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General Notes for Wood Construction Connectors

Technical & Installation Notes


Simpson Strong-Tie Company Inc. structural connectors, anchors, and other products are designed and tested to provide specified design loads. To obtain optimal performance from Simpson Strong-Tie products and achieve maximal allowable design load, the products must be properly installed and used in accordance with the corrosion information, installation instructions and design limits provided by Simpson Strong-Tie. To ensure proper installation and use, designers and installers must carefully read the following General Notes, General Instructions for the Installer, General Instructions for the Designer and Corrosion Information, as well as consult the applicable catalog pages for specific product installation instructions and notes.

Proper product installation requires careful attention to all notes and instructions, including these basic rules:

  1. Be familiar with the application and correct use of the connector.
  2. Read and follow all instructions and warnings on our website, in this and any other applicable catalog, in the Installer’s Pocket Guide and all other Simpson Strong-Tie publications. If any instructions or warnings are unclear, do not use the product and contact Simpson Strong-Tie.
  3. Install all required fasteners per installation instructions provided by Simpson Strong-Tie: (a) use proper fastener type; (b) use proper fastener quantity; (c) fill all fastener holes; (d) do not overdrive or underdrive nails, including when using powder nailers; and (e) ensure screws are completely driven.
  4. Only bend products that are specifically designed to be bent. For those products that require bending (such as strap-type holdowns, straight-end twist straps, etc.), do not bend more than one full cycle.
  1. Cut joists to the correct length, do not "short-cut." The gap between the end of the joist and the header material should be no greater than 1/8″ unless otherwise noted.
  2. Wear head, skin, eye and ear protection when installing the products or visiting a jobsite.

Failure to follow fully all of the notes and instructions provided by Simpson Strong-Tie may result in improper installation of products. Improperly installed products may not perform to the specifications set forth in this catalog and may reduce a structure’s ability to resist the movement, stress, and loading that occurs from gravity loads as well as impact events such as earthquakes and high-velocity winds.

Simpson Strong-Tie provides no warranty for any products that have been modified, improperly installed or not used in accordance with the information set forth in this catalog or on our website.

Important Information

In addition to following the basic rules provided above as well as all notes, warnings and instructions provided in the catalog, installers, designers, engineers and consumers must consult the Simpson Strong-Tie website at strongtie.com each time a product is used to obtain additional design and installation information.

Simpson Strong-Tie Limited Warranty

For the Limited Warranty that applies to Simpson Strong-Tie products, please consult Simpson Strong-Tie Limited Warranty.

Terms and Conditions of Sale

Product Use

Products in this catalog are designed and manufactured for the specific purposes shown, and should not be used with other connectors not approved by a qualified licensed/certified building design professional, a licensed professional engineer or licensed architect (“designer”). You should review our website and consult a qualified designer familiar with all applicable building codes each time you use a Simpson Strong‑Tie product.


Any designer or other person who modifies any products, changes any installation procedures or designs any non-catalog products for fabrication by Simpson Strong-Tie Company Inc. shall, regardless of specific instructions to the user, indemnify, defend, and hold harmless Simpson Strong-Tie Company Inc. for any and all claimed loss or damage occasioned in whole or in part by such products.

Non-Catalog and Modified Products

Modifications to products or changes in installation procedures should only be made by a qualified professional designer. The performance of such modified products or altered installation procedures is the sole responsibility of the designer. Any person modifying Simpson Strong-Tie products must provide the installer with specific instructions on the modified products’ specifications, installation and use.

Consult Simpson Strong-Tie Company Inc. for applications for which there is no catalog product, or for connectors for use in hostile environments, with excessive wood shrinkage, or with abnormal loading or erection requirements.

Non-catalog products must be designed by a qualified designer and will be fabricated by Simpson Strong-Tie in accordance with customer specifications.

Any modified, special order or non-catalog products, or any products that are not installed strictly in accordance with Simpson Strong-Tie installation procedures, are provided "AS IS" and without any representation or warranty of any kind.

General Notes

These general notes are provided to ensure proper installation of Simpson Strong-Tie products and must be followed fully.

