Wind blown rain entering the siding bottom edge vent drain openings present on most aluminum or vinyl siding can pass behind the siding through those openings.
Water leak behind vinyl siding.
This is a normal condition of these siding products not present on hardboard fibercement board shingle type siding nor plywood sheet siding and is a reason that these siding.
Leaks in other areas of the home besides windows and doors are not as common as they may be for homes with wood siding but they still may happen.
When siding is put back behind the gutter the lowest piece of flashing running down the pitch of the roof above must be fashioned to divert water into the gutter not behind the siding.
Vinyl is a potentially leaky material and water trapped behind siding leads to decay and mold.
Therefore it is not a watertight covering.
How to prevent water from flowing under vinyl siding.
Inspect the area above the leak including both indoors and out.
This article describes the causes of all types of leaks in building siding and wall coverings.
Despite the good qualities of vinyl it does pay to have extra insurance in the form of house wrap.
Check to be sure weep holes are open along bottom of window openings.
Vinyl siding is designed to allow the material underneath it to breathe.
Vinyl siding is designed as an exterior cladding only and is supposed to be installed over other materials such as a weather resistant barrier.
It is possible for moisture and air leaks to enter through these fine lines and seams wreaking havoc behind the siding that you may not even notice until significant damage has already occurred.
Because of its design and application it provides a supplemental rain screen that enhances the water resistive barrier system by reducing the amount of water that reaches the underlying water resistive barrier.
If an installer uses a material such as incorrectly this only exacerbates the problem.
Siding leak diagnosis and repair.
It s virtually impossible to completely seal any siding without additional materials.
In terms of siding this means layering sheeting flashing house wrap caulking siding and trim.
If you do find such an area remove the siding and inspect the walls behind it to determine how the water is getting in.
In this video this old house general contractor tom silva shows how to prevent water from leaking in behind vinyl siding.
