Preparation Sequencing Guide
Substrate preparation is the most critical factor in liquid rubber system performance. This guide defines the mandatory sequence — debris removal, degreasing, mechanical preparation, moisture testing, priming and final inspection. Deviation from this sequence is the leading cause of adhesion failure and warranty rejection.
Programme Reality
Preparation typically represents 60–70% of the total programme duration on overlay projects. A 10,000m² roof requires 10–14 days of preparation before a single litre of liquid rubber is applied. Spray application itself may take only 3–5 days. The preparation is the programme.
Phase 1
Debris Removal & Initial Cleaning
Remove all loose debris, vegetation and standing water
Clear gutters and drainage outlets completely
Remove loose and blistered membrane sections
Document substrate condition with photographs
Critical Note
Do not proceed to degreasing until all debris is removed. Degreasing over debris spreads contamination.
Phase 2
Degreasing & Contaminant Removal
Identify oil, wax and silicone contamination zones
Apply compatible degreasing agent to contaminated areas
Agitate with stiff brush or mechanical scrubber
Rinse thoroughly and allow to dry
Confirm removal with wipe test
Critical Note
Silicone contamination requires specific identification and removal. Silicone acts as a bond-breaker — liquid rubber will not adhere.
Phase 3
Mechanical Preparation
Wire brush loose rust on metal substrates
Remove laitance from concrete surfaces
Feather sharp edges and protrusions
Vacuum all dust and particulate matter
Confirm surface profile is suitable for adhesion
Critical Note
Mechanical preparation alone is insufficient where active corrosion is present. Active corrosion requires chemical treatment before priming.
Phase 4
Moisture Testing & Substrate Drying
Electronic moisture meter grid survey (5m intervals)
Document all readings with location references
Identify zones above moisture threshold
Implement drying strategy (natural or active)
Retest until all readings are within threshold
Critical Note
Moisture status must be confirmed on application day — not just at survey. Rainfall between survey and application can elevate substrate moisture.
Phase 5
Primer Application
Confirm substrate is clean, dry and dust-free
Select primer compatible with substrate type
Apply primer at specified coverage rate
Allow primer to cure to touch-dry state
Apply liquid rubber within primer recoat window
Critical Note
Primer cure time varies by temperature and humidity. Do not apply liquid rubber over uncured primer. Do not exceed primer recoat window without re-priming.
Phase 6
Final Inspection Before Application
Visual inspection of full prepared area
Confirm moisture readings are within threshold
Verify primer compatibility and cure status
Document substrate condition with photographs
Sign off substrate readiness for application
Critical Note
Do not proceed to application until all preparation phases are complete and signed off. Application over incomplete preparation is the leading cause of warranty rejection.
Sequence Deviation Consequences
The preparation sequence is not optional. Each phase creates the substrate condition required for the next phase. Deviation from the sequence creates the following failure modes:
Degreasing before debris removal
Contamination spread across substrate. Degreasing agent ineffective.
Mechanical prep before degreasing
Oil and wax ground into substrate surface. Adhesion prevented.
Primer before moisture testing
Moisture trapped beneath primer. Blistering inevitable.
Application before primer cure
Primer lifted into liquid rubber. Adhesion compromised.
Application outside primer recoat window
Inter-coat adhesion failure. Membrane delaminates from primer.
Skipping final inspection
Substrate defects not identified. Application proceeds over unsound substrate.
Related Technical Reference
Inspection Checklist
Pre-specification survey requirements — visual, moisture, structural and access assessment.
Moisture Assessment Guide
Moisture meter methodology, calcium chloride testing, substrate drying requirements.
Why Preparation Failures Invalidate Warranties
Moisture, primer, contamination and warranty conditions.
Detailing Hierarchy
Penetrations, upstands, gutters, edges — the order of detailing priority.