What actually separates them — and the one number that decides your warranty.
Most coating quotes name a chemistry and a warranty length — “silicone, 20-year” — and stop there. That leaves out the number that actually determines whether you get a 20-year warranty at all: how much coating goes on the roof.
This guide compares silicone and acrylic on the things that are written down in manufacturer specifications, not the things that get repeated in sales conversations.
A coating warranty is not a promise a contractor makes. It is a manufacturer specification, and the coverage term is tied to a published application rate — gallons per square — and the resulting dry film thickness in mils.
Here is GAF’s own published ladder for three of its coating assemblies. Read across: the same product buys a longer term only when more of it goes on.
| Assembly | 10-year | 15-year | 20-year |
|---|---|---|---|
| Unisil silicone over metal | 2.00 gal/sq 23 mils | 2.75 gal/sq 31 mils | 3.50 gal/sq 40 mils, 3 coats |
| Unisil HS silicone over smooth asphaltic | 1.75 gal/sq 27 mils | 2.25 gal/sq 35 mils | 2.50 gal/sq 39 mils |
| Premium Acrylic HydroStop fabric reinforced, over smooth asphaltic | 4.00 gal/sq 40 mils | 4.50 gal/sq 44 mils | 5.50 gal/sq 52 mils |
| Acrylic over smooth asphaltic | 3.00 gal/sq 25 mils | 4.50 gal/sq 37–42 mils | not offered |
Two things fall out of that table immediately.
First, “20-year coating” is a thickness, not a product. Unisil over metal is the same coating at 10, 15 and 20 years. What changes is that the 20-year term requires 3.50 gallons per square across three coats instead of 2.00 across fewer. A quote priced at the 10-year rate does not become a 20-year warranty because the proposal says 20 years on it. This is checkable: ask which application rate your price is based on, and compare it to the row above.
Second, plain acrylic has a ceiling. GAF’s acrylic-over-smooth-asphaltic specification has no 20-year row at all. If you want a 20-year term on an acrylic system, it has to be the fabric-reinforced HydroStop assembly — which is a different, heavier build at 5.50 gallons per square.
This is the clearest practical divider. Acrylic product data sheets restrict the material from surfaces prone to ponding water. That is a manufacturer restriction on the product, and it is the reason acrylic comes off the table on roofs that hold water after rain.
What we will not tell you is that silicone is immune to ponding. Manufacturer warranty documents routinely exclude damage arising from inadequate drainage regardless of chemistry, and a coating does not change how a roof drains. If your roof ponds, the real conversation is about drainage, not about which bucket to open.
Both are reflective and manufacturers publish a solar reflectance value for each product, measured to ASTM C1549. We quote the figure from the data sheet of the product we are actually installing rather than a generic percentage, because what a reflective roof saves you depends on your insulation, HVAC and how the building is used.
Silicone is generally recoated with silicone — once a roof is siliconed, that is the path it stays on. It is worth knowing at the outset, because it shapes what the next restoration cycle looks like rather than being a defect.
This is the part that costs building owners money, because all three can be described as “a 20-year GAF warranty.”
| Level | What it covers | Who can issue it |
|---|---|---|
| Material only | Manufacturing defects in the coating. Explicitly excludes improper workmanship in applying the products, and liability is capped at the cost of the coating. Not transferable. | Anyone |
| Emerald Pledge system warranty | The GAF system, up to 20 years, including labor to correct a covered leak. Liability capped at the original installed cost. Transferable once, for a fee. | GAF CoatingsPRO or CoatingsPRO+ contractors |
| Diamond Pledge NDL no dollar limit | “Edge to edge” repair of leaks through the coating from a manufacturing defect, ordinary wear and tear, or workmanship in applying the materials. No dollar limit on covered repairs. Up to 20 years, transferable for a fee. | GAF CoatingsPRO+ contractors only |
The gap that matters is workmanship. A material-only warranty covers the bucket, not the installation — and most coating failures are installation failures, not manufacturing defects. Only the NDL guarantee covers workmanship in applying the materials, and GAF restricts who can issue it.
Note also that plain acrylic over smooth asphaltic is marked ineligible for the NDL guarantee at any coverage term. If the NDL guarantee is what you want, that narrows the system before anything else does.
We install GAF liquid-applied coating systems, and RISE Roofing is a GAF CoatingsPRO+ contractor — the level GAF requires before a contractor can issue the Diamond Pledge NDL roof guarantee. That is why we can put a no-dollar-limit guarantee on a coating job rather than a material-only certificate.