  1. Simpson Strong-Tie Company Inc. reserves the right to change specifications, designs and models without notice or liability for such changes. Review our website each time you use our products.
  2. Steel used for each Simpson Strong-Tie product is individually selected based on the product’s steel specifications, including strength, thickness, formability, finish and weldability. Contact Simpson Strong-Tie for steel information on specific products.
  3. Unless otherwise noted, dimensions are in inches, loads are in pounds.
  4. Unless otherwise noted, welds, screws, bolts and nails may not be combined to achieve highest load value. 0.131" x 2 1/2", 0.148" x 3" and 0.162" x 3 1/2" specify common nails that meet the requirements of ASTM F1667. When a shorter nail is specified, it will be noted (for example 0.131" x 1 1/2"). Refer to Simpson Strong‑Tie Nailing Guide, NDS (National Design Specification) and ASTM F1667 (American Society of Testing and Materials) for more nail information.
  5. Do not overload. Do not exceed catalog allowable loads.
  6. Unless otherwise noted, allowable loads are for Douglas fir–larch under continuously dry conditions. Allowable loads for other species or conditions must be adjusted according to the code. This chart shows specific gravity and perpendicular-to-grain compression capacities for the different wood species.

  7. Species Fc | Specific Gravity
    Douglas Fir–Larch (DF) 625 psi 0.50
    Southern Pine (SP) 565 psi 0.55
    Spruce-Pine-Fir (SPF) 425 psi 0.42
    Spruce-Pine-Fir South (SPF-S) 335 psi 0.36
    Hem Fir (HF) 405 psi 0.43
    Glulam 650 psi 0.50
    LVL (DF/SP) 750 psi 0.50
    LSL (E=1.3x106) 680 psi 0.50
    LSL (E>1.5x106) 880 psi 0.50
    Parallam® PSL 625 psi 0.50
    Western Cedar 425 psi 0.36
  8. Simpson Strong-Tie Company Inc. will manufacture non-catalog products provided prior approval is obtained and an engineering drawing is included with the order. Steel specified on the drawings as 1⁄8", 3⁄16" and 1⁄4" will be 11 ga. (0.120"), 7 ga. (0.179") and 3 ga. (0.239"), respectively. The minimum yield and tensile strengths are 33 ksi and 52 ksi, respectively.
  9. All references to bolts are for structural quality through bolts (not lag screws or carriage bolts) equal to or better than ASTM Standard A307, Grade A. Nuts shall be ASTM A563, Grade A or better, unless noted otherwise.
  10. Unless otherwise noted, bending steel in the field may cause fractures at the bend line. Fractured steel will not carry load and must be replaced.
  11. A fastener that splits the wood will not take the design load. Evaluate splits to determine if the connection will perform as required. Dry wood may split more easily and should be evaluated as required. If wood tends to split, consider pre-boring holes with diameters not exceeding 0.75 of the nail diameter (2015/ 2018 NDS Use a 5⁄32" bit for Strong-Drive® SDS Heavy-Duty Connector screws and a 3/32" bit for Strong-Drive SD9/SD10 Connector screws.
  12. Wood shrinks and expands as it loses and gains moisture, particularly perpendicular to its grain. Take wood shrinkage into account when designing and installing connections. Simpson Strong-Tie manufactures products to fit common dry-lumber dimensions. If you need a connector with dimensions other than those listed in this catalog, Simpson Strong-Tie may be able to vary connector dimensions; contact Simpson Strong-Tie. The effects of wood shrinkage are increased in multiple lumber connections, such as floor-to-floor installations. This may result in the vertical rod nuts becoming loose, requiring post-installation tightening. (Reference ICC-ES ESR-2320 for information on Take-Up Devices.)
  13. Top-flange hangers may cause unevenness. Possible remedies should be evaluated by a professional and include using a face-mount hanger, and routering the beam or cutting the subfloor to accommodate the top flange thickness.
  14. Built-up lumber (multiple plies) must be fastened together to act as one unit to resist the applied load (fastening of the members together does not include the connector fasteners). This must be determined by the designer.
  15. Some model configurations may differ from those shown in this catalog. Contact Simpson Strong-Tie for details.
  16. Hanger Options Matrix – some combinations of hanger options are not available. In some cases, combinations of these options may not be installable. Horizontal loads induced by sloped joists must be resisted by other members in the structural system.
  17. A qualified designer must always evaluate each connection, including carried and carrying member limitations, before specifying the product. Fill all fastener holes with fastener types specified in the tables, unless otherwise noted. Hanger configurations, height and fastener schedules may vary from the tables depending on joist size, skew and slope. See the allowable table load for the non-modified hanger, and adjust as indicated. Gauge may vary from that specified depending on the manufacturing process used. Simpson Strong-Tie will calculate the net height for a sloped seat. The customer must provide the H1 joist height before slope.
  18. Truss plates shown are the responsibility of the truss designer.
  19. Do not weld products listed in this catalog unless this publication specifically identifies a product as acceptable for welding, or unless specific approval for welding is provided in writing by Simpson Strong-Tie. Some steels have poor weldability and a tendency to crack when welded. Cracked steel will not carry load and must be replaced. See Simpson Strong-Tie Hanger Options Matrix and Hanger Option General Notes for hangers that may be welded.
  20. Unless noted otherwise, all references to standard-cut washers refer to Type A plain washers (W) conforming to the dimensions shown in ASME B18.22.1 for the appropriate rod size in accordance with 2015/ 2018 NDS Appendix L. Some products require SAE narrow washers (N) to fit in a tight space and are noted accordingly.
  21. To achieve tabulated values for embedded concrete/masonry products, full consolidation of concrete or grout is required whether mounted to the form prior to the pour or wet set.

