Render with sand and cement has always been and will always be a winner when it comes to applying a decorative and protective coating to masonry walls. The method combines sand, cement and water to form a “paste” that is built up in layers to create a smooth or textured finish. This article will take a closer look at sand and cement rendering, suitable sands, cement-sand proportions and mixing, the mixing process, and sand cement rendering techniques.

What is Sand and Cement Rendering?

Sand and cement rendering is the name given to a finish that is applied to the walls of houses to provide protection against the elements, and to make a good-looking and durable surface. Along with other functions, it serves to protect the wall at the building’s edge, it can serve as a decorative function, and it can be used as a base for paint or other coatings. The combination is generally applied in two or three layers, each serving a different function. Australian Rendering Company is a market leader in professional cement rendering services which apply clean, robust rendered finishes to homes and buildings throughout Melbourne.

Sand and Cement Rendering Supplies Needed

Below is what you will need to finish sand and cement rendering:

Materials for Successful Sand and Cement Rendering

• Cement: Usually ordinary Portland cement is used, as this provides strength.
• Sand: Sand type does matter. Sharp sand is often the choice, but the operator must understand exactly what he is getting. We’ll go into greater detail about this later.
• Water: Use clean potable water to mix the render.
• Additives (optional): Plasticizers, retarders, or accelerators may be added to change the properties of the render, such as workability or setting time.

List of Tools for Sand and Cement Rendering

It’s always easier and faster to render if you have the right tools. Essential tools include:

• Mixing tools: Wheelbarrow or mechanical mixer.
• Application tools: Trowels (different sizes), hawk and floats.
• Preparation: Wire brush, scraper, and pressure washing.
• Leveling tools: Buckets, measuring tools, and the spirit level.
• Safety equipment: Gloves, goggles, and dust mask.

Selecting the Correct Sand for Rendering

The quality and longevity of the render depend a great deal on the quality of sand used. The composition of the sand used varies widely, even in the same district or country, but the most desirable kind to use is a clean sharp silica sand, with fine grains which are angular. In other words, the sand with which the best results are obtained is that in which the particles are about equal in size, and have corners, and when examined under a magnifier appear as a number of little prisms. However, it is seldom that such a sand is to be had, sand with rounded particles or with superfluous fine particles being more common than sand such as described.

Types of Sand

• Sharp Sand: With angular grains, its coarse texture makes it both very strong and hardwearing. It is angular in shape and the sharp edges assist fine particles to bind with cement, rendering it a versatile material. Another name for sharp sand is coarse sand.
• Soft Sand: Also known as builder’s sand or fat sand, soft sand has a finer granule than coarse sand and is mixed with lime to obtain railings. It is not as well-suited to rendering as it has less cementitious properties and this can then lead to a weaker render that is more susceptible to cracking.
• Washed Sand: This is sand that has been washed to remove any silt and clay particles, as these are too fine to bind the sand and cement together. Sand should be clean when rendering.

Sharp Sand for Rendering

That’s right, the preferred option for rendering is sharp sand. It has angular grains which lock tightly together and prevent aggregate from moving, creating a stronger key for cement to adhere to, giving a more durable finish. The netlike texture also minimizes shrinkage and cracking.

Can you use sharp sand for rendering?
Mostly sharp sand is more than ok; it is the preferred choice to produce a good render. It is fine if the “sharp sand” you are obtaining is just that very small sharp grit and be sure it is clean, no clay or organic matter. Contaminants can weaken and disfigure the finish.

What kind of sand for rendering?
Sharp sand is the best choice for rendering uses. But it can be beach sand, whatever, just depends on what finish you want and what kind of concrete you are doing. By working with a rendering contractor, you can find the right sand for your project.

Sand Cement Render Mix Ratio

The amount of sand to cement is an important factor in determining the strength, workability, and finish of the application. The ratio will determine the render’s flexibility (the more aggregate, the more flexible it should be), its strength and how well it sticks to the surface.

Common Standards for Sand and Cement Render Mix Ratio

• Base Coat (Scratch Coat): It is typical to use a 4:1 ratio of sand to cement for the base coat. This coat should be firm and give a good key for later coats.
• Second Coat (Float Coat): The second coat is usually applied with a ratio of 5 parts sand to 1 part cement (5:1). This layer is meant to even out the surface, so it can ready itself for the final layer.
• Top Coat (Finish Coat): For a smoother finish, the top coat may be proportioned in a mix of 6 parts sand to 1 part cement (6:1). The precise ratio can be affected by desired texture and the types of sand used.

Although these may vary, adjustment of a particular sand and cement mix ratio for rendering may be required according to the type of sand and cement available. It is advisable to make a test batch to test its working consistency and adhesion to surfaces.

• Strength: The stronger the concrete, the stronger the render, although, it may also be more susceptible to cracking. The strength will be less as the cement content is decreased, but workability is increased.
• Workability: The proportion of sand to cement also determines how easy the render is to work with. An over-rich mix may be unworkable, and an over-lean mix may be weak and friable.
• Texture: The sand used and also the render mix proportion can affect the finish of the render. The shinier the finish, the lighter the sand and the more sand to cement ratio you will find.

