New guidelines advise that previous practices of building timber joists directly into the brickwork of a building are no longer advisable at the shrinkage that occurs in both the timber and the mortar can allow air to leak into the cavity. Joist hangers are an alternative solution however they difficult to fit and cumbersome and can lead to squeaky, springy floors. Minera Roof Trusses Joist Seals are excellent at securing your floor joists to the structure of your build with no air leakage.