Planning note: Actual recommendations depend on the substrate, existing coatings, moisture, exposure and intended use.
Adhesion
Paint cannot bond reliably to dirt, grease, loose coatings or glossy surfaces that require deglossing.
Appearance
Patches, ridges and damaged substrate remain visible beneath paint unless they are repaired and sanded appropriately.
Durability
Primers and sealers address stains, porosity, bare areas and difficult substrates so finish coats perform as intended.
When to request an estimate
An on-site conversation is useful when surfaces are peeling, stained, damaged, difficult to access or part of a larger renovation. A written scope can identify preparation and product assumptions before work begins.