Thermal Bridging: Which Blocks are Best?
Thermal bridging occurs where there are breaks in the insulation in the fabric of a building and can account for up to 35% of a building’s total heat loss. Architects and designers often specify aircrete blocks, such as Quinn Lite thermal blocks, to effectively combat this heat loss. Quinn Lite blocks can reduce heat loss through thermal bridging by up to 80%, so it’s a very effective way of improving the overall performance of a house.
But, can Quinn Lite blocks be replaced with an alternative block, such as a lightweight aggregate block? The blocks are very different, so it is not just a matter of switching one block for another. There will certainly be performance issues and potentially compliance issues also.
Thermal Blocks Comparison
We can see this very clearly when we look at one very common junction, the floor to wall junction as shown in Fig. 1, and compare using Quinn Lite bocks with using lightweight aggregate blocks.
To compare, we will look at three key consideration: cost, performance and compliance.
To effectively combat thermal bridging, this detail will require four lightweight aggregate blocks, whereas, when using Quinn Lite blocks, only one block is required as shown in Fig. 2.
Cost and performance
Comparing the cost, lightweight aggregate blocks will cost around 4 times more in this detail, whereas just one Quinn Lite block is not only much cheaper, but is also 15% more thermally efficient than the four lightweight aggregate blocks.
Blocks are located below DPC in this junction. For Quinn Lite blocks, this is no problem as they have declared thermal performance for use both above and below DPC. Other blocks, including lightweight aggregate blocks, do not have declared performance below DPC.
In addition, there are important compliance considerations when using blocks in this location. Lightweight aggregate blocks do not meet the compliance requirements of NSAI publication SR325 for durability.
Quinn Lite blocks, however, have been tested and are third party agrément certified as freeze thaw resistant, which makes them ideal for use in this location.
The comparison is clear. To combat thermal bridging, Quinn Lite is the best block available in Ireland, and the only thermal block certified for use in this location, below DPC.