According to Craftsman National Estimator, "High time difficulty factors for surface preparation and painting. Painting takes longer when heights exceed 8' above the floor. Productivity is lower when an application requires a roller pole or wand on a spray gun or when work is done from a ladder or scaffold. When painting above 8', apply the following factors:
This job is usually done by a professional house painter. The painter will assess the walls, clean, and make any necessary repairs or removal of old wall coverings. They will also tape off any adjacent surfaces and cover nearby furniture and floors with drop cloths. Typically, they will apply a layer of primer, then one to three coats of paint, depending on the color and coverage. Once the paint is dry, they take a final walkthrough to inspect and make any necessary touch ups. Denver House Painting
A thorough scrubbing is a must before painting any exterior surface. It removes the dirt and broken-down paint residues that keep fresh coats from adhering and gets rid of mildew that grows on paint in all but the most arid climates. Most contractors clean with pressure washers, but in the hands of someone unfamiliar with the equipment, these can gouge wood, shatter glass, and drive water behind siding and trim. Using a hose, a pump sprayer, and a scrub brush is slower but safer, and just as effective. Denver Home Painting
Prepping a house costs anywhere from $0.50 to $2.50 per square foot. This is almost always included in the total project price. However, the DIYer might negotiate some discounts for completing this work on their own. Be warned, proper prep is key to the quality and durability of the finish. If you do this work yourself, the contractor might no guarantee to finished product. Home Painters Denver CO
Stripping – $54–$151/100 sq. ft.. “The principle of paint strippers is penetration of the paint film by the molecules of the active ingredient, causing its swelling; this volume increase causes internal strains, which, together with the weakening of the layer's adhesion to the underlying surface, leads to separation of the layer of the paint from the substrate.”— Wikipedia. All the stripper will do is soften the paint. You’ll still have to scrub or scrape it off.