Wood Construction Connectors General Instructions for the Installer

Download the General Instructions for the Installer for your drawings.

These general instructions for the installer are provided to ensure proper selection and installation of Simpson Strong-Tie Company Inc. products and must be followed carefully. These general instructions are in addition to the specific installation instructions and notes provided for each particular product, all of which should be consulted prior to and during installation of Simpson Strong-Tie Company Inc. products.

  1. All specified fasteners must be installed according to the instructions in this catalog. Incorrect fastener quantity, size, placement, type, material, or finish may cause the connection to fail. Prior to using a particular fastener, please consult Connector Fastener Types.
    • Larger diameter fasteners may be substituted for smaller diameter fasteners in connectors provided the larger fastener does not cause splitting in the wood member and the connector holes are not enlarged.
    • Simpson Strong-Tie® Strong Drive® SD Connector screws are available for use with our connectors. They are designed to replace nails in certain products. See Connectors Approved for Use with the Strong-Drive® SD Structural-Connector Screw for more information. Screws not manufactured by Simpson Strong-Tie are not supported in our products.
  2. Fill all fastener holes as specified in the installation instructions for that product. Refer to the Simpson Strong-Tie Fastener Guide for the requirements of the various shaped fastener holes.
  3. Do not overdrive nails. Overdriven nails reduce shear capacity. See Over-Driven Nails in Connectors and Straps for additional information.
  4. Products shall be installed for the use specified. Use the materials specified in the installation instructions. Substitution of or failure to use specified materials may cause the connection to fail. Do not alter installation procedures from those set forth in this catalog. See Terms and Conditions of Sale.
  5. Do not add fastener holes or otherwise modify Simpson Strong-Tie Company Inc. products. The performance of modified products may be substantially weakened. Simpson Strong-Tie will not warrant or guarantee the performance of such modified products.
  6. The proper use of certain products requires that the product be bent. For those products, installers must not bend the product more than one time (one full cycle).
  7. Bolt holes shall be at least a minimum of 1/32" and no more than a maximum of 1/16" larger than the bolt diameter (per the 2015/ 2018 NDS, Section and AISI S100, Table J3 if applicable).
  8. Install all specified fasteners before loading the connection.
  9. Some hardened fasteners may have premature failure if exposed to moisture. These fasteners are recommended to be used in dry interior applications.
  10. Use proper safety equipment.
  11. Welding galvanized steel may produce harmful fumes; follow proper welding procedures and safety precautions. Welding should be in accordance with A.W.S. (American Welding Society) standards. Unless otherwise noted, Simpson Strong-Tie connectors cannot be welded.
  12. Pneumatic or power-actuated fasteners may deflect and injure the operator or others. Pneumatic nail tools may be used to install connectors, provided the correct quantity and type of nails (length and diameter) are properly installed in the nail holes. Connectors with tool embossments or tools with nail hole-locating mechanisms should be used. CSHP coiled strap works with several manufacturers’ full round-head pneumatic framing tools. Find additional information on the CSHP coiled strap. Follow the manufacturer’s instructions and use the appropriate safety equipment. Contact Simpson Strong-Tie. Power-actuated fasteners should not be used to install connectors, unless noted otherwise. Reference pages 163 and 165 of the Wood Construction Connectors Catalog.
