Can Water Leak From Somewhere in My House & Come Out Under My Siding?

Water Damage to Siding

• Most of the damage to your house siding is done by water from the outside. Rain, humidity and watering systems present an immediate threat to the integrity of house siding, although properly installed and finished siding resists these threats efficiently. However, water from inside the home caused by plumbing leaks, construction errors, and even high humidity does attack house siding.

Plumbing Leaks

• Even relatively small plumbing leaks lead to siding damage, regardless of what level of your home the leak occurs in. A leak in a supply line to a bathroom sink causes problems not only in the immediate area, but gravity and water’s natural tendency to flow outward result in moisture reaching the house siding adjacent to the bathroom. The wood wall framing, insulation and drywall between the sink and the exterior walls act as a conduit for leaking water, which eventually drains out through the siding.

Construction Errors

• Concrete slabs are naturally problematic when it comes to water movement. The first problem is improper curing time, which causes moisture to stay in the interior and be transferred to wall and floor framing and covering. Moist building lumber, whether delivered wet or becoming wet when stored outdoors during construction, retains the moisture, which finds its way to the house siding. Faulty water lines leaking under slabs cause water to run outward toward the exterior as well as moistening the soil beneath the slab.

Vapor Barriers

• A vapor barrier may be installed in your home as well, which is often a plastic sheeting material installed inside the exterior walls. The purpose of this is to create a way to prevent moist air flow between the exterior and the interior of your home. However, the vapor barrier must have some way to drain off excess water that results from plumbing leaks or excessive moisture problems inside the home as well as from exterior water from rain or watering. As long as there is an air gap between the coldest side of the wall insulation and the house siding, the vapor will vent out and not turn into excessive moisture that could find its way under the siding.