There’s an old Yiddish expression that applies to many home improvement projects. Translated, it is: Man plans and God laughs.

You may have a budget in mind for your home improvement project, but until you really get into it, it’s difficult to say whether or not you will stay within that budget. That’s particularly true on larger projects, but even the most innocent of renovations can lead to added costs when a wall is stripped or an unexpected obstacle is encountered.

The odds are against you: only about one in five home improvement projects comes in at or under budget. 

There are some ways you can tip the odds in your favor, however.

Hire a pro. You may consider yourself handy and you may have several kickin’ YouTube videos to help you along, but you may be better off letting a professional handle your project. If you attempt your project on your own, the labor may be free but other expenses can add up. Professionals will know exactly what to expect during any project—from handling permits to coordinating subcontractors—as well as how to deal with the unexpected challenges that inevitably crop up. 

How many times have you had to take a second—or even a third—trip to the home improvement store because you purchased the wrong part? Professionals will get it done right the first time.

Shop around. With all due respect to your buddy Jake or cousin Al, shopping around for a good contractor is a good idea. The best way to ensure your home improvement project will stay under budget is finding the right person to do the work the first time. When you solicit estimates, ask not only about price but qualifications. A major kitchen remodel may require a carpenter, a plumber and an engineer—make sure the company you hire can do it all.

Also, cheaper is not necessarily better. Ask anyone in municipal service—there are plenty of contractors out there who will provide a lowball bid and make up for it through added expenses. 

Make a plan. Whether you attempt your project on your own or hire someone to do it, make sure you plan out every detail and try to anticipate every expense. Don’t forget to add in sales tax, delivery charges, nails and other hardware, etc. Little things add up. 

Prioritize. It’s a good idea to keep track of expenses while a project is under way and develop a list of ‘musts’ and ‘extras.’ By prioritizing the features of your project that are most important to you, you can develop a list of things to cut if expenses rise too rapidly. If you’re remodeling your kitchen, is cupboard space a priority, or the quality of the cabinet doors? If you’re redoing your bathroom, do you need six showerheads with jet propulsion technology, or are you just looking for more space and a shelf for your soap? By planning ahead, you can let your priorities set your budget, not the other way around.

Expect the best, but plan for the worst. Adding in some contingency funds is always a smart idea. Take your ideal budget and add an addition 15-20 percent to it to prepare for unexpected expenses. They are common, particularly in large projects or in older houses. You may open up a wall and discover old wiring that needs to be replaced. Or perhaps the materials you want to use spike in cost due to some unnecessary and unforeseen trade war. 

You may ask: does my home improvement project really come in under budget if I pad that budget before I start? A fair point, perhaps. Do it anyway. You’ll be glad you did.

Despite the amount of planning that goes into any home improvement project, there is usually some guesswork involved. Following these tips will help you keep your project under budget and ensure it’s done properly the first time.