Fosroc Dekguard W (Dekguard A Plus)
Water-based acrylic anti-carbonation and waterproof protective coating for exposed concrete, RCC facades and masonry, conforming to BS EN 1504-2.
What is it?
A single-component, water-based acrylic copolymer protective coating (formerly branded Dekguard W, now catalogued by Fosroc as Dekguard A Plus) that seals concrete and masonry against carbon dioxide, chloride ions and rain while staying vapour-permeable.
Where is it used?
Atmospherically exposed RCC facades, bridge parapets and abutments, precast cladding, boundary and retaining walls, and masonry in coastal or polluted urban settings.
Why use it?
It slows carbonation and chloride-driven reinforcement corrosion, keeps liquid water out, and still lets the substrate breathe, extending service life without trapping moisture.
How is it applied?
Prepare and prime the surface with Dekguard Primer, then apply two topcoats by brush, roller or airless spray at roughly 5.5 sq.m per litre per coat to build a dry film of at least 150 microns.
About Fosroc Dekguard W (Dekguard A Plus)
Dekguard W is Fosroc’s water-based acrylic protective coating for concrete and masonry that face the weather day in and day out. If you have specified or sourced it under the name Dekguard W, note that Fosroc has since renamed the same product Dekguard A Plus; the chemistry, the BS EN 1504-2 conformance and the field behaviour are unchanged, so existing specifications remain valid. On an Indian project it earns its place on exposed RCC facades, bridge elements, precast panels and rendered walls, where the twin threats are atmospheric carbon dioxide and, near the coast or in industrial belts, airborne chlorides. Both attack the passive layer around the reinforcement and set corrosion in motion long before spalling becomes visible.
What makes this grade practical for site teams is that it is single-component and water-based. There is no mixing ratio to get wrong, no solvent odour to manage in occupied or enclosed areas, and clean-up is with water. It arrives ready for use, tinted or in standard shades, and goes down with ordinary brushes, rollers or airless spray. Because it is decorative as well as protective, one system handles both the durability specification and the finished appearance of the elevation, which removes a separate paint trade from the programme and keeps the warranty under one manufacturer.
The technical insight
The protection works on a simple but deliberate imbalance in permeability. Concrete carbonates when atmospheric CO2 diffuses into the cover, reacts with the alkaline pore solution and drops the pH until the steel loses its passive protection. Dekguard W lays down a continuous acrylic film that is a heavy barrier to that gas: tested to BS EN 1062-6 it gives a CO2 diffusion resistance equivalent to roughly 95 metres of still air, so the carbonation front effectively stalls at the surface. The same film is an equally tough barrier to chloride ions, oxygen and liquid water, which is why it suits marine and de-icing exposure. The clever part is that while it stops those aggressors, it stays open to water vapour, with a vapour-diffusion Sd of about 0.7 metres (BS EN ISO 7783-2). Moisture already inside the slab can escape rather than build up behind the coating, so you avoid the osmotic blistering and delamination that defeat non-breathable paints on damp substrates. Backed by a bond strength around 2.8 MPa to EN 1542 and a Euroclass B-s1,d0 fire rating, the film stays adhered and reaction-to-fire compliant over the long term.
