The Thin-Joint System is a fast way of building very accurate, airtight walls. The defining characteristics are the large format of the blocks which are bigger than the average block you will see on site and the mortar used with the blocks to build the walls.
Thin-Joint mortar, called Celfix, is a pre-mixed cement-based product to which water is added on site to make a mortar that sets quickly. It is applied with a special scoop, forming a joint that will be around 2mm thick.
Celfix mortar sets fast - typically reaching stability in 60 minutes – meaning that a 1.5m wall can be built in a day. Once the structural block walls are complete, the roof can be constructed immediately. This creates a waterproof shell allowing the interior trades: electricians, plasterers etc to get started even while the insulation and brickwork is being finished.
This method can considerably reduce time on site and the resulting wall, with very thin mortar joints, will be airtight: increasing the thermal efficiency and helping your home to meet the stringent standards of building performance such as Passivhaus.
You can see how the walls are built in our series of videos.