The first thing any savvy do-it-yourselfer should take into account when considering a new project is that it will probably take twice as much time and three times as much money as you thought. Or maybe it’s three times as long and twice as much money. Either way, there’s a good reason why it’s true: DIYers make mistakes, so we asked home-improvement experts around the country for the most common mistakes a home handyman might make and how to avoid them.

Lots of them. Mistakes such as:

  1. Not taking out the required permits
  2. Starting a job without the necessary tools and supplies.
  3. Inadequate preparation of the job site.
  4. Skimping on materials.
  5. Using the wrong paint.
  6. Improper preparation of walls for painting.
  7. Unsafe job conditions.
  8. Inaccuracy.
  9. Working beyond your limits.
  10. Failure to get a clue.

But you can learn a lot from these mistakes.

Not taking out the required permits

Considered a bother at best by many DIYers, permits serve a greater purpose than just raising money for the government. “People in permitting offices aren’t evil,” says Lou Manfredini, the official Ace Hardware “Helpful Hardware Man.” “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? 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.

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 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.” So make sure to research the tools you’ll need in advance of the job.

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, says Ed Del Grande, author of “Ed Del Grande’s House Call” and former host of the DIY Network’s “Warehouse Warriors” show. 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.)

Skimping on materials

Barbara Kavovit, a do-it-yourself guru and designer of the DIYVA collection of tools and accessories for Macy’s, says she often sees DIYers use 1/4-inch drywall for building walls instead of the minimum 5/8 inch or 3/4 inch if they want 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.

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 because it’s usually not as washable as paints with an eggshell or satin finish. 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.

Improper preparation of walls for painting

A good, quality paint job is 90 percent preparation, Manfredini says. Clean the walls, sand them, and patch any holes before you paint. A coat of primer or stain blocker is advisable 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.

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. And don’t wear 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 importantly, the feet of people and pets.


Successful DIYers live by this rule: Measure twice, cut once. It’s so important for things such as building walls, hanging drywall, or cutting baseboards, countertops, or pipes. 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 only up to a 1/8-inch seam.

Working beyond your limits

Del Grande won’t work on a roof; yours might be plumbing or electrical work.

• Don’t stand on the top steps of ladders.

• Don’t try to work beyond your reach.

Ladder accidents send more than 240,000 people to the emergency room every year, according to the U.S. Consumer Product Safety Commission.

Failure to get a clue

You don’t want to start to learn how to do a project in 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 from 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.