SIMPSON Strong-Tie LSTHD Wood Construction Connectors Instructions

: June 9, 2024
: Simpson Strong-Tie

Table of Contents

Strap Tie Holdowns
StrapMate®
Documents / Resources

LSTHD Wood Construction
Connectors Instructions

Strap Tie Holdowns

This product is preferable to similar connectors because of (a) easier installation, 2,) higher loads, (c) lower installed cost, or a combination of these features.
The STHD is an embedded strap-tie holdown offering high load and a staggered nal pattern to help minimize splitting. The STHD inco-poraies many features that aid coitect installation and improve perfo n tance. When installed on the :orms with the StrapMate® strap holder The i nigt e design of the STHD delivers enhanced stability before and di wing the pocir to help prevent both parallel and perpendicular movement (relative to the form). This results in accurate positioning of the strap and reduced possibility of spalling.

Featurn

The pattern allows for nailing to the edges of double 2x’s
Strap nail slots are countersunk to provide a lower nail head profile
The slots below the embedment line enable increased front-to-oack concrete bond and help to reduce spalling
Rim joist (RJ) models accommodate up to a 17″ clear span without any loss of strap nailing

Material: LSTHD£ , LSTHD8RJ — 14 gauge; all others — 19` gauge
Finisn: Galvanized
Installation:

See Holdown and Tension Tie General Notes on pp. 49-50.
Use tables for both standard concrete and post-tension slab installations.
Install before concrete pour with a StrapMate, or other holding device.
Nail strap from the bottom up. Install strap plumb.
Strap may be bent one full cyde (bent horizontal 90° then bent vertical) to aid wall placement, but may cause spalling behind the strap. If the spall is 1″ or less, measured from the embedment line to the bottom of the spall, full loads apply 1′ to 4″ spalls for LSTHDB achieve 0.9 times table loads. STHD10 and STHD14 achieve full load for spalls less than 4°. Any portion of the strap left exposed should be protected against corrosion.
Other than where noted in the two-pour detail, do not install where: (a) A horizontal cold joint exists within the embedment depth between the slab and foundation wall or footing beneath, unless provisions are made to transfer the load, or the slab is designed to resist the load imposed by the anchor; or (b) Slabs are poured over concrete block foundation walls.
Additional studs attached to the shearwall studs or post may be required by the designer for wall sheathing nailing.
Wood shrinkage after strap installation across horizontal members may cause strap to bucrie outward.
For installations in severe corrosion environments, refer to strongtie.com/cipcorrosion for additional considerations.
See installation illustrations on p. 60 for rebar information.

For Two-Pour Installation for Downturn Footings

For STHL)10 installed through a 4′-thick slab, use the equivalent 8″-stemwall loads of the LSTHD8
For STH014 installed through a 4″-thick slab, use the equivalent 8″-stemwall loads of the STHD10
For STHJ14 installed through a 6″-thick slab, use the equivalent 8″-stemwall loads of the LSTHD8
Codes: See p. 11 for Code Reference Key Chart

SIMPSON Strong-Tie LSTHD Wood Construction Connectors - fig
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SIMPSON Strong-Tie LSTHD Wood Construction Connectors - fig
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Tension Loads for STHD Installation

