ASTHD Strap Tie Holdowns — High-Load Uplift Resistance for Earthquake and Hurricane Zones
The ASTHD Strap Tie Holdowns are 12-gauge galvanized steel connectors designed to embed into concrete foundations and nail to shear panel perimeter members, providing structural resistance against uplift loads caused by earthquake and hurricane forces. Engineered for economical, high-load performance, they are a preferred choice among contractors working on wood-framed structures in seismic and high-wind regions. The nail pattern is specifically designed to facilitate nailing to the edges of double 2x members, ensuring proper fastener placement and load transfer. Code listed under ESR-3635, these holdowns meet the requirements for use in IBC-governed construction.
Technical Specifications
| Specification | Details |
|---|---|
| Material | 12ga. galvanized steel |
| Finish Options | G-185 Triple Zinc or Hot-Dip Galvanized (call for availability) |
| Code Listing | ESR-3635 |
| Nail Type | 10d common (3-inch long x 0.148-inch diameter) — may be used with no load reduction |
| Compatible Members | Double 2x members (edges) |
| Application | Embeds into concrete foundations; nails to shear panel perimeter members to resist uplift load from earthquake and hurricane forces |
| ASTHD10 Deflection at Highest Allowable ASD Load | 0.067-inch |
| ASTHD14 Deflection at Highest Allowable ASD Load | 0.084-inch |
| ASTHD10 Max LRFD Capacity | 7700 pounds (with time effect factor of 1.0) |
| ASTHD14 Max LRFD Capacity | 8250 pounds (with time effect factor of 1.0) |
| LRFD Seismic Load Conversion | Multiply seismic ASD loads by 1.4 to obtain LRFD capacities |
| LRFD Wind Load Conversion | Multiply wind ASD loads by 1.6 to obtain LRFD capacities |
| Minimum Center-to-Center Spacing | 3 times the required embedment (Smin = 3 x LE) for holdowns acting in tension simultaneously |
| Mid-Wall End Distance | Based on 1.5 x LE end distance |
| IBC Seismic Design Category Note | Per IBC Section 1613.1, detached one- and two-family dwellings in SDC C and under may use design loads for SDCs A, B |
Available Models — Load and Deflection Data
| Model | Deflection at Highest Allowable ASD Load | Max LRFD Capacity (Time Effect Factor 1.0) |
|---|---|---|
| ASTHD10 | 0.067-inch | 7700 pounds |
| ASTHD14 | 0.084-inch | 8250 pounds |
The ASTHD holdowns deliver an economical high-load solution compared to alternatives, with a nail pattern specifically configured for double 2x member edges to maximize fastener engagement. The availability of both G-185 Triple Zinc and Hot-Dip Galvanized finishes allows contractors to select the appropriate corrosion protection level for their project environment. Larger seat-bearing and designed direct nailing ensure proper installation of all nails, reducing the risk of installation error in the field.
Key Features & Benefits
High-Load Uplift Resistance
With LRFD capacities up to 8250 pounds (ASTHD14) and 7700 pounds (ASTHD10), these holdowns are engineered for demanding seismic and wind uplift applications. High load capacity in a strap tie format gives contractors a reliable, code-compliant solution for shear wall assemblies.
Optimized Nail Pattern for Double 2x Members
The nail pattern is specifically designed to facilitate nailing to the edges of double 2x members, ensuring all fasteners are properly placed for full load transfer. This reduces the chance of missed or improperly driven nails during installation.
No Load Reduction with Standard 10d Common Nails
10d common nails (3-inch long x 0.148-inch diameter) may be used with no load reduction, simplifying fastener selection on the job site. Contractors can use a standard nail without downgrading the published load values.
Larger Seat-Bearing and Direct Nailing Design
The larger seat-bearing area and designed direct nailing geometry promote proper installation of all nails, consistent with best practices for joist hanger and holdown connections. This design feature supports accurate, repeatable field installation.
Dual Finish Options for Corrosion Protection
Available in G-185 Triple Zinc or Hot-Dip Galvanized finishes, the ASTHD accommodates projects with varying exposure and corrosion requirements. Contractors should call for availability of the Hot-Dip Galvanized option.
Code Listed — ESR-3635
Listing under ESR-3635 provides the documentation needed for plan review and inspection approval on IBC-governed projects. The IBC Section 1613.1 provision for SDC C and below further simplifies design for qualifying residential structures.
Common Applications
Shear Wall Holdown at Concrete Foundation
The ASTHD embeds into concrete foundations and connects to shear panel perimeter members, anchoring the wood-framed wall system against uplift forces at the base of the structure.
Seismic Uplift Resistance
Used in Seismic Design Categories where uplift loads from lateral earthquake forces must be transferred from the shear panel into the foundation, the ASTHD provides the required load path continuity.
Hurricane and High-Wind Uplift Resistance
In high-wind regions, the ASTHD resists uplift loads caused by hurricane forces acting on the structure, helping maintain the integrity of the wall-to-foundation connection.
Double 2x Perimeter Member Connections
The nail pattern is optimized for nailing to the edges of double 2x members, making the ASTHD well-suited for shear panel assemblies where double studs or boundary members are used at panel edges.
Compatible Materials
- Concrete foundations (embedment)
- Double 2x lumber members (edge nailing)
- Shear panel perimeter members
- 10d common nails (3-inch long x 0.148-inch diameter)
Product Documents
Frequently Asked Questions
Q: What is the primary application for the ASTHD Strap Tie Holdowns?
A: The ASTHD holdowns embed into concrete foundations and nail to shear panel perimeter members to resist uplift load caused by earthquake and hurricane forces on a structure.
Q: What nail type should be used, and is there a load reduction?
A: 10d common nails (3-inch long x 0.148-inch diameter) may be used with no load reduction.
Q: What are the maximum LRFD capacities for the ASTHD10 and ASTHD14?
A: The ASTHD10 must not exceed 7700 pounds and the ASTHD14 must not exceed 8250 pounds LRFD capacity, with a time effect factor of 1.0.
Q: How do I convert ASD loads to LRFD capacities?
A: Multiply seismic ASD loads by 1.4 and wind ASD loads by 1.6 to obtain LRFD capacities, subject to the maximums stated above.
Q: What finish options are available, and how do I order the Hot-Dip Galvanized version?
A: The ASTHD is available in G-185 Triple Zinc or Hot-Dip Galvanized finishes. Call for availability of the Hot-Dip Galvanized option.
Q: What is the minimum spacing requirement when multiple holdowns are acting in tension simultaneously?
A: The minimum center-to-center spacing is 3 times the required embedment (Smin = 3 x LE) for holdowns acting in tension simultaneously. Mid-wall location is based on 1.5 x LE end distance.