What To Do With Concrete Blocks? | Smart Build Ideas

Concrete blocks, also called CMUs or cinder blocks, are rugged, cheap, and endlessly reusable. Maybe you have a stack from a past project, or picked some up for pocket change. Instead of letting them sit, you can turn those blocks into projects that look clean, feel solid underfoot, and hold up to weather. This guide gives you practical builds, clear steps, and safety notes from real-world use.

You’ll see where hollow units shine, when solid caps make more sense, and how to start on a flat base so things stay put. You’ll also learn which blocks to choose for edging, seating, storage, planters, and more. The ideas below mix weekend builds and faster wins so you can pick based on time, tools, and budget.

If you’re new to blocks, skim the table first. It lists common unit types, the jobs they match, and quick tips. For technical details such as shapes and nominal sizes, the industry’s typical sizes and shapes sheet is a handy reference.

What to do with concrete blocks at home

Raised bed planters that drain well

Blocks make planters that heat up fast in spring and last for years. Stack two courses on compacted gravel, align the cells outward for pocket planters, or inward for a smooth face. Sweep in sand between courses for friction. Line the interior with weed-barrier fabric and fill with a soil blend. Many university extensions accept concrete blocks for food gardens; see this raised bed materials guidance for a balanced overview.

Steps

• Set a level base: rake the footprint, add 2–3 inches of compacted gravel, and screed flat.
• Dry-lay the first course in running bond. Tap into line with a rubber mallet and a straightedge.
• Stack a second course. Pin corners with construction adhesive or mortar if kids and pets will bump it.
• Cap with solid blocks or pavers for a smooth edge and easier cleanup.

Fire-pit surround that stays tidy

Use blocks to create a circular or square surround for a metal bowl or a ring lined with firebrick. Regular hollow blocks can crack under direct flame or repeated high heat, so keep them as the outer wall and line the burn area with a steel insert or refractory brick. For safe spacing, fuels, and clearances, review NFPA’s fire pit safety tips.

Steps

• Mark a circle with string and a stake, or square it with a tape and right-angle triangle.
• Excavate sod within the outline and add a compacted gravel base.
• Set a first ring of blocks tight and level. Check lines every few pieces.
• Add a second course, staggering joints. Drop in the steel insert or firebrick-lined ring.

Garden steps and landings

Solid caps over a base of hollow units make stout steps. Keep each tread flat and consistent. A slight pitch forward sheds water. Where soil is loose, add geotextile under the base gravel so the step doesn’t settle.

Layout tip

Use a 6–7 inch rise with an 11–12 inch tread for a natural stride. On long runs, break the flight with a landing built from a shallow block pad.

Quick benches and outdoor tables

Two uprights with a timber or concrete cap create instant seating. For comfort, set uprights about 16–18 inches high and 14–16 inches deep, then add a slab, paver, or sanded 2× lumber across the top. If you prefer no wood, lay cap blocks flat as the seat and glue them to the uprights.

Make it durable

Glue contact points, tuck a thin bead where cap meets upright, and add felt pads under indoor versions to protect floors. Outside, a bead of masonry sealant along the top sheds water.

Tool storage and garage fixtures

Blocks shine in the shop. Stack columns and span them with 2× lumber for adjustable shelves. Build a saw stand with blocks as legs and a plywood top, or a rolling base by trapping a dolly between courses. Since blocks are heavy, the stand damps vibration for cleaner cuts.

Safety first

Wear gloves when handling rough faces, and eye protection when drilling or cutting. Blocks are dense; lift with a flat back and bent knees, or team up for stacks above waist height. Store stacks no higher than you can control easily.

Safety and prep before you start

Good prep makes every project feel easy. Start with a flat, compacted base of gravel or sand so your first course sits true. A long level and a straightedge help keep things aligned. Where a wall backs soil, step the base in shallow terraces instead of one big lift. Add drains behind taller planters so water can escape.

Pick the right unit. Hollow units keep weight down and accept rebar or soil in the cells. Solid caps give clean tops on steps and benches. Textured faces hide scuffs in high-traffic spots. For a refresh on options, that NCMA sizes and shapes document shows common configurations.

Mind heat, weight, and water. Keep standard blocks out of direct flame. Don’t overhang caps more than a couple inches. On patios, slip a bit of foam sill gasket under indoor stands to protect tile or wood. In freeze-thaw zones, set exterior work on free-draining base material to reduce heaving.

