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Simpsons Strong-Tie THA hangers for underslung joists

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April 27, 2018
Re: Allowable Loads for Simpson Strong-Tie® THA Hangers Supporting Joists That Hang Below the Header
This letter provides allowable loads for the face-mount installation of Simpson Strong-Tie THA adjustable truss
hangers when the supported member hangs either partially or entirely below the header as shown in Figures 1 and 2.
For top-flange installation options, refer to the Wood Construction Connector catalog.
The table below provides allowable loads for alternate THA face-mount fastening schedules that are not shown in the
Wood Construction Connectors catalog. Also included is the THAI-2 maximum nailing configuration. Tabulated
allowable loads are for downward gravity loads only. For applications involving suspended wood joists from a header
above the joists, bracing or other means of lateral and torsional support must be provided. Design of bracing systems
must be in full compliance with governing building code requirements and must be performed by a qualified design
professional when required by the jurisdictional authority.
Allowable Loads for Face-Mount Installation with Joist Hanging Below Header
Dimensions (in.)
Model
No.
W
H
Face
Joist
2x Truss/
Joist
2-2x
Truss/
Joist
THA213
THA218
THA218-2
1 5/8
1 5/8
3 1/8
13 5/16
17 3/16
17 11/16
(10) 10d
(10) 10d
(20) 10d
THA222-2
3 1/8
22 3/16
(20) 10d
3 5/8
13 5/16
2.
3.
4.
5.
6.
Allowable Loads (lbs.)
Floor
(100)
DF/SP
Snow
(115)
Floor
(100)
SPF/HF
Snow
(115)
Roof
(125)
Roof
(125)
(4) 10dx1 ½”
(4) 10dx1 ½”
(6) 10dx1 ½”
1,180
1,180
2,440
1,200
1,200
2,485
1,200
1,200
2,485
1,020
1,020
2,100
1,160
1,160
2,140
1,200
1,200
2,140
(6) 10dx1 ½”
2,440
2,485
2,485
2,100
2,140
2,140
1,180
1,200
1,200
(10) 10d
(4) 10dx1 ½”
1,020
1,160
1,200
(20) 10d
(6) 10dx1 ½”
2,440
2,485
2,485
2,100
2,140
2,140
3 5/8
17 1/2
(20) 10d
(6) 10dx1 ½”
2,440
2,485
2,485
2,100
2,140
2,140
22 1/16
3 5/8
(30) 10d
(6) 10dx1 ½”
3,225
3,225
3,225
2,770
2,770
2,770
3 5/8
26 1/16
3 1/8 to
11
3”-5 ¼”
THAI-2
(30) 10d
(2) 10dx1 ½”
3,780
4,260
4,425
3,270
3,540
3,540
21 /16
5 5/16
Loads are based on a min. 2-ply 2x carrying member (multiple plies must be fastened together independently of the hanger fasteners to act as one unit to resist the
applied load). 10dx2 ½” nails may be used instead of the specified 10d commons at 0.85 of the table load. For single-ply 2x or 1 ¾” wide carrying members, use
10dx1 ½” nails and use 0.77 of the table value. Alternately, SD #9 x1 1/2" screws may be used in place of the specified header and joist nails for full table loads.
At least half of the face fasteners must be installed into the upper half of the header, unless some other means of mechanical reinforcement is used to resist the
tension perpendicular to grain stresses. Nails must have a minimum 1/2” edge distance.
THA models: the joist nails should be installed straight into the carried member by straightening the THA double shear nailing tabs. When used to support 2x4
joists, the THA213 or THA218 may be installed with (2)10dx1 ½” nails into the joist (one each side).
THAI-2: Specify W dimension for hanger width needed; W should be ordered 1/16” to 1/8” greater than the joist width.
For installations with fewer face fasteners than specified, reduce the allowable load as follows:
Allowable load = No. of Face Nails Used/No. Face Nails in Table x Table Load
NAILS: 10d = 0.148" dia. x 3" long, 10dx1 1/2" = 0.148" dia. x 1 1/2" long.
4x Truss/
Joist
1.
Fasteners
Joist
Size
THA413
THA418
THA422
THA426
Figure 1 – THA218 Supporting Suspended Joist
Page_1_of_2
Figure 2 – THA422 supporting floor truss that is
deeper than the header
L-C-THAALT18
Simpson Strong-Tie Company Inc. 5956 W. Las Positas Boulevard Pleasanton, CA 94588 Phone: 925.560.9000 Fax: 925.847.1605 www.strongtie.com
Example 1: 24” deep floor truss with 2000-lb. reaction framing into 1 ¾” x 11 7/8” LVL Ledger
Try THA418 (Allowable load = 2,440 lbs.)
Step 1 - Check Strap Length (footnote 2):
THA418: Straps do not extend beyond the centerline of the
carrying member NG
Try THA422: Straps extend past the centerline by enough
distance to install 16 face fasteners (8 ea strap) above the
centerline
Step 2 - Determine allowable load based on number of face fasteners
that can be installed (footnotes 2 and 5):
THA422: Allowable load with 20 face fasteners = 2, 440 lbs.
Step 3 - Adjust allowable load for single-ply header (footnote 1):
THA422 with (20) 10dx1 ½” nails Allowable load = 2, 440 x
0.77 = 1,879 lbs. < 2000 lbs. NG
THA422 with (20) SD#9x1 ½ Allowable load = 2, 440 lbs. >
2000 lbs. OK
Example 2: 2x10 joist with 800-lb. reaction suspended from 2-2x10 SPF Header
Try THA213 (Allowable load = 1,020 lbs.)
Step 1 - Check Strap Length (footnote 2):
THA213: Straps do not extend beyond the centerline of the carrying
member NG
Try THA218: Straps extend past the centerline by enough distance
to install 4 face fasteners (2 ea strap) above the centerline
Step 2 - Determine allowable load based on number of face fasteners
that can be installed (footnotes 2 and 5):
THA218: Allowable load with 8 face fasteners = 8/10 x 1,020 lbs. =
816 lbs. > 800 lbs. OK (Note: Bracing or other means of lateral and
torsional support must be provided for joist)
The information in this letter is valid until 4/30/2019 when it will be re-evaluated by Simpson Strong-Tie. Please visit
www.strongtie.com for additional pertinent information. If you have questions or need further assistance regarding this
matter, please contact the Simpson Strong-Tie engineering department at 800.999.5099.
Sincerely,
SIMPSON STRONG-TIE COMPANY INC.
Page_2_of_2
L-C-THAALT18
Simpson Strong-Tie Company Inc. 5956 W. Las Positas Boulevard Pleasanton, CA 94588 Phone: 925.560.9000 Fax: 925.847.1605 www.strongtie.com
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