The Complete Guide to Exterior Plastering: Techniques and Best Practices

Exterior plastering can provide not only a classic, aesthetic finish but also a weatherproof, protective layer against the elements for your home. At West & Sons Construction, as experts in exterior plastering, we like to share best practice tips, so homeowners thoroughly understand the process when we are assisting them with their exterior plastering requirements. In this guide, we’ll explore the comprehensive techniques and best practices of exterior plastering, equipping you to understand any exterior plastering task that may be required for your property.

 Understanding Exterior Plastering

Exterior plastering can also be known as stucco. Whilst there are several products on the market, typically made from cement, sand, and water. Its main function is to create a protective and visually appealing layer on external walls, serving various functional benefits, including weatherproofing and insulation. The right application not only enhances the street appeal of a property but also improves its overall durability against moisture, pests, and other environmental factors.

 Types of Exterior Plaster

 Whilst we use tried and true products, we trust that carry product guarantees, there are several types of exterior plaster on the market. Each variant comes with its unique attributes.

Traditional Stucco

Known for its flexibility and durability, it's a versatile choice for various architectural styles. Traditionally this is made from cement, sand, and water.

Acrylic Stucco

This formula is resistant to cracking and can be applied in a thinner layer, meaning this synthetic option can be more flexible than traditional stucco. It is also adaptable and can be tinted for colour.

 Lime Plaster

Lime plaster is often used in historic restoration. This material is breathable and allows moisture to escape.  It can be a more laborious application; it delivers on charm and it has a unique aesthetic appeal.

 Synthetic Finish Systems

These modern systems combine several materials, providing enhanced flexibility, insulation, and versatility in design.

 Preparing for Plastering

 Propper preparation is vital for achieving a smooth and durable plaster finish. Your Exterior Plasterer is likely to follow these steps;

 Surface Cleaning

Commencing by cleaning the surface thoroughly. Dirt, grease, or any old paint that could interfere with the plaster’s adhesion is removed.

 Assessing for Damage

Inspecting your walls for cracks, holes, or other damage that may need repair before will ensure all bases are covered before starting plastering. Appropriate fillers for larger gaps will be utilised to create a solid foundation.

 Moisture Barrier

A moisture barrier to prevent water ingress, which can weaken plaster over time should be applied at this stage.

 Mesh or Lath Installation

Installing a metal lath or wire mesh will be applied to provide a sufficient base for the plaster to adhere. We often use a three-coat mesh plaster system which delivers a strong and durable base for the plaster to cover.

Tools and Materials Needed

 Your contractor will use a plethora of expert tools for the exterior plastering process. These will include; trowels (flat and notched), hawk, mixing paddle and drill, buckets for mixing the plaster, spray nozzle for water, float for smoothing finishes, drop cloths to protect the area. As well as ample safety gear (gloves, goggles, and mask) depending on requirements.

 Application Techniques

 Once the surface has been prepared a basic guide on how your plastering contactor will tackle the plastering process is as follows;

 Mixing the Plaster

 Following the specific mixing instructions for the type of plaster being used, they will ensure the exact ratio of water to plaster. This is crucial for achieving the right consistency.

 Mixing the plaster thoroughly

A drill with a mixing paddle will be used to achieve a uniform consistency. The mixture should be thick but pourable.

 Let It Rest

Allowing the mixed plaster to rest for a few minutes before use, can help improve workability.

First Coat Application

 Wet the Surface

The wall should be lightly misted with water using a spray nozzle to ensure the surface is damp. This step helps enhance adhesion.

 Apply the Base Coat

Using a flat trowel, apply the first coat will be evenly spread across the wall, aiming for full coverage over the surface.

 Texture Tooling

If desired you are wanting a texture applied, a float can be used to create a texture on this coat. This initial layer should be left to cure for at least 24 hours.

 Second Coat Application

Apply Additional Water

Before applying the second coat, the first coat should be sprayed lightly with water to prevent it from drying too quickly.

Layering

Spreading the second layer over the first coat will be undertaken using the same method. This helps build depth and provide protection against the elements.

 Finishing Touches

Once you apply the second coat, a float or trowel will be used to achieve your desired finish. There is where you can create various textures, from smooth to rough.

 Curing and Finishing

 Curing Process

The plaster may be left to cure for up to a week to reach its full strength. This may be weather dependant and will follow from the product’s instructions. During this time, the surface can be kept damp by lightly misting it with water to prevent cracking.

 Sealing

For added protection, a sealant that helps fend off moisture, dirt, and staining may be applied.

 Painting

Once the plaster has fully cured, it will be painted using exterior-grade paint for longevity.

 Best Practices for Success

 Your contractor may advise to avoid plastering in extreme temperatures; the ideal range is between 10°C and 33°C.

 Working in Sections

Plastering is most effective when done in manageable sections. This allows your plastering contractor to focus on achieving an even finish without rushing.

Testing and Experimentations

Before starting on a prominent and unfamiliar wall, often a patch test on a smaller area may be undertaken to understand how the plaster behaves.

Safety First

Contractors should always wear gloves, goggles, and a mask to protect themselves from dust and debris during plastering.

 Exterior plastering, though intricate and complicated, can produce stunning and durable results when conducted with care and expertise. By understanding the techniques and following best practices outlined in this guide, you can be confident your plastering project is managed by your team with skilled expertise. Whether you're looking to renovate your home, renovate a new home or enhance the facade of a building, a well-executed exterior plaster application will undoubtedly stand the test of time.

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