So, you're seriously thinking about tackling a fully cinder block shed how to project? Good choice... maybe. Look, building a shed entirely out of concrete blocks isn't the same as slapping together some wood panels on a Saturday afternoon. It's tougher, heavier, and demands more upfront planning. But man, when it's done? You've got yourself a fortress. Seriously, a fully cinder block shed laughs at storms, shrugs off pests, and basically outlives us all. That's the dream, right? A shed you never have to replace.
I built mine back in 2019 after a nasty storm turned my old wooden shed into kindling. Never again. This guide isn't just theory – it's packed with the dirt-under-the-nails reality of actually doing the how to build a fully cinder block shed job. I'll cover the good, the bad, where you absolutely cannot cut corners, and crucially, how much this beast might actually cost you (spoiler: it costs more than wood, but let's talk value).
Why You Might Seriously Want a Cinder Block Shed:
- Indestructible: Wind? Fire? Termites? Moisture rot? Forget it. Blocks don't care. This shed becomes a permanent fixture.
- Low Maintenance: Paint it once (if you even want to), then ignore it for decades. No warping, no rotting boards to replace.
- Security: Good luck to anyone trying to break in. Those walls are tough. Way better than thin wood for storing anything valuable or dangerous.
- Temperature Stability: Blocks have thermal mass. It stays cooler in summer and holds a bit of heat better in winter than a thin wood shed. Not insulated, mind you, but better.
- Fire Resistance: Major peace of mind if you're storing fuels, paints, or equipment.
The Not-So-Fun Realities:
- Cost: Blocks, mortar, rebar, concrete for the footing... it adds up fast. Easily 1.5x - 2x the material cost of a comparable wood shed upfront.
- Labor Intensive: This is heavy, physical work. Mixing mortar, laying blocks perfectly level and plumb, bending rebar... it's not a quick weekend gig. My back felt it for days.
- Foundation is CRITICAL: Mess this up, and your whole shed cracks and fails. No shortcuts here. Deep footings below frost line are non-negotiable.
- Permanence: Once it's built, moving it isn't an option. Be darn sure about location and size.
- Skill Level: While simpler than building a house, laying a straight, plumb block wall takes practice. First-timers will be slow and might need help.
Still with me? Okay, good. Let's get into the actual fully cinder block shed construction process. This is the real meat of how to actually make it happen.
Building Your Fully Cinder Block Shed: Step-by-Step Breakdown
Think of this as the blueprint. It's the order you NEED to follow. Jumping ahead leads to expensive tears.
Pre-Work: The Stuff You Absolutely Cannot Skip
Seriously, do not skip this. Getting permits wrong or building in the wrong spot costs way more time and money than doing it right upfront.
- Check Zoning & Permits: Call your local building department. Every area has rules about shed size, location (how far from property lines, your house), foundation depth, and whether a fully cinder block structure even counts as an "accessory building" or needs different permits. Don't assume. Fines or forced demolition suck.
- Pick Your Spot Wisely:
- Drainage: Water MUST flow away from the shed. A soggy foundation is a cracked foundation.
- Access: How will you get blocks, mortar, sand, and your roof materials to the site? Wheelbarrow path? Clear it.
- Sun & Shade: Think about how you'll use it. Do you want morning sun? Afternoon shade?
- Underground Utilities: Call 811 (USA) or your local "call before you dig" service! Hitting a gas line is catastrophic.
- Design & Dimensions:
- Sketch It: Simple drawing with dimensions. Decide on door size and placement (standard 36" wide door is common).
- Block Math: Standard cinder blocks are 8" high x 16" long. Factor in the mortar joints (about 3/8") when calculating wall lengths and heights. Want an 8ft wall? Each course (layer) is ~8.375" high with mortar. So roughly 11.5 courses (round up to 12). Adjust your height based on this.
- Roof Type: Gable (peaked) or shed-style (slanted)? Affects complexity and materials.
The Foundation: Where Your Fully Cinder Block Shed Lives or Dies
This is the bedrock (literally and figuratively). Skimp here, and your entire shed crumbles. I learned this the hard way on a garden wall years ago. Frost heave is relentless.
Step 1: Excavation & Footings
- Dig Deep: Footings must extend below your local frost line. This varies wildly (check codes!). In Minnesota, it might be 60 inches! In Georgia, maybe 12 inches. Know YOUR number. Footing trenches should be wider than your planned block wall thickness (e.g., 16-18 inches wide for a standard 8" wide block wall).
