industry Home or residential renovation is an almost $300 billion industry in the United States, and a $48 billion industry in Canada. The average cost per project is $3,000 in the United States and $11,000–15,000 in Canada. Professional home improvement is ancient and goes back to the beginning of recorded civilization. One example is Sergius Orata, who in the 1st century B.C. is said by the writer Vitruvius (in his famous book De architectura) to have invented the hypocaust. The hypocaust is an underfloor heating system that was used throughout the Roman Empire in villas of the wealthy. He is said to have become wealthy himself by buying villas at a low price, adding spas and his newly invented hypocaust, and reselling them at higher prices. Renovation contractors Perhaps the most important or visible professionals in the renovation industry are renovation contractors or skilled trades. These are the builders that have specialized credentials, licensing and experience to perform renovation services in specific municipalities. While there is a fairly large ‘grey market’ of unlicensed companies, there are those that have membership in a reputable association and/or are accredited by a professional organization. Homeowners are recommended to perform checks such as verifying license and insurance and checking business references prior to hiring a contractor to work on their house. Because interior renovation will touch the change of the internal structure of the house, ceiling construction, circuit configuration and partition walls, etc., such work related to the structure of the house, of course, also includes renovation of wallpaper posting, furniture settings, lighting, etc. It is worth noting The thing is, the decoration construction team must be approved by the established interior design company to guarantee. Aggregators Aggregators are companies that bundle home improvement service offers and act as intermediary agency between service providers and customers. In popular culture Home improvement was popularized on television in 1979 with the premiere of This Old House starring Bob Vila on PBS. American cable channel HGTV features many do-it-yourself shows, as does sister channel DIY Network. Danny Lipford hosts and produces the nationally syndicated Today's Homeowner with Danny Lipford. Tom Kraeutler and Leslie Segrete co-host the nationally syndicated The Money Pit Home Improvement Radio Show. Movies that poked fun at the difficulties involved include: Mr. Blandings Builds His Dream House (1948), starring Cary Grant and Myrna Loy; George Washington Slept Here (1942), featuring Jack Benny and Ann