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I-JOIST HEADER CROSS-SECTION
Verify web filler / stiffener
requirments for hangers
Filler
block(s)
Web filler
(as backer block)
E4
Supported hanger
(top-mount shown)
NOTES:
1. Backer blocks and filler 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, with a net thickness equivalent to that shown in the I-Joist Filler Thickness table below.
2. Except as noted in 3, backer blocks and filler blocks shall fit the clear distance between flanges with a gap of at least 1/8," but not more than
1," and shall be of sufficient depth to allow for all hanger nailing into the web. Do not force into place.
3. Backer blocks and filler blocks for double I-joists that are top-loaded only or side-loaded supporting top-mount 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.
4. Install backer blocks tight to top flange for top-loaded joists and for joists supporting top-mount hangers (shown). Install tight to bottom flange
for joists supporting face-mount hangers.
5. Clinch nails where possible.
6. For double I-joists, additional nailing may be required to transfer point loads. For additional information, contact your LP SolidStart Engineered
Wood Products distributor.
Web Filler/Backer Block: Backer blocks shall be at least 12" long and located
behind every supported hanger. For a single I-joist header, install backer
blocks to both sides of the web. Two pieces of 2 x 8 (min.) lumber, cut to the
proper height (see notes 2 & 3), may be set vertically side-by-side to achieve
the required minimum 12" length.
Attach backer blocks with 8d nails (use 10d nails for flanges wider than 2-1/2").
Use a minimum of 10 nails spaced to avoid splitting, with half the nails to
each side of the center of the supported hanger.
Note: Backer blocks may be omitted for top-mount hangers supporting only
downward loads not exceeding 250 lbs.
Filler Blocks: Install in minimum 4’ long sections at each support, centered
behind each supported hanger and at no more than 8’ oc. Lumber fillers may be
stacked to achieve the required depth (see notes 2 & 3). For example,
Attach filler blocks with 8d nails (10d for flanges wider than 2-1/2") nails
spaced 6" oc per row. Use one row of nails in each row of stacked fillers, with
a minimum of two rows of nails. Drive every other nail from opposite sides.