- Level & Square: Use batter boards and string lines to outline the exact perimeter. Check diagonals – they must be equal for a square layout. Laser levels are godsends here. Double, triple-check.
- Reinforce: Place rebar cages within the trench. Typically, two continuous lengths of #4 rebar running lengthwise in the bottom of the trench, tied to vertical 'dowels' that will stick up into the block walls. This ties the footing to the walls.
- Pour Concrete: Use a minimum 3000 PSI concrete mix. Fill the trenches to just below grade level. Smooth the top. Let it cure properly (usually 3-7 days minimum, follow mix instructions). Keep it damp for the first few days for maximum strength.
Step 2: Laying the Block Courses
This is the main event. Patience and precision win here. Don't rush.
- Gather Tools:
- Masonry trowel
- Level (4ft and 2ft)
- Mason's line & line blocks
- Jointer tool
- Brick hammer (for scoring/cutting blocks)
- Mortar mixing tub or mixer (renting a mixer is worth it for more than ~100 blocks!)
- Wheelbarrow
- Mortar hoe
- Safety glasses, gloves, knee pads (trust me!)
- Mortar Mix: Type S mortar is standard for above-grade work like this. Mix ratio is roughly 1 part Portland cement, 1/2 part hydrated lime, 4.5 parts damp masonry sand. Add water slowly until it's the consistency of thick peanut butter – it should hold its shape when troweled but still be workable. Mix small batches (enough for 30-45 mins work). Mortar sets fast.
- Laying the First Course (This is Critical!):
- Snap chalk lines on the footing corresponding to the outside edges of your block walls.
- Spread a 1-inch thick bed of mortar INSIDE the chalk lines.
- Set the corner blocks FIRST. Use the level to make sure each corner block is perfectly level AND plumb (vertical) in both directions. This sets the stage for the whole wall. Adjust immediately if needed.
- Stretch a mason's line between the corner blocks at block height. This is your guide for the top edge of the first course.
- Butter the ends of each block with mortar (called "buttering the head joint"). Set each block firmly against the line, tapping down gently with the trowel handle to set it into the mortar bed and achieve the right height. Check level frequently as you go along the wall.
- Check for plumb every few blocks. Adjustments are easier now than later.
- Keep mortar joints consistent (about 3/8").
- Fill the hollow cores of every block in the first course completely with mortar. This creates a solid base.
- Building Up:
- After the first course, start setting corner blocks for the second course, overlapping the blocks below (staggering the joints).
- Run lines between corners for each course.
- Apply mortar to the top flange of the block course below ("bed joint") and butter the head joints.
- Set blocks, tapping down to the line.
- Constantly check level and plumb.
- Vertical Rebar: Every 24-36 inches (check code!), and definitely at corners and beside door openings, insert vertical rebar (#4 or #5) down into the hollow cores. Fill the core surrounding the rebar completely with concrete or mortar mix. This is essential seismic and structural reinforcement. Don't skip this!
- Lintels Over Openings: For the door (and any windows), you need a lintel. Concrete lintels are common. They sit on the blocks beside the opening and span the gap. You MUST have solid bearing (at least 8 inches) on each side. Set it carefully on mortar.
- Tooling Joints: Once the mortar starts to firm up (thumbprint hard), use your jointer tool to compress and shape the joints. This makes them weather-tight and looks professional.
| Material | Quantity | Purpose | Approx. Cost Range | Notes |
|---|---|---|---|---|
| Standard 8x8x16 Cinder Block | 350-400 blocks | Wall Construction | $1.50 - $3.00 per block | Buy 10% extra for cuts/waste. Check for chips/cracks. |
| Type S Mortar Mix (60lb bags) | 35-45 bags | Laying blocks & filling cores | $6 - $10 per bag | Depends on mix, sand used, etc. |
| Concrete (3000 PSI for Footings) | 1.5 - 2 cubic yards | Footings | $125 - $150 per yard + delivery | Based on 12" deep x 16" wide footings. |
| #4 or #5 Rebar (60ft sticks) | 8-10 sticks (Footing & Vertical) | Reinforcement | $6 - $10 per 20ft section | Cut to length. Need ties. |
| Concrete Lintel (8ft) | 1 (for door) | Door Header | $50 - $100 | Must be rated for load. |
| Roofing Materials (Trusses, Sheathing, Shingles) | Varies | Roof | $800 - $2000+ | Depends on material choice (Asphalt, Metal). |
| Exterior Door (Prehung Steel) | 1 | Entry | $150 - $400 | Steel is durable & secure. |
| Misc. (Anchors, Fasteners, Caulk, Tools) | N/A | Various | $200 - $500 | Rental costs for mixer, etc. |
Costs are estimates and vary SIGNIFICANTLY by location, supplier, inflation, and specific choices. DIY labor not included.
