Think about all that work in the field, to apply exterior casing in the field. From a simple flat casing picture framed detail to the casing with a crown detail and keystones with a historic sill. It’s costly for materials, labor, and finishing.
Now, what if all that time that was spent on obtaining lengths of material, designing, cutting, assembling, and touching up was replaced with a custom, no finished painting required surround that fits perfectly around the window? Furthermore, when considering your materials and labor, if it was a cost saving why wouldn’t you?
Window surrounds are a great way to save time and money on a project while giving you a factory-made quality that cannot be easily replicated in the field.