If there is any peeling — and there usually is somewhere — it's essential to scrape off any loose paint. This doesn't just mean the parts that are already separated from the wood and ready to fall off on their own. Each spot where paint has peeled loose needs to be scraped thoroughly until you can no longer get the sharp corner of a putty knife under any of the surrounding edges of paint. Then, the bare spot needs to be sanded until the paint edges are smooth.
The cost to paint metal siding -- most commonly aluminum and galvanized steel -- will depend on a variety of factors. In some instances, a simple cleaning will suffice to prepare metal siding for painting. In worst cases, painting professionals will need to repair metal that is rusted, damaged or missing pieces due to climate conditions. In the case of severe damage, a professional will have to remove the old finish and paint to get to the original layer, which will add on to the final price. When you add the actual painting of the metal siding, you might be looking at a final bill between $400 (~250 sq. ft.) and $1,500 (~1,000 sq. ft.).
The cost to paint the exterior of your home will vary depending on the size of your home, the condition of your siding, type of paint used and other factors. The average cost for labor and supplies ranges between $1,800-$3,800 and it may cost $6,500 or more for a large, custom project. In addition, you may need to pay more if there is damage to your siding or other challenging aspects of your job.