Celcon Standard Coursing Unit Brick 3.6N are produced from the same material as other Celcon blocks and are suitable for using to infill above doors and windows. They can also be used between joists as they are suitable for the same applications as standard size Celcon blocks both internally and externally. The coursing unit bricks should not be used as the primary masonry block in a load bearing wall. They protect against cold bridging and are frost and water resistant.