If you're putting aside money for a home renovation, you may need to save up a bit longer than you think. According to a recent survey by Discover Personal Loans, the average costs for several projects are nearly twice what a homeowner expects.

The company surveyed 969 people on Feb. 14, asking respondents how much they thought certain expenses would cost. For the six home improvement projects included in the survey, it based its figures for actual costs on data from the home improvement site HomeAdvisor. In addition to these expenses, Discover Personal Loans asked respondents about perceived costs for starting a business and medical care.

Across all expenses, respondents underestimated actual costs by 34 percent. For home projects, they underestimated the cost by an average of 46 percent.

Respondents' estimates were closest to the actual expense for bathroom remodels, although they still fell 31 percent short. The actual average cost for this work was set at $9,274, while the typical respondent expected that it would cost $6,371.

Estimates for a kitchen remodel were about half of the actual cost. This work carried an average price tag of $19,920, while the average respondent estimated that it would require $10,388.

The average respondent expected that cabinet refacing would only cost $1,766. The actual cost was set at $6,692, or 74 percent higher.

The average estimate for the installation of air conditioning was $3,047, or 42 percent short of the actual average cost of $5,233. The typical respondent expected that the construction of a deck would cost $4,499; the actual cost was 35 percent higher, or $6,919.

Discover Personal Loans said there are several reasons why homeowners might underestimate the cost of a project. The company said a shortage in skilled workers has contributed to higher labor costs recently, while increasing costs of materials can also put a strain on budgets. Homeowners may also decide to expand the scope of their project as it proceeds or need to address problems uncovered during the work.

The survey also found that homeowners were unlikely to regularly save money for home improvements or repairs. Just 37 percent said they were putting money aside each month for this purpose.

Respondents were most likely to say they would rely on a personal loan to fund a roof replacement or a new deck. They were more likely to say they would use credit cards or dip into their home equity to finance new windows or remodeling work for a kitchen or bathroom.