Min.
Ste’ ‘mail
(in.)| Maas Na.| Strap Length (L)| le (in.)| equi-e ai s
(in.)| Uncracked| Cracked| Code
Ref.
---|---|---|---|---|---|---|---
Stanuard| Rim .hist| Standard
(ie.)| Rh., ,;oist
(in.)| Midwall Corner| cndwall| Midwall| Corner| Endwall
Wind and SIC AU – Allowable Tension Loads for bF/SP/S1r/HF (160)| it
6| LSTHD8| LSTHD8RJ| 18-:5| 321/2| 8| (20) 0.148 x 31/2| 2,985| 2,510| 1,6-0| 2,565| 2,225| 1,395| IBC, FL
STHD10| 8 ihD1ORJ| 24%| 3814| 10| (24) 0.148 x 31/2| 3,535| 3,535| 1,960| 2,910| 2,910| 1,635
STHD14| STHD11RJ| 261/2| 39%| 14| (30) 0.148 x 31/4| 1,935| .7,935| 3,065| 4,935| 4,935| 3,065
is| LSTHD8| LSTHD8RJ| 18%| 321A3| 8| (20) 0.148 x 31/4| 2,985| 2,590| 2,135| 2,565| 2,225| 1,835
STHD10| STHDIORJ| 24%| 381/2| 10| (28) 0.148 x 31/2| 4,755| 4,075| 3,015| 4,020| 3,350| 2,480
STHD14| CTHDI4RJ| 261/2| 39%| 14| (30) 0.148 x 31/2| 5,285| 5,285| 4,410| 5,285| 5,285| 4,410
| | SDC C-F – Allowable Tension Loads fo DFISP/SPF/HF (160)|
6| LSTHD8| LSTHD8RJ| 18%| 321/2| 8| (16) 0.148 x 31/2| 2,270| 2,090| 1,220| 2,250| 1,950| 1,220| 113C, FL
STHD10| STHDIORJ| 24%| 38%| 10| (18) 0.148 x 314| 2,750| 2,750| 1,615| 2,550| 2,550| 1,435
STHD14| ST1-1014RJ| 261/2| 39%| 14| (22) 0.148 x 31/4| 3,695| 3,695| 2,685| 3,695| 3,695| 2,685
8| LSTHD8| LSTHD8RJ| 18%| 321A3| 8| (16) 0.148 x 31/4| 2,615| 2,125| 1,635| 2,250| 1,950| 1,610
STHD10| STHDIORJ| 24%| 381/2| 10| (20) 0.148 x 31/4| 3,400| 2,940| 2,295| 3,400| 2,940| 2,115
STHD14| STHDI4RJ| 261/2| 39%| 14| (24) 0.148 x 3%| 3,815| 3,815| 3,500| _ 3,815| 3,815| 3,500

Allowable loads have been ir.creased for wind or earthquake loading with no further increase allowed. Reduce where other lads govern.
Concre.e shall have a I rinimum co npressive strength off- 2,500 psi.
0.148″x 3′ or 0.148′ x 2 1/2′ nails ma, be used as a direct replacement for the required nails shown in the table with no load reduction when they are installed directly over framing or over W maximum struct Aral sheathing.
Lse the number of nails listed in the table or as oiherwise specilled. In many cases, not all nail holes will be filed. Nail strap from the bottom up.
Defection at the highest allowable loads for installations over wood double studs is as follows: Installed on framing: LSI HD8 = 0.089°. STFID10 = 0.117′, and STHD14 = 0.118″. Installed over 1/2′ maximum structural sheathing: L.STHD8 = 0.114% STHD10 = 0.146′, and STHD14 = 0.164″.
To obtain LRFD values, multiply ASD seismic load values by 1.43 and wind load values by 1.67.
Per 2012, 2015. 2018 and 2021 IBC, Section 1613.1, detached one- and two-family dwellings in Seismic Design Category (SDC) C may use ‘Wind and SOU MB” allowable loads.
Minimum center-to-center spacing is three times the required embedment, 3 x ie. for STHD strap-tie holdowns acting in tension sinultaneously. Midwall installation is based on 1.5 x le end distance.
See technical bulletin T-C SCLCLM at strongtie.com for installation on structural composite lumber posts or columns.
For brick ledge appications, use full loads shown for STHD14 installed in 8″ stem wall.
For stab-on-grade installation, use full loads shown for LSTE_PSTH9 installed in 8′ sternwall.
Faster” s• Nail dimensions are listed diameter by length. See pp. 21-22 for fastener information.

