If your existing steel lintel has started to rust, it should be replaced with a pre-stressed stainless steel lintel. This should be done by a competent builder. If you live in a traditionally built home, the new stainless steel lintel must be installed using lime mortar. Using lime mortar prevents moisture from building up inside the brickwork, which causes dampness to appear inside the home. If making repairs to a stone lintel, you can use surface repair mortars to reform an arris or hide erosion. If the stone lintel has failed, it can be replaced using lime mortar. As any builder knows, cracks in masonry can quickly lead to structural problems. One way to prevent further damage is to undertake a process known as crack stitching. This involves installing stainless steel helical bars into the masonry joints, using anchor resin or grout. However, it is important to note that the anchor resin and grouts used are incompatible with porous masonry. As a result, any repairs on this type of material should only be seen as a temporary fix.