Fix Now, Save (A Lot) Later

Potential problem: Puckered, missing, or shrunken caulk can allow water to seep into a wall cavity, leading to mold or even wall failure. Likewise, a chunk of missing grout in a tub surround can cause serious water damage behind the tiles.

Fix it now: Recaulking a bathtub is one of the simplest DIY projects. All you need is a $6 tube of mildew-resistant silicone. While you're at it, touch up the grout using a premixed compound, which runs about $10 per quart. For bigger jobs, mix your own using a $12 bag of polymer-fortified grout powder. Follow the maker's instructions to mix in just the right amount of water—too little makes grout crumbly, too much will make it cure improperly.

What you'll save: Up to $2,500 to retile a small section, including partial demolition of the wall and new backer board. Long-neglected leaks could necessitate a $200 to $900 mold inspection, plus $2,000 to $6,000 for remediation if toxic mold is found.

DIY: Find foolproof caulk and grout tips.