Building a cob bench is a fantastic way to blend sustainability with craftsmanship.

Crafting a cob bench can enhance your outdoor space, providing both functionality and aesthetic appeal. In this blog post, we’ll walk you through the process of building a cob bench, from materials and preparation to finishing touches.

Why Build a Cob Bench?

Before diving into the construction process, let’s explore why a cob bench is a great choice:

• Sustainability: Cob is a natural, biodegradable material that has minimal environmental impact. Using local materials reduces transportation emissions and supports a circular economy.
• Durability: Cob is highly durable and weather-resistant when properly maintained, making it an excellent choice for outdoor furniture.
• Aesthetic Appeal: Cob benches have a unique, rustic charm and can be customized with various shapes and textures to fit your garden or outdoor space.

Materials and Tools

Materials:

• Clay: The primary binder for the cob mixture. You can source clay from local suppliers or use soil with a high clay content.
• Sand: Provides structure and prevents cracking. Clean, coarse sand is ideal.
• Straw: Adds strength and insulation to the cob mix.
• Water: To mix the materials into a workable consistency.

Tools:

• Shovel: For mixing and transporting materials.
• Wheelbarrow: For moving the cob mixture.
• Trowel: For shaping and smoothing the cob.
• Wooden Formwork: To shape the bench.
• Protective Gear: Gloves, eye protection, and appropriate clothing.

Step-by-Step Guide to Building a Cob Bench

1. Plan Your Bench Design

Before you start, sketch out your design. Consider the following:

• Dimensions: Decide on the length, width, and height of the bench.
• Shape: Traditional rectangular, curved, or custom shapes.
• Location: Choose a suitable spot in your garden or outdoor area.

2. Prepare the Site

• Clear the Area: Remove any debris, grass, or plants from the site where you’ll be building the bench.
• Level the Ground: Ensure the ground is level to provide a stable base for the bench.

3. Build the Foundation

• Create a Base: Lay down a foundation of gravel or small stones to improve drainage and prevent moisture-related issues.
• Construct Formwork: Build wooden formwork to outline the shape and dimensions of your bench. This will hold the cob in place while it dries.
• Alternately use a string line to guide where you will build the wall to.

4. Mix the Cob

• Combine Materials: In a wheelbarrow or on a tarp, mix clay, sand, and straw. A common ratio is 1 part clay, 3 parts sand, and a handful of straw.
• Add Water: Gradually add water to the mixture, blending until you achieve a consistency similar to thick bread dough. The mix should be moist but not too wet.

5. Build the Bench Structure

• Apply the Cob: Start applying the cob mixture to the formwork, layering it in sections. Press and compact the cob firmly to ensure it sticks together and fills gaps.
• Shape the Bench: Use a trowel to shape the bench’s seat and backrest. Smooth out any rough spots and refine the contours.
• Build in Layers: If needed, build the bench in layers, allowing each layer to dry slightly before adding the next.

6. Drying and Curing

• Allow to Dry: Let the cob bench dry slowly. Depending on the weather, this can take several weeks. Protect it from heavy rain and direct sunlight to avoid cracking.
• Cure the Cob: Once dry, you may apply a natural finish like lime plaster or a waterproof sealant to protect the bench from weathering and enhance its durability.

7. Finishing Touches

• Decorate: Add decorative elements such as mosaic tiles, stones, or other embellishments to personalise your bench.
• Test and Adjust: Once completely dry, test the stability and comfort of your bench. Make any necessary adjustments to ensure it meets your needs.

Maintaining Your Cob Bench

To ensure the longevity of your cob bench:

• Regular Inspections: Check for cracks or damage periodically. Repair any issues promptly.
• Clean Wisely: Avoid using harsh chemicals or high-pressure water. Instead, gently clean the bench with a damp cloth.
• Reapply Finish: Depending on the weather conditions and wear, you may need to reapply protective finishes every few years.

Render your Cob Bench

Rendering a cob bench not only enhances its aesthetic appeal but also provides protection against the elements, ensuring the longevity and durability of your creation. Whether you’re aiming for a rustic, natural finish or a more refined look, proper rendering will enhance both the function and appearance of your cob bench. This guide will walk you through the steps to achieve a professional and lasting finish on your cob bench.

Rendering serves multiple purposes for a cob bench:

• Protection: It shields the cob from moisture, UV rays, and physical wear.
• Aesthetic Enhancement: Provides a smooth, polished look or decorative finish.
• Durability: Increases the lifespan of the bench by reducing the risk of cracking and erosion.

Rendering can be undertaken a few ways:

• Lime Plaster: Traditional and effective, lime plaster allows the cob to breathe and provides excellent protection against the elements.
• Clay Plaster: Another natural option, clay plaster can be used if you prefer an alternative to lime plaster.
• Natural Pigments (Optional): For coloring your render, if desired.

Apply the Render

• First Coat: Apply a thin, scratch coat of render to the dampened cob surface. Use a trowel to spread a layer about 5-10mm thick. This initial coat helps the subsequent layers adhere better.
• Scratch the Surface: While the first coat is still wet, use a comb or the edge of a trowel to create a rough texture. This provides a key for the next layer to bond to.

Apply Additional Coats

• Second Coat: After the first coat has dried (usually 24-48 hours), apply a second, thicker coat of render. This coat should be smoother and about 10-15mm thick.
• Smooth and Finish: Use a trowel to smooth out the second coat, removing any trowel marks or imperfections. For a textured finish, you can use a sponge or brush to create patterns or textures as desired.

Curing and Drying

• Protect the Render: Protect the newly rendered bench from direct sunlight, heavy rain, or frost for at least a week. This prevents rapid drying, which can cause cracking.
• Maintain Moisture: Keep the render slightly damp during the curing process, especially in hot or dry conditions. Mist the surface with water if necessary to prevent it from drying too quickly.

Building a cob bench is a rewarding project that combines sustainability with craftsmanship. By following these steps, you can create a beautiful and functional piece of outdoor furniture that enhances your garden or outdoor space. Embracing natural materials and traditional techniques not only contributes to environmental conservation but also adds a unique touch to your home.

So gather your materials, get creative, and enjoy the process of crafting a cob bench that will serve as a lasting testament to your commitment to sustainability and craftsmanship.