I-JOIST HEADER CROSS-SECTION
E4
F10
Verify web filler/
stiffener requirments
for hangers
Filler
block(s)
Backer Block
(or Web Filler)
Supported hanger
(top-mount shown)
Filler Blocks:
Fasten I-Joists together with filler blocks between the LPI webs using 2 rows of 0.131"x3.25"
nails at 6" o.c. from both sides, stagger rows, and clinch where possible.
Refer to the I-Joist Filler Thickness table for the correct filler block thickness for each LPI series.
Filler blocks must be at least 4' long, located at each support, and centered behind each hanger.
For joists supporting only top loads that are equally applied to both plies, filler blocks can be
spaced at 8' on center maximum.
Backer Blocks:
Fasten min. 12" long backer blocks at all hangers and concentrated loads, center backer block
on load, using a minimum of 10 nails (0.131"x3.25", clinch where possible) spaced to avoid
splitting with half the nails to each side of the center of the supported hanger.
Refer to the I-Joist Filler Thickness table for the correct backer block thickness for each LPI series.
For a single I-joist header, install backer blocks to both sides of the web.
Backer blocks may be omitted for top-mount hangers supporting only downward loads not
exceeding 250 lbs.
Install backer blocks tight to top flange for top-mount hangers or top concentrated loads unevenly
applied to both plies. Install tight to bottom flange for joists supporting face-mount hangers.
NOTES:
1. For double LPI’s the maximum “Side-Applied” unfactored loads for standardard duration: Uniform Load = 520 plf, Concentrated Load = 1200 lbs.
Loads may be increased with more nails, and adjusted for other load durations.
2. Filler and backer blocks shall consist of APA Rated wood structural panel (OSB or plywood), 2 x lumber (SPF or better) or
LP® SolidStart® LVL, LSL or OSB Rim Board.
3. Filler and backer blocks for members that are top-loaded only, or for hangers that do not require nailing into the web, shall be at least 5-1/2"
deep for I-joists to 11-7/8" deep, and shall be at least 7-1/4" deep for I-joists 14" and deeper. Otherwise filler blocks shall fit the clear
distance between flanges with a gap of at least 1/8", but not more than 1".
Filler Block Example: Lumber fillers may be stacked to achieve the required depth. Two 2 x 8s may be stacked vertically to achieve the filler depth
for an 18" deep I-joist (min. req. is 18"–3"–1"=14"). One row of nails must be in each row of stacked fillers.
Backer Block Example: Two pieces of 2 x 8 (min.) lumber, cut to the proper height, may be set vertically side-by-side to achieve the required
minimum 12" length.
LP I-Joist Filler Thickness Table
Series Filler Backer
LPI 18, 20Plus, 32Plus 2-1/8" 1"
LPI 36 1-7/8" 7/8"
LPI 42Plus, 52Plus, 56 3" 1-1/2"
LPI 450 1-1/2" 23/32"
LPI 530 1-3/4" 7/8"