The wall should be adequate to transfer loads, such as from its own weight or the roof it supports, safely to the foundations.
If an opening is formed in a wall, the structure above the opening, even if it is relatively small, will need to be supported. Lintels are normally used to provide such support, in one of two ways:
- One lintel (usually made of steel, with insulation integral to it) that supports both the inner and outer leaf of a cavity wall construction. These usually also serve as a cavity tray which directs moisture from the cavity through the outer skin of the wall construction
- Two lintels (made of steel or concrete), one supporting each leaf of a cavity wall construction. Separate thermal insulation and a cavity tray are likely to be required.
With solid walls it is good practice to use a lintel where insulation can be installed to avoid condensation.
All lintels should have a suitable bearing onto the wall at each side of the opening. It is best to consult with the manufacturer or an engineer for the correct size lintel and bearing.