What that means in practice when you get a quote from us: we tell you the system, the application rate, the resulting dry film thickness, the coverage term those add up to, and which warranty level you are getting. If a competing quote will not give you those five things, they are not describing the same product.
On top of the manufacturer’s guarantee, RISE Roofing carries its own 20-year workmanship warranty on coating installations. Those are two separate instruments covering two different things: GAF’s guarantee stands behind the system, ours stands behind the way we put it on.
A coating restores a roof that is fundamentally sound — the Roof Coatings Manufacturers Association is clear that restoration assumes a sound substrate. It is not a fix for a roof that has failed, and applying one over a wet assembly seals the moisture in permanently.
Before quoting we check for trapped moisture in the roof assembly, and manufacturer system warranties generally require that check plus adhesion testing before the warranty will be issued. Warranty documents also commonly exclude leaks caused by deterioration of the existing roof underneath the coating — which is precisely why the condition of what is already there decides whether coating is honest advice or an expensive delay.
If the substrate is saturated or the roof is past restoration, we will say so and quote the replacement instead.
Coating runs roughly $2.50–$4 per square foot against $7.50–$15 for full commercial replacement, so the economics are usually favourable when the roof is a genuine candidate. For more on the silicone system specifically, see our silicone roof coating guide, or our commercial roof coating service page.
Want to know which system your roof should get — and which warranty you would actually receive? Call RISE Roofing at (832) 224-3435 for a free inspection.
Application rates, dry film thicknesses and coverage terms are from GAF’s published liquid-applied coating Quick Spec documents and its Limited Warranty on GAF Liquid-Applied Roof Coatings. Warranty scope is from the GAF Liquid-Applied Emerald Pledge Limited Warranty and the Liquid-Applied Diamond Pledge NDL Roof Guarantee certificates. Solar reflectance is measured to ASTM C1549 and published per product. Figures apply to the specific assemblies named and are not transferable to other products or manufacturers.
Neither is better in the abstract — they have different ceilings. In GAF's published coating specifications, silicone systems reach a 20-year coverage term, while plain acrylic over smooth asphaltic tops out at 15 years and is not eligible for the Diamond Pledge NDL guarantee at any term. Acrylic manufacturers also restrict their products from surfaces prone to ponding water. Where a roof drains well and the budget matters, acrylic can be the right call; where there is ponding, or where the longest warranty is the point, silicone is.
How much coating goes on the roof. GAF's specifications set each coverage term by a gallons-per-square application rate and a dry film thickness in mils. Unisil over metal, for example, is 2.00 gallons per square at 23 mils for 10 years, 2.75 at 31 mils for 15 years, and 3.50 in three coats at 40 mils for 20 years. The warranty term is a specification, not a sales promise — ask which rate your quote is priced at.
Plain acrylic over smooth asphaltic cannot — GAF's specification for that assembly lists only 10-year and 15-year coverage terms, with no 20-year row, and marks the Diamond Pledge NDL guarantee as unavailable on both. The exception is the fabric-reinforced Premium Acrylic HydroStop assembly, which does reach a 20-year term at 5.50 gallons per square and 52 mils.
It depends entirely on which of the three warranty levels you get. A material-only warranty, which any contractor can offer, explicitly excludes improper workmanship in applying the products and caps the manufacturer's liability at the cost of the coating. GAF's Diamond Pledge NDL guarantee does cover leaks resulting from workmanship in applying the materials, with no dollar limit on covered repairs — but only a GAF CoatingsPRO+ contractor can issue it. Separately from the manufacturer's guarantee, RISE Roofing provides a 20-year workmanship warranty on its coating installations.
Acrylic product data sheets restrict their use on surfaces prone to ponding water, so ponding generally rules acrylic out. Ponding is also a drainage problem in its own right, and a coating does not fix drainage. Before we quote any coating we check the roof for trapped moisture, because coating over a wet assembly traps it permanently. If the roof holds water, the honest answer is often to fix the drainage or replace, not to coat.
We install GAF liquid-applied coating systems and we are a GAF CoatingsPRO+ contractor, which is the level GAF requires to issue its Diamond Pledge NDL roof guarantee. We specify silicone or acrylic based on your roof's drainage, substrate and the coverage term you want, and we will show you the application rate your quote is priced at. Call (832) 224-3435 for a free inspection.
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