Mixing Sand and Cement Render

What mixing sand and cement render ratio should be for the scratching coat? How to mix sand and cement render? Mixing the sand and cement render is so simple, as long as you have the right known ratio.

Step-by-Step Mixing Guide

1. Measure Out the Materials: Measure the sand and the cement with either a gauging trowel or a bucket, following the prescribed mix ratios. So, for a 4:1 mix, that’s 4 parts sand and 1 part cement.
2. Mix the Dry Ingredients: In a wheelbarrow or a mechanical mixer, mix the sand and the cement to a uniform color and texture. This is to ensure that the cement is thoroughly proportioned in the sand.
3. Pour in Water Slowly: Add water slowly, still mixing. The volume of water required in the mix depends on the moisture content of the sand used and the thickness of the render. You want a mixture that is somewhat plastic and workable, but not extremely wet or soupy.
4. Combine Well: Continue to mix the render well, until all ingredients are well-mixed together and the rendered material has no lumps. The dough should be a uniform color and texture.
5. Test for Consistency: Test the render mixture consistency by scooping some onto a trowel and then turning the trowel upside down. The render should stick to the trowel and not run or fall. If it’s too dry, add more water. If it’s too wet, add sand and cement in the right ratio.

Tips for Mixing Sand and Cement Render

• Clean Water: Always use fresh, clean water when mixing render. Hardness or impurities in the supply may alter the strength and lasting power of the render.
• Careful with Over Mixing: Over-mixing can damage render, making it difficult to work with. Stir just until ingredients are well combined.
• Reason for ‘Batch Mixing’: As a rule of thumb, the render is best mixed in small batches so that it can still be used. Be careful of overtaxing if using a mechanical mixer.

Sand and Cement Render Application

Sand and cement render application comprises the preparation of the working surface, rendering in coats, and the decoration of the surface until the finish is achieved.

Surface Preparation

1. Clean the Surface: Remove any loose or peeling material with a wire brush or scraper. This will help the render to bond well.
2. Wash the Surface: Clean away any dirt, dust, or grease with a power washer. This will increase the adhesion between the render and the substrate.
3. Wet the Surface: Dampen the surface with water before rendering. This will stop the substrate from drying out the render too rapidly, which will lead to cracking.
4. Brush Bonding Agent (Optional): Where it is required to improve adhesion of the render to the background surface, an appropriate bonding agent may be applied. This would be especially beneficial for smooth or nonporous surfaces.

Application Process

1. Apply First Coat (Scratch Coat): Spread a thin and even layer of render onto the target area with the trowel. The scratch coat should be 6-10mm thick. Then run the trowel horizontally across the render surface and make scratches. This way, the second layer will have something to grab onto when you apply it.
2. Cure the First Coat: Let the scratch coat cure for 24 to 48 hours before adding the second coat. Moisten the surface occasionally while curing, by means of water spray.
3. 2nd Coat (Float Coat): Apply the second coat of render to the profile with a trowel. The thickness of the float coat is about 6-10mm. Level the surface with a float and fill in any voids. This coat needs to bring everything to a flat surface.
4. Let the Second Coat Cure: Make sure to let your float coat cure for 24-48 hours before applying another coat. Maintain moisture on the surface while curing.
5. Top Coat (Finish Coat): Use a trowel to spread an even layer of render over the surface to be cement rendered. The thickness of the texture coat applied will determine the texture and pattern of the finish. Finish any texture by means of a float, sponge or other suitable tool. Some of the popular textures include smooth, textured, and patterned finishes.
6. Curing the Top Coat: The cure time for the finish coat shall be no less than seven days before painting or installing other finishes. During curing, keep the surface wet to prevent cracking.

Applying Sand and Cement Render – A Few Hints and Tips

• Work in Batches: Work in batches and you just have to keep the entire render manageable. The render is laid on one strip at a time and followed with the next.
• Apply Even Pressure: Apply uniform pressure while spreading the render so it spreads evenly. This will prevent changes in thickness and appearance.
• Keep Your Tools Clean: It sounds simple but it’s amazing how easily you can forget to wash your float and other tools so that the render doesn’t stick to them. Wash your tools with water and a sponge periodically.

Finishing Methods

Finishing methods include the following, for different textures and looks. The following are some common choices:

• Steel Troweled Finishes: A smooth finish can be achieved with a steel trowel. This is a contemporary finish, perfect for modern buildings.
• Textured Finish (Sponge/Float): Texture the surface with a sponge, float or other texturing tool. This finish is ideal for old or rural buildings.
• Textured Finish (Roller/Stencil): Use a textured roller or stencil to create a decorative textured surface.

