GacoFlex S42 Silicone Roof Coating System Guide

How GacoFlex S42 fits into a complete commercial roof restoration scope from adhesion testing and repairs through coating application and closeout.

Roofing Contractors Association of Texas member

Commercial roofing guide 02/17/2026

Planning a GacoFlex S42 restoration project

GacoFlex S42 is a 100% silicone roof coating intended to renew eligible weathered roofs with a seamless protective surface. Gaco describes it as a high-adhesion coating that can be used over multiple roof substrates and withstand permanent ponding water, subject to current specifications and an adhesion test.

This guide focuses on the system decisions that belong ahead of product application: roof condition, moisture, preparation, repairs, primers, detailed areas, coverage, cure, and inspection.

Decision guide

What Gaco publishes for S42

Gaco describes S42 as a single-component, high-solids silicone coating for renewing weathered roofs. Published benefits include adhesion to multiple substrates, ponding-water resistance, UV protection, and specified system-warranty routes. The manufacturer states that an adhesion test should always be performed.

Project decisions should use the current product data, substrate specification, details, and written requirements for the selected assembly.

Manufacturer reference: GacoFlex S42 product and technical resources.

Decision guide

The roof must qualify for restoration

Confirm roof material, age, previous coating, drainage, moisture, adhesion, contamination, surfacing, seams, laps, fasteners, penetrations, flashings, perimeters, repairs, and structural or deck concerns. Investigation should distinguish isolated defects from conditions that require wider removal or replacement.

Ponding-water resistance does not remove the need to understand drainage, correct failed components, and address wet or unsound materials.

Decision guide

Components of an S42 project scope

Condition review and adhesion testing

Confirm the substrate, moisture, defects, previous materials, preparation route, and bond performance.

Cleaning, repairs, and primers

Prepare the surface and complete the specified substrate treatment before finish coating.

Seams, penetrations, and flashings

Use compatible repair and detail materials at vulnerable roof interfaces and transitions.

S42 silicone application

Apply and verify the specified coverage across field areas and completed details within suitable weather limits.

Decision guide

Adhesion testing informs the specification

An adhesion test should represent the cleaned, prepared roof and any proposed primer. Multiple roof areas or previous materials may require more than one test location. Results should be recorded and used to confirm or revise the system route.

Testing does not replace investigation of concealed moisture, loose layers, deteriorated insulation, deck concerns, or failed drainage.

Decision guide

Repairs and detailed areas come first

Fasteners, metal laps, membrane seams, penetrations, curbs, walls, drains, scuppers, gutters, terminations, and perimeters should be repaired and detailed before field coating. The scope should identify reinforcement, sealants, patch materials, and inspection points for each condition.

Coating thickness at peaks, transitions, and irregular surfaces requires particular attention during application.

Decision guide

Application controls and daily records

Monitor surface dryness, temperature, humidity, rain risk, wind, material storage, mixing where required, coverage, and cure. Daily quantities and completed areas should be reconciled with the specified rate.

Photographs, weather logs, adhesion results, detail inspections, material-use records, and punch-list completion strengthen the closeout package.

Decision guide

Compare S42 with other project routes

S42 may be compared with other silicone systems, acrylic coating, recover, or replacement. The comparison should account for retained materials, moisture, repair extent, details, drainage, compatibility, disruption, access, maintenance, inspection, and written product requirements.

A lower initial scope is not automatically the responsible choice if the roof cannot provide a reliable base.

Decision guide

Inspection and compatible maintenance

Inspect drainage, detailed areas, rooftop equipment interfaces, traffic zones, repaired locations, and any new penetrations. Clean localized areas before compatible repair and record changes against the roof plan.

Future recoating should begin with a new condition review and adhesion verification.

Frequently asked questions

GacoFlex S42 Silicone Roof Coating Systems FAQs

Can any commercial roof be coated?

No. The surface must be compatible and sound, with moisture and existing defects addressed before the proposed coating is applied.

Will coating repair holes or loose panels?

No. Damaged metal, failed connections and other defects need their own repairs before coating.

Can a new coating go over an old coating?

Only where the old finish is suitable to remain. Adhesion, contamination and compatibility checks help establish the preparation required.

Is silicone always better than acrylic?

No. Product choice depends on the substrate, exposure, application conditions and future maintenance. Compare the specified system for your roof.

Does ponding-water resistance mean drainage can be ignored?

No. A coating does not increase drain capacity or correct the roof's fall. Persistent standing water still needs investigation.

Why do two coating quotes differ so much?

Preparation, repairs, primer, detail reinforcement and finished thickness can vary substantially. Compare those items as well as roof area.

Can the coating be applied in any weather?

No. Roof temperature, surface moisture, rain and curing conditions must fall within the selected product's limits.

Will a reflective coating reduce our energy bills?

It may reduce solar heat absorbed by the roof. Actual building savings depend on insulation, climate, HVAC use and other conditions.

Is an extra 10 or 20 years guaranteed?

No general lifespan promise applies to every roof. Review the actual proposed work and the terms of any applicable written warranty.

What information is useful before a coating survey?

The address, known roof material, existing coating name and current defects. Old product records and photographs help if available.

Move from guidance to property information

Discuss the commercial roofing decision for your facility

Share the property address, known roof information, current concern, and available project documents so the next step can be defined around the building.

Discuss Your Project

UK refurbishment experience, a Texas office

Refurbishment specialists

Our business grew through roof and cladding refurbishment in the UK. That experience shapes the work we now offer from our Texas office.

Repair what can be retained

We investigate the roof problem and explain what can be repaired, restored or replaced, so you can decide how to invest in the building.

Roofing and cladding together

We can coordinate roof, insulation, wall panel and drainage work, including the connections where separate repairs can leave problems behind.

A plan for your working building

We agree access, work areas and protection with your site team, including any restrictions needed while the roof is opened.