic columns.

Polyurethane

Wider re-coat compatibility

Polyurethane usually accepts most re-coats with the correct primer. Aromatic polyurethane is normally top coated with a UV stable finish within a defined window, because the base itself is not UV stable.

The code position

On another page

Where a coating sits in the building code's reroofing section is set out on our commercial roof coating page. The compatibility question here is a chemistry decision rather than a code one.

Where a chemistry choice comes back to cost you

A silicone roof that has reached the end of its film life presents two options, and both are chemistry decided. Silicone over silicone with the correct wash is the standard answer. A full removal to bare substrate is possible and expensive, and it is the route back to acrylic or polyurethane over that roof.

So the silicone choice today is usually a commitment to silicone for the life of the roof. On a low slope roof that ponds, that is normally the right commitment, and it is worth being direct about at the specification stage.

How the survey ranks the failure modes

Every roof gets three questions: where water stands after rain, how much traffic the roof sees, and how much sun the unshaded field takes. The answers rank the failure modes on that roof before a manufacturer or a price is named.

Where ponding leads, silicone often tops the shortlist. On a metal building that drains fully, the ranking often runs sun first and traffic second, and acrylic on the field with an approved walkway system on the access lanes can be the better answer.

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The parish roof types and the substrate question

The parish Commercial Permit Application carries a page for the Assessor's Office, and its roof line offers six choices: Composite, Galvanize, Painted Metal, Aluminum, Shingle and Slate. Our reading, not the parish's: on a coating job the question that list raises is the substrate, because the film has to bond to it.

What the Assessor page says

Under its heading, the page reads: "By order of the Regular Session of the Louisiana Legislature, R.S. 47:1957(B) was amended by Act 829, St. John the Baptist Parish Assessor's Office is now required to have the following information on all commercial construction located in the parish". Its roof line reads "Type of Roof (circle one): Composite Galvanize Painted Metal Aluminum Shingle Slate".

The form's as needed list includes "Completed Information For Assessor's Office Form (required for renovations only)." The form is on the parish Building Permits page.

What the list does not tell you

The form does not say whether a coating job needs this page, and it does not say which box a coated roof belongs in. It does not define Composite either. We do not guess at any of the three.

Our practice, not a parish rule: where a coating scope goes to the Permit Division, we ask on (985) 651-5565 which pages of the form it wants and how the roof should be described.

Why the substrate comes first

Not every chemistry adheres to every substrate. Silicone bonds to most existing coatings including its own with the correct wash; acrylic needs a sound, clean substrate and a primer over metal; polyurethane is standard on spray polyurethane foam and needs the correct primer over most single ply membranes.

On galvanized, painted or aluminum metal, fastener condition, laps and any rust decide the preparation before a chemistry is named. The substrate filters the shortlist, then the failure modes rank what remains.

Big Easy Roofing Process

The chemistry is chosen against the substrate and then the failure modes on the specific roof. Four steps, and the shortlist is drawn in step two.

Roofer checking laps, fasteners and ponding zones on a LaPlace commercial metal roof before specifying a coating

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Survey the substrate and the failure modes

The existing covering or metal is identified and its condition recorded: seams, laps, fasteners, rust and any old coating. Ponding zones and traffic lanes are mapped, after rain where possible.

Draw the shortlist

The substrate filters the chemistries first. The leading failure mode then ranks what is left: ponding usually shortlists silicone, sun on a draining roof often acrylic, and heavy traffic polyurethane.

Written specification and price

The scope names the chemistry and its material standard, the specified dry film, the preparation and primer, and any walkway system. Re-coat compatibility is noted on the file.

Apply, measure, hand over the paperwork

Wet film readings taken as the coating goes on, the finished dry film documented, and the coating manufacturer warranty handed over with a note of the chemistry for the next re-coat.

Everything else we do in LaPlace

The rest of the Big Easy Roofing services available in LaPlace, each with its own page and scope of work. The code position of a coating sits on the commercial roof coating page, and the moisture survey behind any coating check is on the commercial inspections page.

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