Buy PDF & Cut List
Sponsored by Quikrete

Craft Your Own Indestructible Concrete Bench: A Definitive DIY Guide

Transform your outdoor living space with a custom-built concrete bench – a project that promises unparalleled durability, timeless style, and minimal maintenance. Unlike traditional wooden benches that demand seasonal care and can succumb to the elements, a carefully crafted concrete bench stands resilient against winter’s chill, summer’s heat, and everything in between. This comprehensive guide will walk you through the entire process, from gathering your materials to the final finishing touches, empowering you to create a beautiful and enduring piece of backyard furniture. While we provide a detailed blueprint for a sturdy, crack-free design, we also encourage you to infuse your personal creativity, experimenting with different forms, finishes, and inlays to build a garden bench that truly reflects your unique aesthetic.

Why a DIY Concrete Bench is the Ultimate Outdoor Seating Solution

Opting for a concrete bench goes beyond mere aesthetics; it’s an investment in longevity and robust functionality for your backyard or patio. Here’s why this project is a rewarding endeavor for any DIY enthusiast:

• Exceptional Durability: Concrete is inherently strong and capable of withstanding extreme weather conditions, heavy use, and the test of time. Once cast, assembled, and properly sealed, your bench will be virtually indestructible, offering years of reliable service without showing signs of wear and tear.
• Minimal Maintenance: Forget about sanding, staining, or covering your bench every season. A concrete bench requires little to no ongoing maintenance, freeing up your time to simply relax and enjoy your outdoor oasis. A quick wash is often all that’s needed to keep it looking pristine.
• Sustainable and Eco-Friendly: Concrete is a long-lasting material that reduces the need for frequent replacements, contributing to less waste over time. Moreover, if sourced responsibly, its components are readily available and can often be recycled.
• Unleash Your Creativity: While the core structure is robust, concrete offers incredible versatility for customization. From intricate inlays to various finishes (smooth, exposed aggregate), and even unique leg designs, you have the freedom to personalize your bench to perfectly complement your garden’s aesthetic.
• Cost-Effective in the Long Run: Although the initial material cost is comparable to some high-quality wooden alternatives, the extended lifespan and zero maintenance requirements of a concrete bench translate into significant savings over its lifetime.

Gathering Your Essential Materials and Tools: Setting the Foundation

A successful concrete project begins with the right materials and a well-equipped workspace. A quick trip to your local home center should provide everything you need. For this robust bench, we highly recommend Quikrete 5000 – a high-early strength concrete mix specifically engineered for projects requiring superior durability and a quicker setting time. This formula is crucial for ensuring your forms can be removed without compromising the integrity of your sturdy, crack-free bench.

Key Materials for Your Concrete Bench:

• Concrete Mix: Three 80-lb. bags of Quikrete 5000. These bags are heavy, so plan for transport or consider getting assistance. Do not substitute this mix, as its high early strength is vital for this project.
• Plywood for Forms:
  • Half sheet (4×4 ft.) of 3/4-inch plywood for the bench top ends and leg bases.
  • Quarter sheet (2×4 ft.) of 1/2-inch plywood for the flexible curved sides of the bench top.
• Reinforcement: Several 4-foot lengths of 1/2-inch steel rebar. The rebar provides tensile strength, significantly increasing the bench’s resistance to cracking.
• Form Release & Finish:
  • Acrylic wood finish or varnish (for sealing the forms).
  • Paste wax (for ensuring a smooth release of the concrete from the forms).
• Fasteners: A small box of 2-inch self-drilling wood screws (GRK fasteners or similar, known for strong hold and easy driving).
• Optional Inlay Materials:
  • Thin-set mortar (exterior grade).
  • Decorative stones or tiles (ensure consistent height for a level surface).
  • Grout (matching your inlay design).
  • Grout and stone sealer.
• Adhesive: Landscape block adhesive (for final assembly of bench components).
• Protective Sealer: Concrete sealer (to be applied after curing for long-term protection).

Essential Tools You’ll Need:

• Mixing Tools: A sturdy mixing tub or a wheelbarrow, a shovel, and a garden hoe for thorough concrete mixing.
• Finishing Tools: A finishing trowel for smoothing the concrete surface.
• Cutting Tools: A table saw or a circular saw with a guide for precise, straight cuts on plywood.
• Assembly Tools: A drill/driver for screws, various clamps to hold form pieces during assembly.
• Measurement Tools: Tape measure, pencil, and a scribing tool (easily made from a scrap of wood).
• Rebar Bending Tools: A sturdy anchor point like a fence post or a rebar bender.
• Demolding & Finishing:
  • Utility knife (for scoring plastic inserts).
  • Pliers (for removing inserts).
  • Abrasive material like an old 100-grit sanding belt or a tile-smoothing stone for refining edges.
  • Wire brush attachment for a drill (optional, for exposed aggregate finish).
  • Garden hose with a firm spray nozzle.
• Safety Gear: Always wear protective clothing, sturdy gloves, and most importantly, protective eyewear when handling wet concrete and operating power tools.

