{"product_id":"wienerberger-k209-blue-perforated-class-b-73mm-engineering-brick-pack-of-368","title":"Wienerberger K209 Blue Perforated Class B 73mm Engineering Brick Pack of 368","description":"\u003ch3\u003eWienerberger K209 Blue Perforated Class B 73 mm Engineering Brick\u003c\/h3\u003e\n\nThis brick is a perforated, extruded wirecut engineering unit designed for strength, moisture resistance, and structural use rather than appearance. Engineering bricks are classified by performance, not visual quality. Because clay and manufacturing can vary, mixing units from multiple packs is prudent to minimise tone variation.\n\n\u003ch3\u003eKey Specifications\u003c\/h3\u003e\n\nSize: 215mm × 102.5mm × 73mm\nColour: Blue\nTexture: Smooth, Perforated Wirecut\nWater Absorption: ≤ 7%\nDurability: F2\nCompressive Strength: ≥ 75 N\/mm²\nPack Quantity: 368\nActive Soluble Salts: S2\nThermal Conductivity: 0.840 W\/(m·K)\nReaction to Fire: Class A1\nGross Dry Density: 1800 kg\/m³\nSize Tolerance: T2\nRange Tolerance: R1\n\n\u003ch3\u003eDescription \u0026amp; Usage Notes\u003c\/h3\u003e The **K209 Blue Class B** perforated engineering brick is engineered for high-load and moisture-critical environments such as foundations, retaining structures, or damp-proof courses. With a strong compressive strength of ≥ 75 N\/mm² and a low water absorption rating (≤ 7%), it performs reliably under demanding conditions. The F2 frost-resistance rating further supports its use in exposed applications.\n\nBecause this is an engineering brick, surface appearance (colour, texture uniformity) is not the primary focus. For aesthetic facades, use a facing brick. Mix bricks from different packs to reduce visible variation. Use proper detailing—cavity design, flashing, drainage, mortar compatibility—to ensure longevity.\n\n\u003ch3\u003eFAQs\u003c\/h3\u003e \u003ch4\u003eIs 7% water absorption acceptable for engineering bricks?\u003c\/h4\u003e Yes — for Class B engineering bricks, ≤ 7% absorption is standard and helps ensure durability in load-bearing and moisture-prone applications. \u003ch4\u003eWhat does the F2 durability rating mean?\u003c\/h4\u003e It means the brick is frost-resistant and suitable for general UK external exposure. In extremely harsh or marine environments, higher durability classes or protective design may be advisable. \u003ch4\u003eCan this engineering brick be used as a facing brick?\u003c\/h4\u003e It’s technically possible but not recommended. Engineering bricks aren’t manufactured for consistent visual quality, so for visible facades, a designated facing brick is usually a better choice.","brand":"JJ Building Materials","offers":[{"title":"Default Title","offer_id":54801329848662,"sku":"161977","price":545.85,"currency_code":"GBP","in_stock":true}],"url":"https:\/\/jjbuildingmaterials.co.uk\/products\/wienerberger-k209-blue-perforated-class-b-73mm-engineering-brick-pack-of-368","provider":"JJ Building Materials","version":"1.0","type":"link"}