Top 10 mistakes of DIYers

The standard rule with do-it-yourself projects is that the projects will take twice as much time and three times as much money as you thought they would -- or maybe it's three times as long and twice as much money.

Either way, the reason for that is the same. DIYers make mistakes. Lots of them. The good news is that you can learn a lot from mistakes. For example, whatever it was that my husband did to make all the outlets in the kitchen blow at the same time -- don't do that again. The bad news is that mistakes always wind up making your home-improvement project more expensive and more time-consuming than you want it to be.

With that as a given, Bankrate.com asked home-improvement experts for their lists of the top DIY goofs, with advice on how to avoid repeating the errors in the future.

The experts are:

• Ed Del Grande, host of the DIY Network's "Warehouse Warriors" show, as well as other shows and building specials on the network. A master plumber, pipe fitter and fire-sprinkler fitter, Del Grande has more than 20 years of construction experience.
• Lou Manfredini, the official Ace Hardware "Helpful Hardware Man." (You didn't think it was John Madden, did you?) The home-improvement expert for NBC's "Today" show, the Chicago-based contractor also answers questions from DIYers on the Ace Hardware Web site.
• C.J. Iannuzzi, owner of 3SQFT, a design-build company in Miami Beach, Fla., and home-improvement contractor to the stars, including Madonna, Rosie O'Donnell, Gloria Estefan and Ricky Martin.
• Barbara Kavovit, owner of Barbara K Enterprises. A New York City-based veteran of the construction industry, she now makes and markets DIY tools especially designed for women.

1. Not taking out the required permits. This is a big issue with both Del Grande and Manfredini. Considered a bother at best by many DIYers, permits actually serve a greater purpose than just raising money for the government. "People in permitting offices aren't evil," says Manfredini. "They're there to make sure the job is done right and you don't hurt yourself." Plus, for some jobs, such as putting in a wood stove, you need proof of the permit or your insurance carrier won't cover it. Not sure if your job requires a permit? Del Grande says that the rule of thumb is that you need one for anything larger than painting and wallpapering. It doesn't hurt to call the building department and ask.

2. Starting a job without the necessary tools and supplies. Nothing slows down a job more than not having all the materials you need. Manfredini says that the reason the pros can do what they do is that they buy quality tools. "There's always a bargain bin," he says. "It's not a wise investment. You lose time and money."

3. Inadequate preparation of the job site. If you do a small addition, suppliers will be delivering materials. You don't want them out of order or exposed to the weather while you are working, Del Grande says. Beware: They could be stolen if they're not properly stored. (If you have a septic tank, make sure you know where it is. If a supplier delivering materials in a heavy truck drives over it, you could be looking at a cracked tank. Yuck.)

4. Skimping on materials. Kavovit says she often sees DIYers use 1/4-inch drywall for building walls. You need to use at least 5/8-inch; 3/4-inch works well for a good sound barrier. The same rule applies to plywood for subfloors. Go with 3/4-inch. It creates a much stronger floor, especially if you're installing wood floors over them.

5. Using the wrong paint. One of the biggest DIY projects around, painting can make a place look great. Manfredini says flat paint should only be used for ceilings. Interior paints should have at least an eggshell or satin finish so you can scrub it. On outdoor decks, "sun and rain tear the heck out of the wood," he says. Clear sealers don't block the UV rays, and they peel. Use a linseed-oil-based stain; it drives the pigment into the wood and preserves it.

6. Improper preparation of walls for painting. A good, quality paint job is 90% preparation, Manfredini says. Clean the walls, sand them and patch any holes before you paint. Iannuzzi recommends a coat of primer or stain blocker if you're trying to cover over oil-based paint, stains or peeling paint, or if you're painting a lighter color over a darker color.

7. Unsafe job conditions. Nothing diminishes your return on investment like a trip to the emergency room. Wear safety goggles when using power tools or working with drywall or wood, wear hard hats when you're working under other people on scaffolding, and open some windows when you're painting or staining, or stripping old finishes off of floors or walls, Del Grande says. Iannuzzi cautions against wearing loose, hanging clothing, especially when using power tools. Wear gloves when carrying wood, metal and rock, or when hammering, and wear a nail or tool pouch to prevent damage to your floors and more important, the feet of people and pets.

8. Inaccuracy. Iannuzzi lives by the rule: Measure twice, cut once. It's so important for things like building walls, hanging drywall or cutting baseboards, counter tops or pipe. If you're going to err, err on the side of too long. You can always make something shorter; you can't make it longer. Spackle can cover up to a 1/8-inch seam, Iannuzzi says; if it's a 1/4 of an inch, the seam will pop the spackle and show.

9. Working beyond your limits. Everybody has them. Del Grande won't work on a roof; yours might be plumbing or electrical work. Don't stand on the top steps of ladders, and don't try to work beyond your reach. Ladder accidents send more than 164,000 people to the emergency room every year, according to the U.S. Consumer Product Safety Commission.

10. Failure to get a clue. You don't want to start to learn how to do a project on your own house. If you have a friend who is a contractor or an experienced DIYer, offer your assistance on one of his projects so you can learn. No one will turn away free labor. If you need to remove a supporting wall, have an engineer look at it to see what kind of beam you need to replace it. "If you have a saw in your hand and have a question about what you're doing," Del Grande says, "stop. Follow that little voice in your head."