Domakihub How to Build a Block Wall: Steps, Tips and When to Call a Pro
A practical guide to laying concrete blocks for boundary walls, garden enclosures, and outbuildings in Greece.
Reviewed by Domakihub home & decor pros · 2026-06-23 · 5 min read
A solid block wall adds privacy, security, and long-term value to a home, holiday rental, or hotel in Greece — but the job demands careful groundwork, accurate levelling, and respect for local planning rules. The video above walks through the core masonry sequence from footing to capping, while this article breaks the process into clear stages, flags where permits apply, and tells you honestly when a licensed builder should take over.
What Type of Block Wall Are You Building?
Concrete masonry units (CMUs) — the hollow or solid cement blocks used across Greece for boundary walls, courtyard screens, outbuilding walls, and retaining structures — are cheap, fire-resistant, and durable in the Mediterranean climate. The right choice depends on load: a decorative garden divider up to about 1 m high is a very different project from a 2 m perimeter wall or a structural wall inside a building.
Retaining walls that hold back soil or slope, any wall that forms part of a building's structure, and walls over roughly 1.5 m typically require both a building permit from the local planning authority (Ypiresía Domisías) and a licensed civil engineer to certify the design. Non-structural boundary walls below the municipal threshold are usually permit-free, but always check with your local authority before breaking ground — rules vary by municipality and zone in Greece.
Materials, Tools, and Safety
You will need hollow CMU blocks (typically 20 × 20 × 40 cm in Greece), Portland cement-based mortar (ready-mix bags are easiest for smaller runs), a spirit level, a trowel, a rubber mallet, a masonry string line, and rebar if the wall is taller than one course or load-bearing. For a long or structural wall, a concrete-filled footing with horizontal rebar ties is non-negotiable — the footing depth must sit below frost level and on undisturbed ground.
Wear safety glasses and heavy gloves throughout; freshly mixed mortar is caustic. Keep a bucket of water nearby to wash skin immediately on contact. If you are working near an existing structure, buried utilities, or a slope, have a professional assess the site first to avoid undermining foundations or disturbing drainage.
How to Build a Block Wall: Step by Step
- 1
Dig and Pour the Concrete Footing
Mark the wall line with stakes and string. Excavate a trench at least 40–50 cm deep and roughly twice as wide as your block. Fill with steel-reinforced concrete and allow it to cure for a minimum of 48 hours (longer in cold or wet weather). The footing must be level and square — all alignment errors multiply as courses go up. For walls over 1 m or on sloped ground, a structural engineer should specify footing dimensions and rebar schedule.
- 2
Snap a Chalk Line and Dry-Lay the First Course
Once the footing is cured, snap a chalk line along the centre of the footing to mark the wall face. Dry-lay (no mortar) a full course of blocks to check spacing, confirm how corners will meet, and plan bond pattern — the standard running bond offsets joints by half a block width. Mark any cut positions at this stage and make all cuts with an angle grinder fitted with a diamond masonry blade or a masonry saw.
- 3
Mix Mortar and Lay the First Course
Mix mortar to a smooth, peanut-butter consistency — neither crumbly nor soupy. Spread a 2–3 cm mortar bed on the footing, set corner blocks first, then fill the run between them using a string line pulled taut between the corners as a height guide. Tap each block down with a rubber mallet, check level and plumb constantly, and butter the vertical (head) joints before pressing adjacent blocks together. Scrape off any squeeze-out flush with the face as you go.
- 4
Build Up Courses with Rebar and Ties
Offset each course by half a block (running bond). Every second or third course, insert vertical rebar rods through the hollow cores of the blocks; fill those cores with grout or concrete to lock the rebar in place. For walls in seismic zones — which covers most of mainland Greece and the islands — your engineer may specify closer rebar spacing or pilasters (reinforced block columns) at regular intervals. Keep checking plumb and level with every course; errors do not self-correct.
- 5
Cap the Wall and Allow Curing Time
The top course should be finished with solid cap blocks or poured mortar fill to shed rainwater and seal the hollow cores from moisture and pests. Strike mortar joints to a slightly recessed finish (tooled joint) for weather resistance. Keep the new wall damp for at least three days by misting it with water and covering with hessian or plastic sheeting — slow curing produces a much stronger result, especially in the hot Greek summer. Do not apply render, stucco, or paint for at least 28 days.
Rather have a pro handle it?
Get a vetted renovation pro in your city — one number, booked in EN/EL/DE.
FAQ
- Do I need a building permit to build a block wall in Greece?
- It depends on height, location, and use. Non-structural boundary walls below about 1 m are generally permit-free, but thresholds vary by municipality. Retaining walls, any structural wall, or a wall close to a property boundary or road typically require a permit and a certified engineer. Always confirm with your local Ypiresía Domisías before starting work to avoid demolition orders.
- How thick should a concrete block wall be?
- A single-skin wall using standard 20 cm blocks is adequate for non-load-bearing garden dividers up to roughly 1 m. For taller boundary walls or walls exposed to wind loads in coastal areas, a double-skin or thicker block (30 cm) combined with internal rebar and pilasters is more appropriate. Load-bearing or structural walls must be designed by a licensed civil engineer.
- Can I build a block wall myself or should I hire a mason?
- A short, non-structural garden wall of one or two courses is a realistic DIY project for someone comfortable with manual work and basic tool use. Anything taller than about 1 m, any retaining wall, any wall in a seismic zone, or any wall that is part of a building should be built by a licensed masonry contractor — mistakes in reinforcement or footing depth are costly to fix and can be dangerous. Domakihub can connect you with vetted masons across Greece.