LSTHD/STHD Strap-Tie Holdowns
Strap-Tie Holdowns
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The STHD is an embedded strap-tie holdown offering high load capacity and a staggered nail pattern to help minimize splitting. 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.
Key Features
- The nailing 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-back concrete bond and help to reduce spalling
- Rim joist models accommodate up to a 17" clear span without any loss of strap nailing
Material
- LSTHD8, LSTHD8RJ — 14 gauge; all others — 12 gauge
Finish
- Galvanized
Installation
- Use all specified fasteners; see General Information and Notes for Holdowns and Tension Ties.
- 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 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 nailing.
- Wood shrinkage after strap installation across horizontal members may cause strap to buckle outward.
- For installations in severe corrosion environments, refer to General Corrosion Risks for additional considerations.
- See installation illustrations in the image gallery for rebar information.
For Two-Pour Installation for Downturn Footings
- For STHD10 installed through a 4"-thick slab, use the equivalent 8" stemwall loads of the LSTHD8
- For STHD14 installed through a 4"-thick slab, use the equivalent 8" stemwall loads of the STHD10
- For STHD14 installed through a 6"-thick slab, use the equivalent 8" stemwall loads of the LSTHD8
Related Links
Wood Construction
- Wood Construction Connectors Technical and Installation Notes
- General Information and Notes – Holdowns & Tension Ties
- StrapMate Strap Holder
Cold-Formed Steel Construction
Corrosion Information
Catalog Pages
Related Literature
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Conectores para la construcción en madera 2017–2018C-C-2017SPInformación completa de productos, de la aplicación, de las tablas de cargas y de la instalación, para más de 3,000 conectores de madera a madera, madera a concreto y concreto a mampostería.Catalog -
Connectors for Cold-Formed Steel ConstructionC-CF-2017A catalog including specifications, load tables and installation illustrations for our cold-formed steel connectors and clips.Catalog -
Conectores para construcción de acero moldeado en fríoC-CF-2017SPUn catálogo que incluye especificaciones, tablas de carga e ilustraciones de instalación para nuestras abrazaderas y conectores de acero moldeado en frío.Catalog -
High Wind-Resistant Construction Application GuideF-C-HWRCAG16The newly updated High Wind-Resistant Construction Application Guide offers new applications, updated loads, as well as more fastening information that is used to resist high-wind.Product Guide -
Installer's Pocket GuideS-C-INSTALL16S-C-INSTALL16 is a guide featuring updated products, new color illustrations and easier navigation. Some popular structural fastening and anchoring products have also been added.Installation Guide -
Connector Solutions to Meet the Wall-Bracing Requirements of the 2012/2015 International Residential Code®T-C-WALLBRACE17A technical bulletin providing technical information about wall bracing methods and code sections that require connectors (e.g., holdowns or straps) and anchors.Technical Bulletin -
Connectors Installed on SCL ColumnsT-C-SCLCLM16A one-page, single-sided technical bulletin discussing the structural properties of the two different surface sides of SCL columns, including the listing of reduction factors.Technical Bulletin -
Connectors Installed on SCL ColumnsT-C-SCLCLMCAN17A one-page Canadian Limit States version of the technical bulletin discussing the structural properties of two different surface sides of columns made from structural composite lumber (SCL).Technical Bulletin -
Use of Power-Driven Nails with Simpson Strong-Tie® ConnectorsT-PNEUMATIC12This technical bulletin discusses the use of pneumatically driven nails with Simpson Strong-Tie® connectors. Includes a list of connectors that may be installed with pneumatic nails.Technical Bulletin -
STHD in PFH Wall Bracing AssemblyL-C-STHDPFH417Simpson Strong-Tie® STHD holdowns with Method PFH Wall Bracing on 4-inch Wide Concrete Garage Curb.Engineering Letter -
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Load Tables
Tension Loads for STHD Installations
- Allowable loads are for wind or seismic loading. Nail quantities reflect an increase for duration of load with no further increase allowed. Reduce where other loads govern.
- Concrete shall have a minimum concrete strength, f'c of 2,500 psi.
- 10d common (3" long x 0.148") or 10dx2 1/2" (2 1/2" long x 0.148") nails may be used as a direct replacement for the required nails shown in the table with no load reduction when installed directly over framing or over 1/2" max. structural sheathing
- Use the specified number of nails listed in table or as specified. In many cases, not all nail holes will be filled. Nail strap from the bottom up.
- Deflection at highest allowable loads for install over wood double studs are as follows: Installed on framing: LSTHD8 = 0.089", STHD10 = 0.117" and STHD14 = 0.118". Installed over 1/2" maximum structural sheathing: LSTHD8 = 0.114", STHD10 = 0.146" and STHD14 = 0.164".
- To obtain LRFD values for STHD holdowns, multiply ASD seismic load values by 1.4 and wind load values by 1.6 (1.67 for 2015 IBC).
- Per 2009 and 2012 IBC Section 1613.1, detached one- and two-family dwellings in Seismic Design Category (SDC) C may use "Wind and SDC A&B" allowable loads.
- 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 T-C-SCLCLM for installation on structural composite lumber posts or columns.
- For brick ledge applications, use full loads shown for STHD14 installed in 8" stemwall.
- NAILS: 16d sinker = 0.148" dia. x 3 1/4" long. See other nail sizes and information.
Code Reports
| Part | IAPMO UES ER | ICC-ES ESR | City of Los Angeles | State of Florida |
|---|---|---|---|---|
| LSTHD | See specific model numbers for code listings. | |||
| LSTHD8 | ESR-2920 ESR-2523 | FL13326 | ||
| LSTHD8RJ | ESR-2920 ESR-2523 | FL13326 | ||
| STHD | See specific model numbers for code listings. | |||
| STHD10 | ESR-2920 ESR-2523 | FL13326 | ||
| STHD10RJ | ESR-2920 ESR-2523 | FL13326 | ||
| STHD14 | ESR-2920 ESR-2523 | FL13326 | ||
| STHD14RJ | ESR-2920 ESR-2523 | FL13326 | ||
| STHD8 | ESR-2920 ESR-2523 | FL13326 | ||
| STHD8RJ | ESR-2920 ESR-2523 | FL13326 | ||
ESR-2523 is an Index of many of Simpson Strong-Tie Stamped and Welded Cold-formed Steel Products for Wood or Cold-formed Steel Construction |
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Drawings
| Part | Orthographic | Perspective |
|---|---|---|
| LSTHD | None | |
| LSTHD8 | ||
| LSTHD8RJ | None | None |
| STHD | None | |
| STHD10 | None | |
| STHD10RJ | None | |
| STHD14 | None | |
| STHD14RJ | ||
| STHD8 | None | |
| STHD8RJ | None |
