Repair Systems — Rising Damp
Breathable render systems
Technical product reference for breathable external render systems on masonry walls affected by rising damp — mineral, silicate and lime renders that allow moisture vapour to escape during the wall drying-out period after DPC injection treatment.
What are breathable render systems for rising damp remediation?
Breathable render systems are vapour-permeable external render products used on the external face of masonry walls undergoing or following rising damp treatment. The defining property is vapour permeability — the render must allow moisture vapour to escape from the masonry substrate as the wall dries out after DPC injection treatment, rather than trapping it beneath an impermeable film.
Mineral renders (cement-based), lime renders and silicate renders are all vapour-permeable. Acrylic renders and polymer-modified renders typically have significantly lower vapour permeability and are not appropriate for use on walls still drying after rising damp treatment. Applying an acrylic render to a rising damp wall traps moisture, accelerates salt crystallisation damage at the render surface, and causes premature render failure.
For external rising damp walls, the treatment sequence is: DPC injection → old external render stripped → wall begins to dry → breathable mineral or lime render applied to external face → WTA renovation plaster applied to internal face. The breathable external render system allows the wall to continue drying through both faces during the post-treatment drying period.
Do not confuse with:
- WTA renovation plasters (Remmers SP, Mape-Antique) — internal plasters for rising damp walls — different product category — see the salt-resistant plaster page
- Acrylic or polymer-modified renders — not breathable — not appropriate for rising damp walls — will trap moisture and fail
- Crystalline waterproofing slurries (Xypex, Vandex Super) — positive-side active waterproofing — not a breathable render for rising damp
- Breathable masonry paint (Keim Granital, silicate paint) — a topcoat coating — not a render system — see the breathable paint page
- Textured acrylic topcoat coatings — acrylic-based — not vapour permeable — not suitable over rising damp walls
Product Reference
Individual products — one card each — scroll to view all
Parex Australia
Parex Monorex GM / GF (through-coloured render)
One-coat through-coloured breathable mineral render
Parex Monorex is a through-coloured, one-coat, semi-lightweight, weather-resistant and breathable decorative mineral render for masonry and concrete — a hydraulic mortar of cement, lime, siliceous / calcareous sands, mineral pigments and admixtures. EN 998-1 with BBA Certificate 21/5888; 48 colours; 25 kg bags, 12-month shelf life; machine (10–12 bar water / 15–16 bar pump) or manual application. NOTE: the page name 'Monorex GT' was not located — the current Monorex renders are GM (medium grain) and GF (fine grain). Confirm the correct AU product and the vapour-permeability value with Parex / Sika Australia.
Keim Australia
Keim Universalputz (mineral render)
Mineral lime-cement render — silicate coating system
Keim Universalputz is a mineral renovation / thin-layer exterior render based on lime-cement with organic additives and fibre reinforcement, forming a coordinated render / coating system with Keim potassium-silicate coatings. Mineral renders are highly vapour-permeable, suited to heritage and damp masonry that must keep drying. Confirm the current AU Keim render product, the exact vapour-permeability value and pack sizes with Keim Australia.
Remmers Australia
NHL Lime-Based Breathable Render — CONFIRM Remmers product
Natural hydraulic lime (NHL) breathable render
Natural hydraulic lime (NHL) renders are highly vapour-permeable, multi-coat lime renders suited to soft / heritage masonry and lime mortars, used on the external face after rising-damp treatment to keep the wall drying. NHL breathability varies with grade (NHL 2 most breathable, NHL 5 least). NOTE: the page name 'Remmers Kalkputz' could not be confirmed and 'NHL-Kalkputz' is a KEIM product — confirm the correct current AU NHL lime render, grade and coat build with the manufacturer.
System Comparison
Breathable render systems — confirm all selections against the current manufacturer TDS before specifying.
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Disclaimer
Information is general only. Product selection must be confirmed against project requirements, substrate type and condition, manufacturer technical data sheets, and applicable standards. Confirm vapour permeability of selected render is appropriate for the application stage. Do not rely on this reference as a substitute for professional advice.