Brick and Masonry

Brick, lightweight aggregate block and AAC · Bond patterns · mortar, material selection and practical estimating

Brick, lightweight aggregate block (Leca) and AAC are commonly used in facades, garages, internal walls, garden walls and other masonry applications. Load-bearing masonry, retaining walls and other structurally significant work must always be assessed separately.

Brick formats and block sizes

Norwegian normal format (NF brick)

• Brick dimensions (without joint): 228 × 108 × 54 mm (length × width × height)
• Coordinating dimensions (with 10 mm joint): 238 × 118 × 64 mm
• Approx. 65 pcs/m² in running bond (see calculation below)
• Weight: typically 2.4–2.8 kg per brick (kiln-fired facing brick varies)

Common European brick formats

• 250 × 120 × 65 mm — a common European brick format; actual dimensions vary by market and manufacturer
• With 10 mm joints: 260 × 130 × 75 mm coordinating dimensions
• Approx. 51 pcs/m² in running bond

Lightweight aggregate block (for example Leca)

• Typical block format: around 490 × 190 × 190 mm — common sizes vary between systems and manufacturers
• Lighter interior block: smaller formats are also used for some non-load-bearing and lighter wall applications, depending on the system and manufacturer
• Approx. 10 pcs/m² for the 490 block, 12–13 pcs/m² for the 390 block
• Lower weight than brick (approx. 11.0–16.0 kg each), good sound insulation and fire resistance

AAC / aerated concrete (Ytong/Hebel/Siporex)

• Autoclaved aerated concrete — air pockets give excellent insulation and low weight
• Standard: 600 × 200 mm footprint, heights from 75 to 250 mm
• Typically around 8–9 pcs/m² for units with a 600 × 200 mm face; the per-m² count depends only on the face size, while the block thickness (commonly from ~75 up to ~400 mm) is chosen by wall type and structural/thermal requirements — so always quote AAC as length × height × thickness
• Lambda value (thermal conductivity) varies by density and product, but AAC normally provides better thermal insulation than brick and lightweight aggregate block

Bond patterns

The bond pattern determines how bricks are laid in relation to each other. Bond choice affects both appearance and load distribution, and continuous vertical joints will normally weaken the masonry unless the solution is specifically designed or reinforced.

Running bond (stretcher bond)

The most common pattern. Each course is offset by half a brick length (114 mm for NF brick). All bricks are laid with the long face showing (stretchers). Provides good strength in the longitudinal direction of the wall. Used for facades, garden walls and boundary walls.

English bond (cross bond)

Alternate courses are stretcher courses and header courses (bricks laid with the short end showing). The header courses tie the wall together across its width, providing very high strength. Used for load-bearing walls and structures requiring a thicker wall.

Stack bond

Bricks are stacked directly above one another — vertical joints are continuous. Structurally weak without reinforcement (mesh in the joints), but used decoratively and for non-load-bearing interior partition walls. Always requires sign-off from a structural engineer for load-bearing use.

Mortar

Mix ratios

• Interior masonry: use the mortar type and strength class recommended for the masonry unit system and exposure conditions; ready-mixed mortar is often the safest choice for small jobs
• Exterior masonry and plinth: use mortar documented as suitable for exterior exposure, frost and the relevant unit type
• Exposed facing brick in harsh conditions: always follow the brick and mortar manufacturer's recommendations for mortar type, exposure class and joint detailing
• Cold weather: do not lay masonry on a frozen base or let fresh mortar freeze before it sets — protect the work and follow the mortar manufacturer's minimum-temperature and cold-weather guidance rather than a single universal figure
• Pre-mixed bagged mortar (25 kg bags) is the simplest option for DIY work and gives consistent quality

Joint thickness and consumption

• Standard joint thickness: 10 mm (horizontal and perpend joints) for NF brick and EU format
• Ytong/Siporex: thin bed adhesive 2–3 mm — specialist adhesive, not ordinary mortar
• Mortar consumption for brick in running bond: approx. 0.025 m³ per m² of wall face (≈ 25 litres per m²), but actual consumption varies with brick format, joint thickness, waste and workmanship
• 1 bag ready-mix mortar (25 kg) typically yields around 0.013 m³ fresh mortar, but always check the product data sheet for the actual yield