The estimated cost for these materials, excluding any specialized inlay options, is approximately $75, making this a highly affordable and rewarding DIY project.

Safety First: Important Precautions When Working with Concrete

Working with concrete can be a straightforward process, but it requires adherence to essential safety practices. Wet concrete is alkaline and can cause skin irritation or chemical burns upon prolonged contact. Dust from dry concrete can also be an irritant. Always prioritize your safety:

• Eye Protection: Wear safety glasses or goggles at all times to protect against splashes and airborne particles.
• Hand Protection: Use heavy-duty, waterproof gloves to prevent direct skin contact with wet concrete.
• Skin Protection: Wear long-sleeved shirts and long pants. If skin contact occurs, wash the affected area thoroughly with clean water.
• Respiratory Protection: When mixing dry concrete, especially in enclosed spaces, consider wearing a dust mask to avoid inhaling cement particles.
• Lifting Safely: Concrete bags are heavy. Lift with your legs, not your back, and get assistance when moving heavy items to prevent injury.
• Ventilation: Work in a well-ventilated area, especially when mixing concrete or applying sealers and varnishes.

Step-by-Step Construction Guide: Building Your Concrete Bench

Follow these detailed steps carefully to ensure a successful and satisfying build. Precision and patience are your best tools throughout this process.

1. Constructing the Bench Top Form: The Blueprint for Your Bench

The foundation of your bench’s aesthetics and structural integrity lies in the quality of its forms. Refer to detailed drawings (typically found in the PDF plan, which we highly recommend purchasing for precise dimensions) for the exact measurements. Use a table saw or a circular saw with a guide to achieve consistently straight cuts, which are crucial for a professional finish. Assemble the outer form using 2-inch wood screws, ensuring all parts are securely fastened. Clamps will be invaluable here, helping to hold pieces in place and gently bend the 1/2-inch plywood sides to create the desired curve.

For the internal curved insert, cut a 41-inch by 10-1/2-inch piece from 1/2-inch plywood. This flexibility is key to achieving the elegant curve. Place this insert temporarily into the assembled form. To accurately mark the inner edge for the curved shape, create a simple scribing tool: take a scrap of wood, drill a hole 3-1/2 inches from one edge, and insert your pencil or marker. Run this tool along the outer edge of the form while the pencil traces the curve on your insert. Cut the insert precisely along this marked line, then glue and screw it to the base of the form, ensuring it’s perfectly aligned and secured.

2. Preparing the Forms: Ensuring a Flawless Concrete Release

Proper preparation of your forms is critical for achieving a smooth concrete surface and effortless demolding. First, thoroughly seal the entire interior surface of the form with an acrylic varnish. This prevents the concrete from absorbing moisture from the wood, which can weaken the surface and make demolding difficult. Allow the varnish to dry completely according to the manufacturer’s instructions. Once dry, apply a thin, even film of paste wax over the varnished inner form. This acts as a release agent, ensuring the concrete doesn’t stick and allowing the form to be removed cleanly, revealing a smooth, unblemished concrete surface.

3. Reinforcing with Rebar: Adding Structural Strength

Concrete is strong under compression but relatively weak under tension. Rebar (reinforcing bar) provides the necessary tensile strength, preventing cracks and significantly increasing the bench’s overall durability and load-bearing capacity. Measure and cut the 1/2-inch steel rebar to fit within the forms, ensuring each length is approximately 1-1/2 inches shy of each end of the form. This allows for proper concrete coverage around the rebar, preventing rust and spalling. Carefully bend the rebar into a gentle curve that precisely follows the contour of your bench top form. A sturdy fence post, a rebar bender, or even a strong vice can be used to achieve the desired shape. Take your time to get the curves consistent.

4. Constructing the Leg Forms: Designing Unique Supports

The legs are just as important as the bench top for stability and aesthetics. Cut the bases for the leg forms from 3/4-inch plywood. For a distinctive leg design, consider using a plastic insert. The original project used a 4-inch Snap Coupler for drainage pipe (which has an actual outside diameter of 5 inches) from a hardware store. Center this insert on your plywood base and trace its outline. You can experiment with various shapes – a simple round, an oval, or even custom geometric designs. The key is to create a visually appealing and stable support structure.

