Slightly off topic here, but the galvanized lintels such as IG are not the be-all-and-end-all.
Builders think that because they're galvanised, they can be installed without any protective covering such as a cavity tray.
Not so.
Initially, they are OK, but over time, the cement mortar around them gradually turns from alkaline to slightly acidic in the presence of damp (which can be
through rain penetration or even condensation). The acid then attacks the zinc, and exposes the steel. When the steel oxidizes, it expands and fractures the mortar joints around it.
Builders think that because they're galvanised, they can be installed without any protective covering such as a cavity tray.
Not so.
Initially, they are OK, but over time, the cement mortar around them gradually turns from alkaline to slightly acidic in the presence of damp (which can be
through rain penetration or even condensation). The acid then attacks the zinc, and exposes the steel. When the steel oxidizes, it expands and fractures the mortar joints around it.