Where it is used
- Anti-carbonation protection of atmospherically exposed reinforced concrete facades and columns
- Bridge parapets, fascias, abutments and other exposed structural concrete
- Precast and in-situ concrete cladding panels needing a durable decorative finish
- Concrete boundary walls, retaining walls and water-tank exteriors
- Rendered and fair-faced masonry on external elevations
- Coastal and marine structures exposed to airborne chlorides and salt spray
- Structures in polluted or industrial urban environments with high CO2 loading
- Protective topcoat over Renderoc concrete repair and reinstatement systems
Key advantages
- Single-component and water-based, so no site mixing, low odour and water clean-up
- Strong barrier to carbon dioxide (about 95 m CO2 resistance to BS EN 1062-6) that arrests carbonation
- Also resists chloride ions, oxygen and rain, suiting coastal and industrial exposure
- Vapour-permeable (Sd about 0.7 m) so trapped moisture escapes and blistering is avoided
- Conforms to BS EN 1504-2 for surface protection of concrete
- Decorative and protective in one system, available in a wide colour range
- Applies by brush, roller or airless spray, easing large-facade productivity
- Good long-term weathering and UV performance across Indian climates
Limitations & considerations
- Water-based film, so it needs dry weather and cannot be applied if rain is likely within about 2 hours at 20C (longer when cooler)
- Do not apply below 5C substrate temperature, within 3C of the dew point, or above 85% relative humidity
- Requires priming with Dekguard Primer at roughly 0.4 litre per sq.m for a sound bond
- Blowholes, pitting and rough substrates must first be filled and levelled with a Renderoc mortar or fairing coat
- As a rigid acrylic it is not crack-bridging; for structures with active dynamic cracks an elastomeric grade such as Dekguard Elastic or E2000 is more appropriate
- Custom-tinted batches are typically made to order and non-returnable, so confirm shades before ordering
Selection & best practice
Success with Dekguard W is decided before the topcoat opens. Start with a clean, sound, laitance-free substrate; fill blowholes and pitting with Renderoc FC and level rough areas with a Renderoc fairing coat so the film has an even base to bridge. Prime with Dekguard Primer, applying enough coats to reach about 0.4 litre per sq.m. Apply two topcoats at roughly 5.5 sq.m per litre per coat, targeting a wet film near 180 microns each so the finished dry film is at least 150 microns; porous or textured surfaces drink more material and may need an extra pass. Allow about 6 to 8 hours between coats at 20C, longer in cooler or humid conditions. Check the weather window first: substrate above 5C and at least 3C above dew point, humidity below 85%, and no rain expected within a couple of hours of application. Keep a wet edge, work in manageable bays on large elevations, and record actual consumption against the theoretical rate to catch under-application early.
Specifications
| Product type | Single-component water-based acrylic copolymer protective and anti-carbonation coating |
| Standard | Conforms to BS EN 1504-2 (principles 1.3, 2.2, 8.2) |
| Coverage | Approx. 5.5 sq.m per litre per coat (substrate-dependent) |
| Dry film thickness | Minimum 150 microns over two coats |
| Wet film thickness | Approx. 180 microns per coat |
| CO2 diffusion resistance | Approx. 95 m equivalent air (BS EN 1062-6) |
| Water vapour permeability | Sd approx. 0.7 m (BS EN ISO 7783-2), vapour-permeable |
| Bond strength | Approx. 2.8 MPa (EN 1542) |
| Drying / overcoat time | Approx. 6 to 8 hours at 20C between coats |
| Pack size | 10 litre packs |
Industry use cases
Infrastructure and bridges
Protects parapets, piers and abutments from carbonation and de-icing or coastal chlorides, extending the life of exposed structural concrete.
Commercial and residential facades
Delivers a durable decorative anti-carbonation finish on high-rise RCC elevations and precast cladding in one manufacturer-backed system.
Coastal and marine structures
Its chloride and water resistance suits jetties, sea walls and buildings in salt-laden coastal air where reinforcement corrosion is aggressive.
Concrete repair and rehabilitation
Used as the finishing topcoat over Renderoc repairs so patched and parent concrete share one protective, uniform coating.
Industrial and urban environments
Guards facades and boundary walls in high-pollution belts where elevated atmospheric CO2 accelerates the carbonation front.
Frequently asked questions
Is Dekguard W the same as Dekguard A Plus?
How much Dekguard W do I need per square metre?
Does it stop reinforcement corrosion?
Do I need a primer, or can I coat bare concrete directly?
Can it be applied during the monsoon?
Will it crack if the concrete moves?
How we position Fosroc Dekguard W (Dekguard A Plus)
Within the Fosroc Dekguard family, Dekguard W (Dekguard A Plus) is the water-based, low-odour choice ideal for enclosed areas and projects that want water clean-up. Where a premium solvent-based aliphatic acrylic is preferred for maximum gloss and colour retention, step up to Dekguard S; where the substrate has active movement or dynamic cracks, specify the elastomeric, crack-bridging Dekguard Elastic or Dekguard E2000. Pair any of these with Dekguard Primer for adhesion and with Renderoc FC or Renderoc fairing coats for surface reinstatement before coating. Space Arc also stocks comparable protective and anti-carbonation systems from other brands we distribute, including MasterProtect from Master Builders Solutions and Zincseal or protective coatings from STP, so consultants can match the coating to the specification and budget on hand.
Related Protective Coatings products
Source Fosroc Dekguard W (Dekguard A Plus) for your project
Authorised distribution, technical advice & professional application across Delhi NCR and Pan-India.