Next, cut and assemble the remaining leg form pieces according to the dimensions provided in your plans (e.g., Fig. C below in the original drawings). Precision here ensures a snug fit for the plastic insert. Once assembled, use adhesive caulk or construction adhesive to securely glue the plastic insert into its designated place within the leg form. Allow this adhesive to dry overnight to ensure a strong, stable bond before proceeding. Just like the bench top form, brush on an acrylic varnish to cover the entire inner surface of the leg forms. Once the varnish is completely dry, apply a generous film of paste wax to these inner surfaces to facilitate a smooth release of the concrete legs.

5. Mixing the Concrete: Achieving the Optimal Consistency

The success of your concrete pour hinges on achieving the perfect mix consistency. Empty one bag of Quikrete 5000 into your mixing tub or wheelbarrow. Gradually add water while mixing thoroughly with a shovel or garden hoe. The goal is a consistency similar to thick oatmeal or peanut butter – it should hold its shape when shoveled but spread easily with a trowel. A runny mix is detrimental, as it will weaken the final product and compromise the bench’s integrity. The mix needs to be thick enough to keep its aggregates (sand and stones) and the rebar in suspension, preventing them from settling to the bottom. Remember your safety gear: gloves and protective eyewear are essential when working with wet concrete.

6. Pouring the Bench Top: Filling the Primary Form

With your concrete mixed to perfection, it’s time to pour the bench top. Carefully shovel the concrete into the form until it’s about two-thirds full. Avoid overworking the concrete at this stage; less manipulation is often more beneficial, preventing segregation of aggregates. Once the form is partially filled, gently tap around the outside of the forms with a rubber mallet or hammer. This vibration helps to bring trapped air bubbles to the surface, resulting in a denser, smoother finish, and also aids in settling some of the stones in the mix towards the form’s bottom (which is the top of the bench once flipped). Aim for about 20 taps per side and bottom.

Next, carefully lay the pre-bent rebar into the partially filled concrete. Ensure it’s centered and fully submerged. Immediately after placing the rebar, continue filling the form to the very top with the remaining concrete. If you need to mix a second bag, do so promptly. Quikrete 5000 has a relatively fast setting time, especially in warmer weather (it can begin to set in as little as an hour), so it’s crucial that any subsequent pours are done in closely timed sessions to ensure a strong monolithic bond between layers. Level the concrete flush with the top of the form using your finishing trowel, then gently tap the form again to further consolidate the concrete and release any remaining air. Finally, place the entire pour in the shade and cover it with a plastic tarp. This prevents rapid drying, which can lead to cracking. Never allow the concrete to cure in direct sunlight.

7. Pouring the Legs: Completing the Structural Components

While the bench top begins its initial cure, mix the remaining concrete for the legs, following the same consistency guidelines as before. Fill the leg forms carefully, ensuring even distribution. As you fill, gently tap the sides of the leg forms. Because the leg forms are smaller and often simpler in shape, you’ll need fewer taps than for the main bench top – about half as many should suffice to release air bubbles and consolidate the mix effectively. Ensure the concrete is level with the top of the forms. Once poured, cover the leg forms with plastic and allow them to cure in the shade alongside the bench top.

8. Demolding the Bench Top: The “Green Stage”

Patience is paramount during the demolding process. After approximately 40 hours, the concrete will be in its “green stage” – strong enough to handle but still relatively fragile. Begin by carefully unscrewing one side of the bench top form at a time. Work gently and methodically. Once the sides are detached, carefully tip the bench top onto its edge. The base portion of the form, due to its larger surface area, might be stubborn. Apply gentle, consistent taps around the perimeter of the base with a rubber mallet, working slowly to encourage its release. Avoid forcing it, as this can damage the still-curing concrete. Take your time; the goal is a clean separation without marring your newly cast bench top.

9. Revealing the Finish: Smooth or Exposed Aggregate?

Once demolded, inspect the surface of your bench top. Depending on your form preparation and concrete mix, it might be perfectly smooth, or it could have a slightly rougher texture. A smooth finish can be left as is, allowing the concrete to continue hardening to its final strength. However, if you prefer a more rustic, textured look – an “exposed aggregate” finish – you can gently reveal the small stones within the concrete. As demonstrated in the original project, a wire brush attachment on a drill can be used to carefully remove the thin layer of smooth cement paste, exposing the underlying aggregate. Exercise extreme caution and a light touch to preserve the integrity of the surface. After achieving your desired finish, hose down the bench top with a firm spray of water from a garden hose to clean off any loose particles and aid in the continued curing process. Allow the surface to harden for another couple of days.

10. Demolding the Legs: Freeing the Supports

Two days after the concrete pour, your bench legs should be ready for demolding. Begin by carefully prying the edges of the plastic inserts within the leg forms. Be extremely cautious not to mar or chip the concrete surface. If the plastic is particularly stubborn, you can use a utility knife to carefully score the plastic itself, which helps to loosen its grip on the concrete. Once sufficiently loosened, use pliers to gently pull the plastic insert out of the form. This meticulous approach ensures a clean removal and a perfectly formed leg.

