Chamberlain LiftMaster Security + 3270 1/2 HP Manuel D'instructions page 9

INSTALLATION STEP 2
Install the Header Bracket
You can attach the header bracket either to the wall above
the garage door, or to the ceiling. Follow the instructions
which will work best for your particular requirements.
Do not install the header bracket over drywall.
If installing into masonry, use concrete anchors
(not provided).
WALL HEADER BRACKET INSTALLATION
1. Center the bracket on the vertical centerline with the
bottom edge of the bracket on the horizontal line as
shown (with the arrow pointing toward the ceiling).
2. Mark the vertical set of bracket holes (do not use the
holes designated for ceiling mount). Drill 3/16" pilot
holes and fasten the bracket securely to a structural
support with the hardware provided.
HARDWARE SHOWN ACTUAL SIZE
CEILING HEADER BRACKET INSTALLATION
1. Extend the vertical centerline onto the ceiling as shown.
2. Center the bracket on the vertical mark, no more than 6"
(15 cm) from the wall. Make sure the arrow is pointing
toward the wall. The bracket can be mounted fl ush
against the ceiling when clearance is minimal.
3. Mark the side holes. Drill 3/16" pilot holes and fasten
bracket securely to a structural support with the
hardware provided.
Lag Screw
5/16"-9x1-5/8"
Ceiling Mounting Holes
Wall Mounting Holes
Optional
Wall Mounting Holes
Header
— Header Wall —
Bracket
2x4
Structural
Support
Horizontal
Line
Highest Point of
Garage Door Travel
— Finished Ceiling —
6" (15 cm)
Maximum
Door
Spring
Garage Door
9
Vertical
Centerline
of Garage Door
Lag Screws
5/16"-9x1-5/8"
Door Spring
— Garage Door —
Vertical
Centerline
of Garage Door
Vertical
Centerline
of Garage Door
Header
Bracket
Lag Screws
5/16"-9x1-5/8"
— Header Wall —
Vertical
Centerline
of Garage Door