Installation Instructions
CertainTeed Vinyl Siding Installation Guide
83
Wall Panels
Follow the instructions described earlier under the section 
“Preparation for Horizontal Siding” beginning on page 28.
Plan the panel layout
Correctly installed vertical siding should have a balanced 
appearance. This means that if you were to draw a vertical line 
down the center point of a wall, you’d have an equal number of 
panels to the right and left. If you had to trim panels to fit, the 
end-most panels would be of identical width.
To create this pleasing appearance, divide the space to be covered 
by a partial panel over both ends of a wall. For example, if a wall 
required 25 full panels plus 10", you would rip cut two 5" lengths 
of panel to create the end pieces.
Expansion and contraction
In a vertical siding installation, most of the expansion is downward. 
So instead of allowing equal space for expansion at both ends of 
a vertical panel, leave more space at the lower end: allow for 1/3 
of the total expansion at the top of a panel and 2/3 of the total 
expansion at the bottom.
For example, if the total expansion equals 3/4" (3/8" + 3/8"), 
allow 1/4" at the top and 1/2" at the bottom. If the total expansion 
equals 1/2" (1/4" + 1/4"), allow 3/16" at the top and 5/16" at 
the bottom.
NOTE: Always position top most nail at the top of the top 
most full nail slot (1a). Center the remaining nails in the 
slots (1b). When installing siding or accessories vertically, 
make sure the bottom of the panel can expand downward 
without interference.
Cut the first of the partial panels (if partial panels are necessary). 
Mark the cut line by measuring from the nail hem edge. Rip cut the 
panel. Do not cut off the nail hem. Use a snap lock punch to create 
locking tabs along the cut edge. Space the tabs 6" apart.
Before installing this partial panel into the outside cornerpost, 
provide additional support at the cut edge to compensate for 
the locking channel that was trimmed off. 
To do this, insert furring into the channel of the outside cornerpost 
and nail it to the substrate. After furring, insert a length of undersill 
trim into the cornerpost and nail it to the furring. Finally, slide the 
cut edge of the panel into the undersill trim, making sure to engage 
the snap locks (see illustration).
Using a level, make certain this panel is plumb. Nail every 12". 
Follow the same nailing procedures described for horizontal siding.
Allow for 1/3 of 
expansion 
1A
1B
cornerpost
undersill 
trim
snap 
locks
panel
furring
Allow for 2/3 of 
expansion 










