What are Steel Lintels?
Steel lintels have been used in masonry construction for over 100 years and generally function as a bridge to support the masonry above window and door openings. These are commonly constructed with I-beams, C-channels, angle iron, or tube steel, with an extended plate to support the masonry.
As an important structural component, corrosion of these ferrous metal parts can create significant problems. Damage to other materials due to ferrous metal corrosion is typically referred to as “rust jacking”, the accumulation of corrosion scale.
Corrosion of ferrous metals is the reversion of the metal from its unnatural refined state to its natural ore, e.g., iron oxide, caused by the presence of oxygen and water. Restricting the access of water to these ferrous metals prevents this corrosion.
Sadly, for many years it was common practice to install sealant/caulking between the steel lintels and masonry above. This practice resulted in moisture trapped behind the sealant, resting on the steel, and damaging the structure.
It is not uncommon for significant corrosion to result in section loss, affecting the structural integrity of these components. In the case of steel lintels, rust jacking will most likely have caused shifting of the adjacent masonry, creating cracks that allow even more water at the structural steel.
Correcting the Issue
The repair and/or replacement of steel lintels is costly and usually involves the removal of sufficient masonry to expose the corroded steel. If the corrosion has not caused significant section loss, the steel is cleaned and coated with a rust-inhibiting coating. It is good practice to then install a thru-wall flashing, to direct the water away from the steel, prior to reinstalling the masonry.
If section loss is significant, the lintel is removed and replaced with one of like kind, or better yet, a galvanized or stainless-steel unit, of similar size, prior to installing the thru-wall flashing and masonry units.
The best practice is to prevent moisture from getting at these by keeping the masonry façade watertight. Performing regular façade inspections, looking for open mortar joints, sealant joints, and cracked masonry units is good cost prevention and can pay dividends in the future.