Step 3: The Bond Beam - Locking it All Together
Almost done with the walls! The top course gets special treatment.
- Use bond beam blocks. These look like regular blocks but have a deep channel along the top instead of solid webs across.
- Lay this final course.
- Place two continuous lengths of #4 rebar inside the channel along ALL walls.
- Fill the entire channel with concrete mix. Trowel smooth.
- This bond beam is crucial. It ties all the walls together rigidly and provides a solid, level surface to anchor the roof structure. Don't skip this step!
Step 4: Roofing Your Fortress
Now you have four sturdy walls and a solid top. Time to put a lid on it.
- Anchoring: You need to securely anchor wooden sill plates (pressure-treated 2x lumber) to the top of the bond beam. Use anchor bolts (J-bolts or wedge anchors) embedded in the wet concrete of the bond beam OR drill and epoxy them in later. Space them every 4-6 feet and near corners/ends.
- Roof Structure:
- Option 1: Build Trusses. Pre-made wood trusses are common and relatively easy to install with helpers. Lift into place, attach securely to the sill plates.
- Option 2: Build Rafters. More traditional cut roof. Requires more skill but offers attic space potential. Need ridge board, rafters cut to pitch, collar ties.
- Sheathing: Cover trusses/rafters with plywood or OSB roof sheathing.
- Underlayment: Install roofing felt or synthetic underlayment over the sheathing.
- Roofing Material: Install your chosen roofing – asphalt shingles, metal panels, etc. Follow manufacturer instructions precisely for overlaps, fasteners, flashing.
- Flashing: Critical! Where the roof meets the block walls, you MUST install step flashing and counter-flashing integrated into the mortar joints OR a continuous metal kick-out flashing sealed properly. This prevents water from running behind the walls.
Step 5: Door(s) and Finishing Touches
- Hang the Door: A pre-hung exterior steel door is the simplest solution. Set it plumb and level in the rough opening you left in the wall, shimming carefully. Secure through the frame into the block using masonry anchors (like Tapcon screws). Caulk generously around the exterior trim.
- Interior (Optional):
- Floor: Most leave a concrete slab or compacted gravel floor. You could pour a slab inside later if desired.
- Wiring: Plan conduit runs BEFORE pouring footings/walls for power! Much harder later. Or use exterior-rated conduit.
- Shelving: Attach shelves directly to the block walls using masonry anchors and brackets.
- Exterior Sealing: While block is durable, sealing the exterior with a quality masonry sealer can reduce water absorption and efflorescence (that white powdery residue). Not strictly necessary, but can help longevity/appearance.
Important Reality Check: Building a fully cinder block shed is a significant investment in time, money, and sweat. Be realistic about your skills, budget, and timeline. Rushing leads to mistakes that are hard or impossible to fix later. Hiring a mason for the blockwork is a smart option if you're unsure.
Fully Cinder Block Shed Costs: DIY vs. Pro (What You Need to Budget)
Let's talk money because this is where sticker shock often happens. Forget vague estimates. Here's a breakdown based on my experience and current material trends for a solid fully cinder block shed how to build.
| Cost Category | DIY (Materials Only) | Hiring a Mason (Materials & Labor) | Notes |
|---|---|---|---|
| Foundation (Concrete, Rebar, Forms) | $600 - $900 | $1,500 - $2,500 | Excavation costs extra if you hire it out. |
| Cinder Blocks & Mortar | $800 - $1,400 | $2,000 - $3,500+ | Biggest material cost. Labor is intensive. |
| Rebar & Bond Beam Concrete | $200 - $350 | $500 - $800 | Essential for strength. |
| Roof Structure (Trusses, Sheathing, Shingles) | $800 - $2,000 | $1,500 - $3,000 | Highly variable based on materials. |
| Door & Frame (Steel Prehung) | $150 - $400 | $150 - $400 | Usually same cost DIY/Pro. |
| Fasteners, Anchors, Flashing, Caulk, Sealer | $200 - $500 | $300 - $600 | Easy to underestimate. |
| Masonry Tools (Buy/Rent) | $100 - $300 | Included in Labor | Trowels, levels, mixer rental. |
| TOTAL ESTIMATE RANGE | $2,650 - $5,850 | $6,000 - $10,800+ | Significant variability! |
Why the huge ranges? Location (cost of materials/labor varies wildly), exact size, block quality (standard vs. premium), roofing choices (basic shingles vs. metal), foundation depth/complexity, door quality, and whether you need permits/inspections factored in. DIY saves labor but takes significant time and requires skill.
