Boolean operators are specific words used to combine keywords to improve the chances of finding relevant information. The most commonly used Boolean operators are AND, OR and NOT. Search results will contain both of the terms humour and therapy. Using AND decreases the number of results, because each time a keyword is added, the focus of the search is narrowed. Search results will contain one, or both, of the terms humour or laughter or comedy. Using OR increases the number of results, because a broader range of keywords is searched.
The actual cost of a flat roof depends on your location, the materials used, the complexity of the installation, and other factors. 1  Building a flat roof costs approximately $1.50 to $10.00 per square foot. 2  Assuming an average roof size of 1,500 square feet, that s a total cost of $2,250 to $15,000.
Image & Data from HomeAdvisor.com. The national average for roof replacement cost is a little over $6,500, with a range between $2,000 and $12,000 and most homeowners spending between $4,559 and $8,685 according to Home Advisor.This is an enormous range, even for the majority of homeowners.he range of roof replacement cost for this area â including the DC area â is about $2,500 to $11,000 with most homeowners spending between $4,487 and $8,217. These figures represent all roof types and sizes; your roof may cost more or less depending on several different factors.