Common Problems and Solutions

There can still be some issues with sand and cement render even if you prepare and apply it with great care. Here are some frequent problems and their solutions:

• Cracking: Formation of cracks can be driven by shrinkage, stretching or displacement of the base. Cracking can also occur if the right ratio is not kept, or if the surface is not prepared correctly, or if it is less than saturated as it cures. If crevices develop, simply use a flexible sealant or patching compound to repair them.
• Delamination: It is the loss of bond or separation of the coating from the base. To avoid delamination, it is important that the surface is clean and well-prepared before the render is applied. A primer may be additionally used to enhance the bond.
• Efflorescence: Efflorescence is a white powdery salt deposit that is visible on the outside of the render. It results from the salts coming to the surface. Efflorescence can be avoided by using clean water when mixing the render and applying a waterproof coating to the surface.

Is Sand and Cement Render Waterproof?

Sand and Cement Render is NOT waterproof as standard. Even though it has a little water resistance, it can get wet over time because it is porous. To make the sand and cement render waterproof, it would need a waterproof cladding like a waterproof coating or a membrane. This will stop water from entering the render and embedding itself into any porous substrate.

How Long Does Sand and Cement Render Last?

The life of the render is dependent on a number of factors such as the quality of the materials used, the method of application, and the location of the render. Sand and cement render can remain in good condition for years if done properly and well maintained. Its life can be prolonged by periodic checks and repairs.

Is It Possible To Paint Sand And Cement Render?

Yes, you can paint sand and cement render. But do be sure the render has cured totally before painting. Paint with a breathable paint made especially for use on masonry. This is to give an escape route for any moisture from the render (render should rarely be very wet anyway) and stop the paint blistering. We offer a 7-year guarantee on our rendering, providing sleek, incredibly resilient finishes that last and last.

Pricing Sand and Cement Rendering

The price of sand and cement rendering depends on the size of your area to be rendered, the type of sand and cement, and the complexity of the job. Getting quotes from several rendering professionals can give a better idea of the price.

Factors Affecting the Cost

• The Size of the Area: The bigger the area, the more you will be charged.
• Type of Materials: What’s in the sand and cement also contributes to the cost. Sharp sand usually costs a bit more than soft sand, and certain cements may increase prices.
• Project Complexity: Projects on the more complex side, from designs to tighter spots, will cost more than the simpler variety.
• Cost of Labor: The cost of hiring a professional rendering contractor may vary according to your geographical location and the contractor’s level of experience.

Cost-Saving Tips

• Prepare the Surface Yourself: Provide labor in preparing the substrate by yourself. This can include cleaning the surface, removing loose material and using a bonding agent.
• Get Many Quotes: It is always good to receive quotes from several rendering companies to have a pool of quotes to compare from. Study the quotes meticulously and select a contractor who can give you a price and quality balance.
• Opt for an Easy Finish: A simple finish can be less expensive. Complex finishes such as elaborate designs or textures will tend to be more expensive.

Advantages of Sand and Cement Rendering

There are many advantages of sand and cement rendering, some of which are:

• Protection: It helps protect the brick or block work beneath it from the weather, which can erode the surface over time.
• Aesthetics: It’s a good way to cover up an unsightly building with a smooth, uniform surface that can be painted or finished in any number of ways.
• Durability: It offers a durable and long-lasting finish that resists mildew and wear and tear over time.
• Applicability: It is applicable to multiple facades, such as brick, block and concrete.

Other Kinds of Rendering Besides Sand and Cement

Although sand and cement is used most commonly, other types of render can be used including the following:

• Acrylic Render: Acrylic render is a type of polymer-modified render that has a higher flexibility and greater resistance to cracking as compared to sand and cement render. It’s also available in a variety of colors and textures. Australian Rendering Company offers professional acrylic rendering throughout Melbourne, with a range of finishes to design to your need.
• Lime Render: Lime render, made from lime, sand and water, is a render of old. It is a more breathable alternative to sand and cement render and a suitable option for older properties.
• Polymer Render: Polymer render is a polymer-cement-based render. It is a more durable alternative to Sand & Cement Render that’s less prone to cracking.

Is Sand And Cement Render Cheaper Than Acrylic?

Sand and cement render is typically more cost-effective than acrylic render. The price difference has to do with the fact that acrylic-based renders incorporate polymers and other additives that make them more expensive. But the actual cost will vary according to the brand, quality and quantity of material used in addition to the labor involved.

Cement Render Vs Acrylic Render: Which One?

Selecting a Rendering Company

It’s a no-brainer to ensure you hire a rendering contractor who is experienced, qualified, and has appropriate insurance. Here’s how to decide on a rendering contractor:

• See Who They Are: Verify the contractor is licensed and fully insured. This will cover you in the event of accidents or damage.
• Request References: Request the contractor for references of anything they have worked on. Having a reference list, call a few of the contractor’s references to find out about their experience.
• Request a Written Quote: Request a written quote from the contractor with a line-item breakdown of the total cost. Obtain multiple quotes for the project, comparing prices between contractors.
• Check Reviews: Read reviews from the internet to see what people are saying about the contractor.

You can select a good rendering contractor at a reasonable cost with these useful tips.