Spell Reduction System for STHD Holdown
Features

built-in tab
StrapMate® locator line
Additional diamond hole in RJ versions

Benefits Built-in Tab :

Reduces spalling and costly retrofits
No additional labor to install
Holds STHD away from form board

StrapMate Locator Line:

Easy inspection to ensure proper location
Allows adjustment without removing STHD

Additional Diamond Hole:

One more fastener to help prevent the STHD RJ models from bowing out at the rim joist section

SIMPSON Strong-Tie LSTHD Wood Construction Connectors - fig
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SIMPSON Strong-Tie LSTHD Wood Construction Connectors - fig
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StrapMate®

Strap Holder
The StrapMate is designed to keep the STHD and LSTHD straps vertically aligned during the concrete pour to minimize possibility of spalling. The friction fit allows for quick and easy installation.

Features:

The StrapMate is reusable
Works with STHD, LSTHD
Designed to fit 3⁄4″ plywood forms up to 1 3⁄4″ LVL forms and larger
The strap is positioned off the front edge of the form board Material: Engineered composite plastic

Model No.	Nails (in.)
SM1	(2) 0.131 x 2 1/2 Duplex

This product is preferable to similar connectors because of a) easier installation, b) higher loads, c) lower installed cost, or a combination of these features.

The STHD is an embedded strap-tie holdown offering high-load capacity.
The STHD incorporates many features that aid correct installation and improve performance. When installed on the forms with the StrapMate® strap holder, the unique
design of the STHD delivers enhanced stability before and during the pour to help prevent both parallel and perpendicular movement (relative to the form). This results in accurate positioning of the strap and reduced possibility of spalling.

Features

The fastener pattern allows for fastening to the edges of back-to-back studs
Strap nail slots are countersunk to provide a lower nail head profile
The slots below the embedment line enable increased front-to-back concrete bond and help to reduce spalling
Rim joist models accommodate up to a 17″ clear span without any loss of strap fastening
Material: LSTHD8, LSTHD8RJ — 14 gauge, all others — 12 gauge
Finish: Galvanized Installation:
Use all specified fasteners; see General Notes.
Use table below for both standard concrete and post-tension slab installations.
Install before concrete pour with a StrapMate® or other holding device.
Fasten strap from the bottom up.
Strap may be bent one full cycle (bent horizontal 90° then bent vertical) to aid wall placement, but may cause spalling behind the strap. If the spall is 1″ or less, measured
from the embedment line to the bottom of the spall, full loads apply. 1″ to 4″ spalls for LSTHD8 achieve 0.9 times table loads. STHD10 and STHD14 achieve full load for spalls less than 4″. Any portion of the strap left exposed should be protected against corrosion.
Other than where noted in the two-pour detail, do not install where: (a) a horizontal cold joint exists within the embedment depth between the slab and foundation wall
or footing beneath, unless provisions are made to transfer the load, or the slab is designed to resist the load imposed by the anchor; or (b) slabs are poured over concrete block foundation walls.
Additional studs attached to the shearwall studs or post may be required by the designer for wall sheathing fastening.
For installation in severe corrosion environments, refer to strongtie.com/cipcorrosion for additional considerations.
Codes: See p. 11 for Code Reference Key Chart

SIMPSON Strong-Tie LSTHD Wood Construction Connectors - fig
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Allowable Stress Design (ASD) Loads for STHD Strap Style Hold-Downs on CFS — 2,500 psi Concrete

