Renovation quotes can vary by up to 70%, according to a new report commissioned by building advisory service Archicentre, which has recently released a 'cost guide' with typical price ranges for various common renovation projects.

Robert Caulfield, managing director of Archicentre, said the cost guide offers prices on projects from paving, fencing, plastering and tiling, to tree removal, repairs and complete building extensions.

"If homebuyers and renovators have no knowledge of the reasonable costs of building or products, they could be giving a builder or project manager a blank cheque," Caulfield said.

There is an average price range listed in the new cost guide for almost every imaginable home renovation project, Caulfield said, although Archicentre warns that prices will vary according to tradespeople, the quality of the job, materials, site access and other factors.

On average, of the capital cities, Brisbane, Perth and Adelaide offer the least expensive renovation costs, while Sydney, Hobart and Canberra are the priciest, and Melbourne straddles the middle.

The 2008 version of the cost guide shows a slight rise in prices for renovation projects; however, Caulfield said that a potential slowing in the housing market may cause builders to become more competitive in their pricing.

Caulfield added that Archicentre has shown that flexible indoor/outdoor entertainment areas, home offices and home theatres are the most popular renovations and extensions of late, and that there has been an increase in the number of renovators interested in energy-efficient and water-saving designs.