Avoid amateurs for bathroom renovation.

• Position: Home Improvement

The homeowner improvement and repair market is expected to reach $317,000,000,000 this year, and the number of individuals utilizing do-it-yourself and unlicensed contractors for renovations also is on the rise. Some 13% of all households undertook a bathroom remodel or replacement project in 2016 and, of those, 42% failed to use a licensed contractor. The risks associated with improper renovations--especially tiling--not only can slash a home's value, but prove hazardous for homeowners' health, warns Greg Norman, founder of the Florida and Virginia renovation company BathMasters.

When it comes to bathroom overhauls, homeowners generally are unprepared for surprises, such as mold or leaks that can be hiding inside walls and beneath floors. Improper tiling performed by a homeowner or unlicensed contractor can inadvertently allow water to seep in, facilitating accumulation of mold spores--thereby causing serious damage to a homeowner's house and health. Statistics show that, in all remodeling projects, tile showers are the No. 1 botched renovation.

Norman says the room for error is vast. If the underside of the shower pan is not waterproofed, or the membrane going to the drain is installed improperly...