Sydney Based + National Delivery
Sydney Based + National Delivery
Silonexx is a solvent-borne DPC injection fluid, classified as a chemical damp-proof course system for pressure injection into existing masonry.
Proprietary chemistry. Moisture-activated cure. For professional and trade installation.
Standard clay brick (dense, pre-1960s)
Primary application substrate for Silonexx. Drill horizontally into the mortar bed joint at the DPC height. Lime mortar joints assist product distribution through the wall. Dense clay brick accepts the product well and provides reliable CSZ confirmation at adjacent holes.
Sand stock brick
Suitable. Higher absorption rate than dense clay. Monitor adjacent holes closely as product movement is faster. Increase product volume allowance accordingly.
Extruded brick (cored/hollow)
Extruded bricks are brittle and must not be drilled through the face. Drill into the mortar joint immediately above the target brick row. Fill the exposed extrusions with injection fluid, the product distributes through the cores. When the injection nozzle is removed from a drilled brick face, product drains out through the extrusion holes. Mortar joint drilling above the brick row avoids this and maintains product in the wall.
Concrete masonry unit (Besser block / CMU)
Drill into the mortar joints at the vertical supports, at the ends or centre dividers of the block, not into the hollow cells. The product distributes through the mortar and solid concrete sections. Hollow cells do not accept or distribute the product.
Hebel (autoclaved aerated concrete)
Does not inject well. Hebel’s cellular structure does not support the capillary distribution mechanism required for CSZ establishment. Not recommended. Contact Silonexx technical before specifying.
Sandstone
Sandstone block itself is dense and largely impermeable to injection fluid, product will not penetrate the face of the stone. Technique: inject into the mortar joints both vertically and horizontally, surrounding the sandstone blocks at the DPC height. Product must be confirmed exiting the opposite side of each mortar joint to verify full penetration. Sandstone walls in Australian heritage construction are typically 400mm deep. Product volume calculation: measure wall thickness (m) × wall length (m) = m² of DPC zone. Apply 12 litres per m². For complex or deep sandstone work, contact Silonexx technical for site-specific advice.
Limestone
Not recommended. Limestone is typically too dense to accept the product and does not provide the pore network required for distribution or bonding. Assess individually and contact Silonexx technical.
Rubble fill / loose-laid construction
Suitable with assessment. Loose-laid rubble walls with mud or lime mortar require thorough saturation of the entire DPC row due to the irregular and discontinuous pore structure. The injection sequence must cover the full length and depth of the wall without gaps. Important: rubble walls that are fully saturated with water are not suitable for treatment. Silonexx operates on residual moisture in the substrate, not standing water. Saturated walls should be allowed to dry to a manageable moisture level before treatment. Walls genuinely wet from rising damp are rarely saturated in the interior — rising damp produces dampness, not wetness. Surface wet conditions are typically salt-related and superficial.
Cavity wall
Treated routinely. Where both skins are accessible, treat each independently. Where only one skin is accessible, single-skin injection is effective for that wythe, the two skins of a cavity wall are not physically connected and function independently for DPC purposes. If the cavity is not bridged, and the internal skin only is affected, the internal skin alone can be treated. To inject through a full cavity wall from one side, use a drill bit long enough to bridge the cavity and reach the required depth in the far wythe.
Infill slab / DPC in incorrect position
Where a concrete infill slab bridges an existing DPC or the DPC is positioned above floor level, inject the closest brick course immediately above the concrete slab. This establishes a new chemical DPC below the bridge point. Full site assessment is required to confirm the correct injection height relative to ground level, slab level, and any external fill or soil.
The Tri-Phase Molecular System™ operates through three sequential stages.
Phase 1
Capillary penetration. The low-viscosity fluid distributes through the masonry pore network under pump injection pressure, reaching full wall depth and lateral spread.
Phase 2
Moisture-activated bonding. On contact with residual moisture in the pore walls, the silane chemistry activates: hydrolysis occurs, the active compound condenses onto pore surfaces and bonds covalently to the mineral silica in the substrate.
Phase 3
Permanent mineral integration. The treated zone becomes permanently hydrophobic at the mineral level. The pore structure is not blocked. The masonry retains vapour permeability.
| Parameter | Value | Notes |
|---|---|---|
| Drill diameter | 10mm | Standard for all substrates |
| Drill depth | Half brick depth | For cavity walls injected from one side, extend to full depth of the far wythe |
| Hole position | 60mm in from each brick edge | Vertical centre of mortar joint. Extruded brick: drill mortar joint above target row, not the brick face |
| Injection height | Site assessed | Dependent on floor level, ground height, DPC position and substrate configuration |
| Injection pressure | ~50 PSI | Set at pump. Standard for all substrates |
| Product volume — standard brick | 300mL per brick | Approximately 20L per 10 linear metres single skin. 20L per 5 linear metres double brick |
| Product volume — sandstone | 12L per m² | Wall thickness (m) × wall length (m) × 12 = total litres |
| Treatment completion criterion | Capillary Saturation Zone™ | Product must confirm at all adjacent holes before the injection sequence is closed |
Following injection, the carrier solvent evaporates from the treated zone over a period of days, depending on ambient temperature, ventilation, and initial substrate moisture content. Rendering is typically undertaken five to seven days after injection is complete to allow sufficient solvent evaporation before the render is applied.
Render specification:
Use a salt retarder with a 3:1 sand and cement render. No other additives. Do not use acrylic render over a wall that has had rising damp. The plasticisers and polymers in acrylic render can draw residual salts from the substrate to the surface, causing a recurrence of salt damage and moisture-related issues even where the DPC treatment is performing correctly.
Once the solvent has evaporated, the silane chemistry activates on contact with moisture, either from residual moisture in the substrate or from atmospheric humidity. If the substrate is dry at the time of solvent evaporation, activation may be deferred until moisture becomes available. The bond, once formed, is permanent.
Wall drying after treatment: approximately 25mm per month under normal Australian ambient conditions. Walls with elevated salt loads or high initial moisture content may dry more slowly.
Note for applicators and clients:
Following injection and rendering, a rain event prior to painting may cause silane to migrate to the render surface, producing a sheen or discolouration that looks wet. In most cases the render surface is not actually wet. A moisture meter will not show elevated readings, and a tissue pressed against the surface will remain dry. This is the silane activating at the render face and is not evidence of treatment failure or water ingress. The effect resolves once the render is sealed with paint.
This should be distinguished from genuine surface wetness. Where acrylic render has been applied over a substrate with elevated salt content, the render can draw salts to the surface and produce actual wetness. If a tissue test or moisture meter confirms genuine moisture, assess the render system and substrate salt load rather than the DPC treatment.