As a real estate agent one, of the questions we are asked all of the time is how to improve or change a home in order to increase its market value and appeal to buyers.
There are a few basic tenets: use neutral colors, make sure the home has curb appeal from the outside and de-clutter the home. However, much of the general advice is subjective. Fortunately, there is an annual study provided by Hanley Wood that adds a quantitative analysis to what can be a subjective process. According to the Remodeling 2010-11 Cost vs. Value Report (costvsvalue.com), only two of the 35 most popular home improvement projects will return more than what was spent on them.
The two projects, based on data and costs for the Los Angeles area, that will return more than what is spent on them for a midrange home are replacing the garage door and replacing the entry door with a steel entry door.
The reason these two are more likely to return more than what is spent on them is because their estimated costs are lower than any other home improvement projects analyzed in the report. 
A new garage door estimated cost is $1,609, and it adds an estimated $1,647 to resale value.
An entry door replacement estimated cost is $1,520, while it adds an estimated $1,701 to the resale value.
Per the report, one of the worst expected returns is a sunroom addition. With an estimated cost of $89,059 and an estimated addition to resale value of $44,360, adding a sunroom is not the way to get a return on your investment.
On a national level, the cost vs. value ratio has been on the decline for the last four years. Between 2006 and 2009, the estimated project costs rose sharply while resale value estimates remained stable.
This year, costs dropped more than 10 percent, returning to pre-2007 levels, but resale values dropped even more – a 15.8 percent slide that is the steepest decline in an eight-year period. However, the Pacific region, which includes our Irvine area, has continued to outperform most of the United States due to the higher resale values.
To read a copy of the entire report, you can go to costvsvalue.com