Right and Wrong Ways of Siding Installation

Posted by in Roof, Shingles, Siding | January 07, 2019

There is a right way and a wrong way to do most tasks in life. This is also true when it comes to the installation of vinyl or aluminum siding on a wall above a roof slope.   It is good construction practice to provide a space between the bottom edge of the siding and the top of the shingles to allow roof and siding runoff to flow unobstructed to the gutter and to provide kick-out flashing at the eave (Figures SD-1 and SD-2). Kick-out flashing directs runoff onto the exterior of the siding and into the gutter.

Figure SD-1 Siding set approximately 1-inch above surface of the
shingles to allow runoff to flow freely to eave.

Figure SD-2 Kick-out flashing installed at eave to direct runoff into gutter
instead of behind siding.

On the other hand, it is poor construction practice to set siding tight to the surface of the roof and to set the last piece of step flashing behind the siding at the eave (Figures SD-3 and SD-4). These poor siding details promote the infiltration roof and siding runoff behind the siding and under the shingles which typical results in the leakage on the interior of the dwelling. Additionally, the occurrence of leakage on the interior of the dwelling may lead the building owner to fill the J-channel with sealant in an attempt to stop the leakage (Figures SD-3 and SD-4) which may further direct roof and siding runoff behind the siding and under the shingles.

Figure SD-3 Siding set tight to surface of roof. Also, J-channel filled with sealant.

Figure SD-4 No kick-out flashing provided at eave. Runoff is being directed behind siding.  Note large amounts of sealant applied along bottom edge of siding.

It hurts to even look at these last two photos.