Calculating bricks and mortar

Bricks per m² (running bond)

These figures are for a single leaf of facing brick (one brick / half-brick thick) laid in running bond. A solid one-brick wall, or a double-leaf / cavity wall with two leaves, needs proportionally more brick. The base formula for bricks per m² is:

• NF brick: 1 ÷ ((0.228 + 0.010) × (0.054 + 0.010)) = 1 ÷ (0.238 × 0.064) = 1 ÷ 0.015232 ≈ 65.6 pcs/m²
• EU EN771: 1 ÷ ((0.250 + 0.010) × (0.065 + 0.010)) = 1 ÷ (0.260 × 0.075) ≈ 51.3 pcs/m²
• Add 5–8% for waste and cuts (8% for many openings, 5% for long straight runs)

Total material requirements — example

Garage wall 4.0 m long, 2.4 m high, one 2.0 × 2.0 m door opening (4 m² opening). Running bond with NF brick:

• Net wall area: (4 × 2.4) − 4 = 9.6 − 4.0 = 5.6 m²
• Bricks: 5.6 × 65.6 × 1.07 (7% waste) ≈ 393 pcs → round up to 400 pcs
• Mortar: 5.6 × 0.025 = 0.14 m³ fresh mortar ≈ 11 bags ready-mix (25 kg)

External masonry — moisture and movement detailing

Quantities are the easy part; on an external wall the detailing is what keeps water out and stops cracking. The exact rules and components vary by country and by wall type (cavity, rendered single-leaf, brick veneer), so treat the following as items to design in with your system supplier and local code — not optional extras:

• Damp-proof course (DPC) / cavity trays: a continuous barrier near the base and over openings to stop rising and penetrating damp, lapped and stepped correctly.
• Wall ties: in a cavity or veneer wall the outer leaf must be tied back to the structure with corrosion-resistant ties at the required spacing — with extra ties around openings and at edges.
• Weep holes and a drained/ventilated cavity: open weeps above trays and at the base so any water in the cavity drains out — never bridge or fill the cavity with mortar droppings.
• Movement joints: masonry expands, shrinks and moves; vertical (and where needed horizontal) movement joints at the spacing for the unit type prevent random cracking.
• Lintels and support: openings need a correctly sized lintel with its own DPC/cavity tray and adequate end bearing.

Regulations and structural design

Local regulations and permit requirements

• Local regulations set requirements for structural safety, moisture resistance and workmanship — check with your local authority what applies to your project.
• Permit requirements depend on the type of work, location, size and local planning conditions, and should be checked with the municipality where there is any doubt
• Load-bearing masonry, retaining walls, facade changes and other structurally significant work should always be assessed by a qualified professional before construction
• For frost-exposed and exterior masonry, the units, mortar and detailing must be documented as suitable for the relevant exposure conditions

Structural design

• Masonry structures require structural design by a qualified professional for load-bearing walls — in Europe to Eurocode 6 (EN 1996), and elsewhere to the equivalent local code (e.g. TMS 402 in the US).
• Product requirements and specifications are linked to manufacturer documentation; actual solutions must be designed or selected from documented systems
• Avoid presenting load-bearing solutions or mortar classes as universal rules unless they are tied to structural design, exposure class and manufacturer documentation

Reference table

Common mistakes

• ✗Mortar beds too thick — joint thickness over 12 mm reduces load capacity and looks poor
• ✗Laying in rain or frost — mortar will not cure below +5 °C and is washed out by rain, leaving poorly bonded joints
• ✗No damp-proof course under the first course — capillary rise causes salt efflorescence and frost spalling
• ✗No movement joints on long runs (over 6–8 m) — thermal movement cracks the masonry
• ✗Mortar too thin — runs out of the joints and stains the face of the bricks; use the correct consistency for the joint type
• ✗No bond pattern (all vertical joints aligned) — reduces load capacity and is generally not permitted in structural masonry
• ✗Building too many courses per day — fresh mortar can support only 1–1.5 m of fresh masonry before the wall tips or settles unevenly

Calculate your materials

Use the brick calculator for automatic calculation of bricks and mortar: