Roof Waterproofing Coatings · an Amrize brandConcentrated cleaner for preparing roof surfaces before silicone or urethane coating — dilutes 1:9 with water, lifts dirt and oxidation so the membrane bonds to the roof, not the grime.
The jobs this product is specified for, day in day out.
Lifts oxidation and grime so the coating bonds to the roof, not to the dirt on it.
Cuts through years of atmospheric soiling before priming or coating.
Cleans sound existing membranes ahead of a recoat.
What the data sheet actually gives you on site.
One pail of concentrate makes ten — the cheapest part of any warranted coating job.
No solvent content and non-hazardous classification, so site handling stays simple.
Apply, dwell, agitate, rinse — it does the work while the crew sets up.
Coating over contamination is the fastest route to a rejected claim. This is the step that prevents it.
The facts that matter, straight from the product data.
| Type | Concentrated cleaning solution for roofing membranes and metal panels |
| Dilution | 1 part GacoWash : 9 parts clean water |
| Coverage (diluted) | General cleaning ~37 m² per 3.8 L; light soiling up to 10× further |
| Method | Low-pressure spray, 10–15 min dwell with agitation, then power-wash off and rinse until suds are gone |
| VOC / flash point | None / none — see the Safety Data Sheet for hazard classification |
| Shelf life | 5 years unopened |
| Caution | Never mix with other cleaning chemicals — avoid chlorine-based cleaners |
Type your area and we’ll do the maths — derivation shown, nothing hidden.
Everything from the manufacturer’s literature — open the part you need.
GacoWash is recommended as a surface cleaner prior to applying:
Note: GacoWash is essential for surface preparation prior to coating over aged single-ply membranes and existing coatings.
Surface Preparation
Pressure wash or clean the roof first. Combine 9 parts water with 1 part GacoWash and mix thoroughly. Pour the diluted cleaner onto the roof surface and brush it to ensure all aspects are covered. Leave to stand for 10–15 minutes. When drying out, gently douse with water to prevent full drying of the GacoWash. After 10–15 minutes, wash away using hose or pressure washer. Ensure the roof surface is completely clean and free from dirt, grime, moss and algae.
Standard Cleaning: Mix 1 part GacoWash with 9 parts clean water
Heavy Cleaning: Use higher concentrations as needed
Max Coverage: Up to 4,000 ft²/gallon at 10:1 dilution
Do not mix GacoWash with chlorine-based products or other chemicals – dangerous gas may result.
Surface Preparation
Remove debris using a broom or power broom
Inspect roof and repair cuts, loose fasteners, sealant failures before cleaning
For biological growth, treat with 1:3 bleach-water solution before power washing
Apply with low-pressure sprayer in a 3–4 ft arc pattern
Allow solution to dwell for 10–15 minutes, misting to prevent drying
Agitate heavily soiled areas with brush or broom
Use a 3,000 psi commercial power washer to rinse thoroughly
Start at the highest point and rinse down; for flat roofs, clean away from drains, then back toward them
Allow the roof to dry completely before applying primer or topcoat
Inspect for leftover debris, soap residue, and dirt—repeat cleaning if necessary
Reapplication is only needed for heavily soiled or low-drainage sections
| Dilution Ratio | Approximate Coverage |
| 1:9 (standard) | 400 ft² / gallon |
Coverage may vary based on roof material, condition, and texture.
These products are designed to work together — buying the full system is what qualifies the warranty.
Written by our technical team — free to download, no email required.
PDFFlat Roof Application GuideFelt, asphalt, torch-on, single-ply & EPDM — free 7-page guide PDFPitched Roof Application GuideMetal, cement fibre & asbestos roofs — free 7-page guide PDFGacoWash Product Data SheetOfficial Gaco PDS — dilution, method and safety dataTell us about the building and we’ll spec the job free — the right system, the right quantities, and trade rates if you’re buying for a contract.
Tell us about your building and we’ll recommend the right system — foam, waterproofing or both — surveyed, specified and quoted at no cost.
