There is no one-size-fits-all answer to this question, as the need for sheathing under metal siding will vary depending on the type of metal siding, the climate, and other factors. Generally speaking, however, sheathing may be needed in order to provide a solid surface for attaching metal siding and to help keep the building weathertight. Consult with a professional contractor to see if sheathing is necessary in your specific case.

Sheathing is not always necessary with metal siding, but it depends on the type of metal siding you are using and the installation instructions. In most cases, sheathing is not needed because metal siding is installed over solid substrate, such as plywood or OSB. However, if you are using a type of metal siding that requires furring strips or a ventilated air space between the metal and the substrate, then sheathing may be required. Be sure to check the installation instructions for your specific type of metal siding to make sure.