Wind and SDC A & B – Allowable Tension Loads (lb.) – 33 mil (20 ga.) Studs| Code
Ref.
---|---
Min.
Stem
Wall
(in.)| Model No.| Strap Length (L)| le
(In)| Non-Cracked| Cracked
Standard| Rim Joist| Standard
(In•)| Rim
Joist
(in.)
Req’d Screws| Midwall| Corner| Endwall| Req’d Screws| Midwall| Corner| Endwall
6| LSTHD8| LSTHD8RJ| 18%| 32%| 8| (20) #10| 2,985| 2.590| 1.620| (16) #10| 2,565| 2.| 1,395| BC,
LA, FL
STHD10| STHD1ORJ| 24%| 38%| 10| (24) #10| 3,535| 3,535| 1,960| (22) #10| 2,910| 2,910| 1,635
STHD14| STHD14RJ| 26%| 3936| 14| (30) #10| 4,935| 4,935| 3,065| (30) #10| 4,935| 5.| 3,065
| | | | | | | | | | | | |
8| LSTHD8| LSTHD8RJ| 18%| 32%| 8| (20) #10| 2,985| 2,590| 2.| (16) #10| 2,565| 2,225| 2.
STHD10| STHD1ORJ| 24%| 38%| 10| (28) #10| 4,755| 4,075| 3,015| (22) #10| 4,020| 3,350| 2,480
STHD14| STHD14RJ| 26%| 3936| 14| 13011110| 5,285| 5,285| 4,410| (30) #10| 5,285| 5,285| 4,410
SDC C-F -Allowable Tension Loads (lb.) -33 mil (20 ga.) Studs
Min.| Model No.| Strap Length (L)| | |
Stem
Wall| Standard| Rim Joist| Standard| Rim
Joist| le
(In )| Non-Cracked| Cracked
On.)| | | (in.)| (In.)| | Req’d Screws| MISS!| Corner| Endwall| Req’d Screws| Midwall| Corner| Endwall
| LSTHD8| LSTHD8RJ| 18%| 32%| 8| (16) #10| 2.270| 2,090| 1,220| (14) #10| 2,250| 1.950| 1.220
6| STHD10| STHD1ORJ| 24%| 38%| 10| (18) #10| 2,750| 2,750| 1,615| (18) #10| 2,550| 2,550| 1,435
| STHD14| STHD14RJ| 26%| 3936| 14| (22) #10| 4.| 3,695| 2,685| (22) #10| 3,695| 3,695| 2,685
| | | | | | | | | | | | |
| LSTHD8| LSTHD8RJ| 18%| 32%| 8| (16) #10| 2,615| 2,125| 1,635| (14) #10| 2,250| 1.950| 1,610
8| STHD10| STHD1ORJ| 24%| 38%| 10| (20) #10| 3,400| 2,940| 2,295| (20) #10| 3,400| 2,940| 2,175
| STHD14| STHD14RJ| 26%| 3936| 14| (24) #10| 3,815| 4.| 3,500| (24) #10| 4.| 3,815| 3,500

Deflection at highest allowable loads for install over CFS double studs are as follows: LSTHD8 = 0.065″, STHD10 = 0.096″ and STHD14 = 0.115″.
Multiply Seismic and Wind ASD load values by 1.4 or 1.67, respectively, to obtain LRFD capacities.
Per 2012, 2015 and 2018 IBC Section 1613, detached one- and two- family dwellings assigned to Seismic Design Category (SDC) A, B or C are exempt from the seismic design provisions of IBC Section 1613. For this case, the allowable wind loads apply.
Minimum center-to-center spacing is 3 times the required embedment (Smin = 3 x le) for STHD’s acting in tension simultaneously. Midwall install is based on 1.5 x le end distance.
See Fastening Systems catalog (C-F-2019) on strongtie.com for more information on Simpson Strong-Tie fasteners.

SIMPSON Strong-Tie LSTHD Wood Construction Connectors - fig
9

Spall Reduction System for STHD Holdown
Features

Built-in tab
StrapMate® locator line
Additional diamond hole in RJ versions

Benefits Built-in Tab:

Reduces spalling and costly retrofits.
No additional labor to install.
Holds STHD away from form board.

StrapMate Locator Line:

Easy inspection to ensure proper location.
Allows adjustment without removing STHD.

Additional Diamond Hole:

One more fastener to help prevent the STHD RJ models from bowing out at the rim joist section.

Documents / Resources

| SIMPSON Strong-Tie LSTHD Wood Construction Connectors [pdf] Instructions
LSTHD, STHD, LSTHD Wood Construction Connectors, LSTHD, Wood Construction Connectors, Construction Connectors, Connectors
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