My take? The material cost for my 10x12 was about $4100 back in 2019 (blocks were cheaper then!). I spent 10 full weekends and evenings doing it myself with one helper on heavy lifting days. Hiring it out would have easily doubled the cost. Ask yourself: Is the time/effort worth the savings? Or is paying a pro for the core blockwork smarter?
Fully Cinder Block Shed: Your Questions Answered (The Real Ones)
Let's tackle the common questions that pop up when people search for fully cinder block shed how to information:
Can I build a fully cinder block shed alone?
Honestly? It's possible, especially for a small shed, but it's brutally hard and slow. Lifting blocks constantly, mixing mortar, holding blocks while you level... it's a two-person job minimum for efficiency and sanity. Larger sheds absolutely need help. Pay in pizza and beer if needed!
Do I need to insulate a cinder block shed?
Blocks alone aren't insulated. If you plan to heat it or work in it year-round in extreme climates, yes, insulation is smart (and usually requires building interior stud walls). For just storage? Probably not necessary. Insulation adds significant cost and complexity. Remember, a fully cinder block shed construction is primarily about durability, not inherent climate control.
How thick do the walls need to be?
For a single-story shed up to about 10-12 ft high, a single-wythe (one block thick) wall using standard 8-inch wide blocks is usually sufficient, IF properly reinforced with rebar in cores and bond beam. Double-check local codes though. Taller or larger structures might need thicker walls.
What's the difference between cinder blocks and concrete blocks?
Technically, "cinder blocks" used to be made with coal cinders (lighter/weaker). Modern "concrete blocks" or "CMUs" (Concrete Masonry Units) are made with sand and gravel aggregates. They are stronger and denser. For a shed, use standard concrete blocks. They are often still colloquially called "cinder blocks," but the stronger type is what you want for a fully cinder block shed.
Can I add windows?
Absolutely! You need to frame the rough opening with solid blocks or pilasters beside it and install a concrete lintel above the window, just like over the door. Use pre-made window bucks or flash carefully. Vinyl windows designed for masonry are common. Plan the placement when you lay the courses.
How long does it take to build one?
This is the "how long is a piece of string?" question. For two reasonably fit novices working weekends:
- Site Prep & Foundation: 1-2 weekends
- Block Laying (Walls & Bond Beam): 3-5 weekends (This is the slog)
- Roofing: 1-2 weekends
- Door & Finishing: 1 weekend
Is a concrete slab floor necessary?
No. Many block sheds have compacted gravel floors or just the natural ground (if very dry). A poured concrete slab is nicer for durability, levelness, and keeping dust down, but it's an extra cost and step. You can pour it later inside the finished shed if you leave enough headroom. Consider drainage if you skip the slab – water shouldn't pool inside.
Will a fully cinder block shed increase my property value?
Maybe, but don't count on a huge ROI dollar-for-dollar like a kitchen reno. What it definitely does is add significant durability and utility that lasts decades. It signals quality construction to potential buyers. A well-built, attractive block shed is an asset, unlike a rotting wooden one that's a liability.
The Final Word: Is a Fully Cinder Block Shed Right For YOU?
Building a fully cinder block shed isn't the easy path. It demands more upfront investment – both cash and sweat – than wood. But let's be real: What's the true cost of replacing a flimsy shed every 10-15 years? The constant maintenance? The worry during storms?
If you need a shed that's truly permanent, incredibly secure, fire-resistant, and virtually maintenance-free for the next 50 years, then yes, going fully cinder block is a fantastic solution. It's a legacy building. That feeling of solidity when you close the door? Priceless.
If you're handy, patient, have a helper (or can hire the blockwork), and want a forever solution, I say go for it. Follow the steps, respect the foundation, reinforce properly, and take your time. That shed isn't going anywhere.
If your budget is tight, your timeline is short, or you aren't confident in your masonry skills (or back strength!), a quality wooden shed or even a metal building kit might be a more practical choice right now. There's no shame in that.
Hopefully, this guide cuts through the fluff and gives you the raw, practical info you need to decide if tackling a fully cinder block shed how to project is your next big adventure. Measure twice, pour once, and build something solid!