Things to do with concrete blocks outdoors

Clean edging that guides mowers

Lay a single course of blocks flush with the lawn edge so your mower wheel rides the hard border. Flip blocks so the hollow cells face sideways and backfill with small stone. The stone adds mass and drains after rain.

Mailbox or parcel stand

Stack a narrow pier, glue courses, and bolt a treated plank across the top for the box. For a package shelf, widen the pier and add a paver cap. Where wind is strong, drop a short length of rebar into the cells and fill with gravel for ballast.

Covered grill station

Blocks make a stable base for a small grill on pavers. Build a U-shaped stand, add a paver or slab top, and leave a rear gap for airflow. Keep a non-combustible buffer around any heat source and use a steel or stone surface where the grill rests.

Compost bin that breathes

A three-sided bin with a removable front course turns easily and doesn’t rot. Leave a finger-width gap between blocks for air, or drill a few small holes in a cap for ventilation near the top. If pests are common, line the inside with hardware cloth before you stack.

Potting table with a hose shelf

Set two short piers and span them with a concrete cap or sealed board at waist height. Tuck a hose in a lower course, and screw hooks to the cap for hand tools. Add a piece of scrap PVC set into a cell for a quick brush holder.

Wildlife waterer or birdbath base

Glue two or three caps, then set a shallow bowl on top. Place near shrubs so birds have shelter, but keep a clear sightline so cats don’t ambush. Refresh the water often to keep things clean.

Tools and materials that help

You can build almost every project here with a shovel, hand tamper, level, tape, and rubber mallet. A speed square helps mark cuts. For glue-up, grab a construction adhesive rated for masonry and a caulk gun. A cheap diamond blade in a circular saw scores blocks for small notches; a rented block saw speeds big jobs. Keep extra sand or screenings for bedding, and a few pavers or caps to finish exposed tops.

Project planner: time, blocks, and budget

Use this quick planner to gauge effort. Quantities assume standard units and simple layouts. Adjust for curves, slopes, and caps.

Weather moves and settling

Expect a small amount of movement as soil cycles from wet to dry. After the first big rain, check level across caps. If a corner sinks, pry up that side and add a handful of screenings under the low spot. Brush jointing sand into wider gaps so weeds have less to grab. In freeze-thaw zones, keep the base free-draining and pitch surfaces so water leaves the work. A spring tune-up keeps everything square and tight for the long haul.

Cutting, fastening, and finishing tips

Clean cuts without a big saw

Score a line with a diamond blade, then tap along the score with a cold chisel until the block splits. For notches, score both faces and nibble the waste in shallow passes. Wear a dust mask and eye protection. Wet-cutting outdoors keeps dust down.

Fast bonds that don’t ooze

Use a thick bead of masonry adhesive near the block edges, then add a thinner bead inside. Press, twist a touch, and hold for a few seconds. Wipe squeeze-out at once. For permanent work, mortar gives the strongest bond but takes more time and cleanup.

Simple finishes that look polished

Paint with mineral or masonry paint for a breathable coat that resists peeling. A color wash softens new work so it blends with older patios. If you like raw block, brush off dust and seal splash zones so mud and leaf stains rinse away.

Common mistakes to avoid

• Skipping the base. A wavy first course makes every course above it a fight.
• Leaving no drainage behind planters. Trapped water will push on the wall.
• Overhanging caps too far. Keep the lip small so it won’t crack under weight.
• Placing regular blocks in direct flame. Use a steel insert or firebrick liner.
• Stacking tall without reinforcement. Keep freestanding features low unless you’re mortaring and tying into a footing.

Care that keeps projects looking new

Sweep grit from treads and tops so abrasion doesn’t dull the face. Rinse off de-icing salts in spring. Pull weeds that germinate in joints, or brush in polymeric sand for a cleaner look. Where soil splashes, add a drip edge of gravel so the face stays clean after storms.

Ready-to-build checklist

• Measure twice and plan courses in running bond so joints stagger nicely.
• Gather base material: gravel or screenings, geotextile if soil is soft.
• Lay out edges with string lines, paint, or a garden hose for curves.
• Stage blocks close to the work so you’re not lifting farther than needed.
• Keep PPE handy: gloves, eye protection, dust mask for cutting.
• Have caps or pavers on site to finish tops the same day.

Reusing blocks saves money and gives you sturdy, good-looking results. Start small, get a feel for layout and base work, then build bigger pieces with confidence. If you want more depth on unit types and raised bed safety, the NCMA shapes sheet and the raised bed guidance linked above are great quick reads. For fire features, that NFPA primer helps you keep sparks under control while you enjoy the glow.