8 critical home repairs you can't ignore

Leaky roof

You know you've got a problem when: A wet or discolored spot appears on the ceiling.

What causes it: Broken or missing shingles, or a crack in the flashing used to seal chimneys, skylights and vent pipes.

The worst that can happen: Structural damage in the attic that rots the decking, beams and joints, and allows mold to grow in your insulation.

Fix it yourself? You have to be able to find the leak, which can be tricky. The water rarely comes in directly above the damage you see inside and there can be more than one source of seepage. Then you'll need some basic carpentry skills and the ability to work on a steeply pitched roof.

Who should you call? A roofer.