The external final coating is applied by spraying with a pump or by hand (with a trowel) on the under-work surface that is clean and free of sticky, oily and scum materials. Excess mortar is removed from the surface and returned to the container. If needed, it is possible to apply an additional layer on top of the first layer by considering a drying period of one day.  If there are holes or a hairline crack on the surface, fill them with the external final coating and next day apply the external final coating. Moisturize the external final coated mortar with a little spray of water on the next day of applying.

Get ready to transform your construction projects with SIG’s new PRG-PRW Render Mortar, a high-performance base coat solution with upgraded adhesion, uniformity and durability. This multi-purpose base coat plaster, works perfectly for different projects from renovating rooftops and walls to completely DIYing façades and even lining a variety of surfaces. PRG-PRW is able to provide the perfect base coat plaster layer, ready for two or three subsequent lining applications. You can achieve a flawless skim coat finish at just 2–3 cm thickness using different forms of applications, helping you minimize waste and maximize quality.

Product Overview

PRG-PRW, is a plastering mortar formulated to prepare a smooth, crack-free and uniform surface with upgraded consistency. This base coat is designed to deliver an optimal substrate, ensuring that the skim coat is absolutely crack-resistant and blister-free. Compliant with EN 998-1 GP standards, our newest base coat mortar works perfectly for paints, tiles and decorative renders, making it the go-to choice for both new construction projects and renovation purposes.

Features & Technical Specifications

• High‑Performance Cement Blend: PRG-PRW is a mix of high‑grade gray or white cement, ensuring optimal strength and uniformity in every batch.
• Premium Formula: Our render mortar incorporates fine granulated lime particles for a smoother texture and a more enhanced workability.
• High-performance Additives: The upgraded formula helps PRG-PRW boost water retention and plasticity, giving the mortar a creamy consistency that’s easy to spread.
• Extended Workability Window: Despite instant adhesion on contact, the mortar remains workable for up to 30 minutes, giving you enough time for detailed finishing, even if it is your first time working with the material.
• Easy to Work With: This render mortar weighs around 1,800 g per liter when fresh, making it easy to handle and apply. This comes extra in handy for those who are trying to DIY a tiling or painting project, leaving a great first experience and neat, seamless results.
• Enhanced Strength: Our newest plastering mortar is able to achieve a comprehensive strength of over 10 N/mm² after 28 days, providing a durable and long‑lasting base coat.
• Efficient Coverage: A 30 kg bag of PRG-PRW, covers roughly around 0.6 m² at 2 cm thickness (≈50 kg/m²) of space, delivering consistent layers with virtually zero waste.
• Low Capillary Water Absorption: PRG-PRW keeps water absorption below 0.20 kg/(m²·h^0.5), protecting façades from moisture ingress even in exterior applications.
• Fire‑Reaction Rating: Our base coat contains under 1% organic content, meeting the highest non‑combustibility standards for complete safety.
• Standards Compliant: PRG-PRW fully conforms to EN 998‑1 Category GP and relevant BS EN test series for density, strength, and durability.

Benefits & Applications

1. Crack‑Resistant Base Coat: The 2–3 cm layer base coat of our product helps reduce shrinkage stresses compared to traditional 5–7 cm cement–sand screeds, resulting in a high-quality, seamless and crack-free finish.
2. Uniform Skim Coat: Even a complete beginner is able to create a smooth and blister‑free canvas for top‑coat renders or paints without any trouble.
3. Cost‑Effective & Eco‑Friendly: Our zero-waste bag design and precise mix formula helps cut down on material and disposal costs, leading to a more cost-effective and Eco-friendly outcome.
4. Versatile Usage: PRG-PRW is ideal for many different type of applications, from a plastering mortar on interior walls and exterior façades to concrete roofs and even beneath tile systems.
5. Rapid Application: The versatility in application and coverage, helps reduce labor time on large projects.

How to Use

• Surface Preparation:
  • First and foremost, make sure that the substrates (brick, block, concrete) are clean, sound, and free of dust, oils, or loose particles.
• Mixing Instructions:
  • Pour 5.5 L of clean water per 30 kg bag into a mixer.
  • Gradually add mortar while blending for 6–8 minutes until a homogenous, lump‑free consistency forms.
  • Adjust water ± 0.5 L to fine‑tune workability—less water for stronger, less shrink-prone layers.
• Application
  • Try to trowel a uniform 2–3 cm thick layer of the mortar; smooth out ridges before your initial set.
  • Cure for 24–48 hours at 20 °C / 50 % RH before proceeding with lining or skim coat.

Packaging & Storage

• Bag Sizes: PRG-PRW comes in 30 kg polypropylene bags. It is also available in 1–1.5 ton jumbo bags.
• Shelf Life: This product can maintain its performance for up to 18 months from production if kept unopened in a dry, ventilated area.
• Storage Tips: You can stack up to 8 bags high on a raised pallet. Don’t forget to protect the render mortar from ground moisture and direct sunlight.

FAQs

1. Can PRG‑PRW be applied over existing plaster?

Yes, simply ensure that the old layer is sound, cleaned, and primed before applying a new 2–3 cm base coat.

2. When can I paint or tile after the base coat?

Typically 48 hours of cure time at 20 °C and 50 % RH is enough. However, it’s a good idea to wait a little bit longer in cooler or more humid conditions.