7 On Your Side: Consumer Reports on how to avoid renovation mistakes

Consumer spending is projected to reach $155 billion this year. Consumer Reports has some ideas on how to avoid the biggest renovation mistakes.

Consumer Reports says planning is essential.

Sally Loizeaux started planning a year before work began.

"There is no such thing as over planning. It's key to helping homeowners stay on budget," said Daniel Diclerico, Home Editor for Consumer Reports.

But general contractors say homeowners make common mistakes, adding cost and aggravation.

Fifty-nine percent surveyed by Consumer Reports said homeowner indecisiveness was at the top of their list of biggest mistakes.

Changing your mind once the work begins can really bust your budget.

Just ask Loizeaux, who opted to re-do her kitchen midway through her renovation.

"I think adding the kitchen probably added another 15 to 20 percent to the budget," she said.

Before her kitchen was finished, she faced a second common cause of cost overruns: uncovering damage.

"When I found out about the gas leak, I wanted to cry. We were a week away from moving in," she explained.

"Getting a pre-inspection can really help avoid unwanted surprises. It's useful knowing problems beforehand so you can adjust your budget accordingly," said Diclerico.

And don't forget, it's a mistake not to bargain. Thirty percent of the contractors surveyed say they are very willing to negotiate.

And no matter what you think the renovation will cost, be sure to build in some padding.

"Homeowners should assume their project will cost 20 percent more than you expect and take 20 percent longer than planned," he said.

And that happened to Loizeaux.

"We had to move in before the house was finished. It's a stressful process. But we're really happy with it," she said.

So, how long should a renovation take? On average, bathrooms task two weeks and a kitchen can up to three weeks.

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Consumer Reports is published by Consumers Union. Both Consumer Reports and Consumers Union are not-for-profit organizations that accept no advertising. Neither has any commercial relationship with any advertiser or sponsor on this site.

(All Consumer Reports Material Copyright 2014. Consumers Union of U.S. Inc. ALL RIGHTS RESERVED.)