One of the goals of home construction and repair is to ensure that a structure can withstand the elements. Poor workmanship and the effects of time, however, can allow water into a home regardless of the circumstances. If you hear the sound of water running or dripping within your walls when it rains, you need to take action to identify the source of the problem and find a solution before your home experiences even greater and more costly damage.
The sound of water inside your walls can come from two major sources: a roof leak or water that comes through the walls themselves. Masonry walls are susceptible to this problem if the mortar between bricks or stones develops small cracks that wind-blown rain can press through. Roof leaks can channel runoff into your walls instead of shedding it or diverting it into a gutter system. In both cases, the water will gradually drip through your walls' insulation, wetting everything in its path.
When there is enough water in your walls to produce an audible sound, it will affect the framing timber and drywall. If these porous materials become damp, they will eventually soften and lose strength. Water in your walls can also cause mold, which may eventually penetrate into your home and cause a potential health risk for you and your family. Finally, water in your walls indicates another problem with a roof leak or wall cracks that will become worse over time unless you take steps to correct it.
Diagnosing leaks that allow water into your walls during rain can be difficult, especially if the problem only occurs during especially intense storms. For example, rain that leaks through masonry walls may only pose a problem and an audible sound when the rain strikes your home from a certain direction and with enough intensity. Likewise, a roof leak may not pose a problem unless there is enough water on your roof to cause the runoff to rise enough to flow into the space between sheets of roofing material. If you can't identify the source of the leak with a visual inspection, you'll need to note which types of rain cause the sound inside your walls.
Exterior wall leaks that allow water into your walls are generally easier to solve than roof leaks. They require one or more layers of a sealant that covers slight cracks and channels in your masonry. You may only need to apply the sealant to the exterior wall that faces the direction of oncoming storms, or you may need to seal your entire home. Roof leaks may require installing new shingles, sealing cracks or replacing portions of the waterproof sheeting that forms one of the lower layers of the roof. Roof repair is more likely to require professional service and cost more than do-it-yourself wall sealant.