Installation Instructions
CertainTeed Vinyl Siding Installation Guide
81
Cornerposts
Install outside and inside cornerposts using dimensions and 
procedures described on pages 38–41.
NOTE: Unlike the preparation for horizontal siding, do 
not install a starter strip for vertical siding.
Top and Bottom J-Channel
Snap a base line 1" above the low part of the house. 
Apply J-channel along the top and bottom of the walls to 
receive the siding panels. Install the bottom J-channel 
(illustration 1A). Overlap J-channels 3/4". To do this, cut out a 1" 
section of the nailing flange and face return (see illustration 2).
If you prefer to use drip flashing with the J-channel along the 
bottom of the wall, fabricate the lengths you’ll need from aluminum 
coil stock of a color to match the siding (see illustration 1B). 
Install inverted J-channel along the top of the wall, under the eave. 
Here again, leave a 1/4" gap between J-channel and cornerposts. 
Overlap J-channels 3/4" to allow for expansion. When positioning 
the upper J-channel, be sure to allow for expansion of the siding 
panel. In most cases, position the J-channel at a point equal to the 
length of the panel plus 5/8" (1/4" for upper expansion and 3/8" 
for lower expansion).
Soffit
If you’re going to install soffit, you may want to install the receiving 
channels for the soffit at this point. 
The illustrations show alternative approaches for installing siding 
and soffit receiving channels.
1A 1B
1"
Illustration 2
3/4"
soffit
J-channel 
soffit
J-channel 
vertical 
siding
F-channel
vertical 
siding










