How to Estimate the Cost for a Patio Enclosure. Enclosures can range from a cozy retreat to a summer party venue. A patio enclosure costs an average of $11,000, with the low end at $3,000 and the high end at $20,000, according to HomeAdvisor.com.At the extremes, a basic roof-plus-screening job can cost about $500 while a fully tricked-out sunroom averages $73,000.Considering the range of options available, you'll need some fairly firm ideas of what you want in a patio enclosure to estimate the cost.allet Busters. The biggest cost of a more elaborate enclosure, such as a sunroom, is the windows. A sunroom is typically defined as having at least 40 percent of its walls made of glass. Window prices vary. A lot. For example, a 2-foot-by-3-foot window can cost between $60 to $260 each at a home-improvement store.