11. Refining the Edges: Achieving a Polished Look

After demolding both the bench top and the legs, you might find some slightly rough or sharp edges. To achieve a smooth, professional finish and prevent snags or discomfort, these edges need to be refined. An abrasive material works best for this. An old 100-grit sanding belt can be effectively used, or a tile-smoothing stone offers a similar result. Gently work around all the edges of both the bench top and the legs, smoothing out any imperfections until they are pleasant to the touch and visually appealing. This step adds a crucial level of craftsmanship to your project.

12. Adding Custom Inlays (Optional): Personalizing Your Bench

This is where your bench truly becomes a unique masterpiece! For those who wish to add a personalized touch, a decorative inlay can elevate your concrete bench to a work of art. Gather your chosen inlay materials: a thin-set mortar specifically designed for exterior applications, and an assortment of stones or tiles. These can be purchased from a local tile supply store or even collected from nature, as long as they are relatively consistent in height to ensure a level final surface. Mix the thin-set mortar to a consistency similar to peanut butter. Before permanently setting your stones, it’s an excellent idea to do a “dry run” – arrange your design on a separate surface or even temporarily on the bench to visualize the pattern and orient your mind to the puzzle-like task. Once you’re satisfied with your design, begin applying the thin-set and carefully setting each stone into place. Work systematically, pressing each piece firmly into the mortar.

13. Sealing & Grouting the Inlay: Protecting Your Design

As you set the stones, immediately wipe off any drips or excess mortar from the surface of the stones. Once set, thin-set mortar is extremely difficult to remove without damaging the inlay. Allow the thin-set to cure completely, typically overnight. The next day, you’ll prepare for grouting. First, apply a grout and stone sealer to the tops of your inlay stones. This crucial step creates a protective barrier that will prevent grout haze from sticking to the surface of your decorative elements, making cleanup much easier. Be careful to apply the sealer only to the tops of the stones, avoiding the spaces between them where the grout will go. Allow the sealer to dry as per product instructions, usually another day, before proceeding with grouting.

Once the sealer is dry, prepare your grout according to the manufacturer’s instructions, again aiming for a peanut butter-like consistency. Using a rubber float, push the grout firmly into all the spaces between the stones, ensuring complete coverage and no voids. Allow the grout to set for approximately one hour. After this initial setting period, use a damp sponge to gently wipe off the excess grout from the surface of the stones and smooth the grout lines. It’s important not to use too much water during this cleaning phase, as excessive water can weaken the grout. Continue wiping and smoothing until the inlay is clean and the grout lines are uniform and well-defined. Once cleaned, set the entire project aside for a few days to allow the grout to fully cure and harden.

14. Final Assembly & Long-Term Protection: Bringing Your Bench to Life

After all components have fully cured, it’s time for the final assembly. Begin with a “dry run” – place the bench top onto the legs without adhesive to confirm alignment and fit. Once satisfied, mark the exact locations where the legs meet the bench top with a pencil. Then, apply a generous amount of exterior-grade landscape block adhesive to the mating surfaces of the legs and carefully position the bench top. Press firmly to ensure good contact. Allow the adhesive to set for a full day before attempting to move or use your newly assembled bench. This ensures a strong, lasting bond.

For ultimate protection against moisture, freeze-thaw cycles, and general wear, it is highly recommended to apply a high-quality concrete sealer to the entire surface of your bench (top and sides) after approximately four weeks of curing. This allows the concrete to fully hydrate and strengthen before being sealed. A good sealer will penetrate the concrete, forming a barrier that repels water and stains, further extending the life and beauty of your indestructible outdoor bench. Now, settle back and enjoy the fruits of your labor! Looking for more Quikrete projects to enhance your home? Consider upgrading your garden with a durable Quikrete walkway, or explore other creative concrete applications for your landscape.

Conclusion: Enjoy Your Masterpiece!

You’ve successfully built an outdoor concrete bench that will stand the test of time, providing a comfortable and stylish seating solution for generations. This project is a testament to the power of DIY – combining strength, elegance, and personal craftsmanship. Each step, from mixing the concrete to perfecting the inlay, contributes to a final product that is not only functional but also a beautiful addition to your outdoor space. Embrace the durability and low-maintenance lifestyle your new concrete bench offers, and relish in the satisfaction of having created something truly special with your own hands. Happy relaxing!

— David Radtke, Contributing Editor

This is a sponsored conversation written by me on behalf of Quikrete. The opinions and text are all mine.