  13. Joist shall bear completely on the connector seat, and the gap between the joist end and the header shall not exceed 1/8" per ICC-ES AC13, ASTM D1761 and ASTM D7147 test standards (unless specifically noted otherwise).
  14. Fasteners are permitted to be installed through metal truss plates when approved by the Truss Designer in accordance with ANSI/TPI 1-2014, Section and 8.9.2. Installation of Simpson Strong-Tie Strong-Drive SDS Heavy-Duty Connector screws through metal connector plates requires the plates to be pre-drilled using a maximum of a 5/32" bit. Do not drive nails through the truss plate on the opposite side of single-ply trusses which could force the plate off the truss.
  15. Nuts shall be installed such that the end of the threaded rod or bolt is at least flush with the top of the nut.
  16. When installing hurricane ties on the inside of the wall, special considerations must be taken to prevent condensation on the inside of the completed structure in cold climates.
  17. Unless otherwise noted, connectors shown in this catalog have been designed to be installed at the time the framing members are installed. Contact Simpson Strong-Tie for retrofit suitability of specific connectors including those manufactured in accordance with the hanger options section.

General Connector Installation

Top-Flange Hangers

Flush Framing Example
Flush Framing

Top flange configuration and thickness of top flange need to be considered for flush frame conditions.

Hanger Over Spread
Hanger Over-Spread

If the hanger is over-spread, it can raise the I-joist above the header and may cause uneven surfaces and squeaky floors. The ITS and IUS with up to 1/4" overspread (both sides combined) will not result in reduced download. It will reduce allowable uplift load.

Hanger Not Plumb
Hanger Not Plumb

A hanger “kicked-out” from the header can cause uneven surfaces and squeaky floors.

Prevent Rotation

Hangers provide some joist rotation resistance; however, additional lateral restraint may be required for deep joists.

No Rotation Resistance
No Rotation Resistance

Lack of web stiffeners combined with short hanger allows unwanted rotation.

Rotation Prevented Example 1
Rotation Prevented by Web Stiffeners or Solid Joist and Hanger Height

Hanger height should be at least 60% of the joist height.

Rotation Prevented Example 2
Rotation Prevented by Web Stiffeners or Solid Joist and Clips or Blocking

If hanger height is less than 60% of the joist height, add clips or blocking near the top.

Rotation Prevented Example 3
Rotation Prevented by Lateral Flange Support

Sides of hanger laterally support the top flange of the I-joist.
No web stiffeners required.

Wood Nailers

Correct Attachment
Correct Attachment
Nailer Too Wide
Nailer Too Wide

The loading may cause cross-grain bending. As a general rule, the maximum allowable overhang is 1/4", depending on nailer thickness.

Nailer Too Narrow
Nailer Too Narrow

Nailer should be full width.

Nailer Too Thin
Nailer Too Thin

Or the wrong hanger for the application.

Toe Nailing

Toe Nailing

Toe nailing causes squeaks and improper hanger installations. Do not toe nail I-joists before installing top-flange or facemount hangers.

Positive Angle Nailing

Correct Nailing
Correct Nailing Approx. 45° Angle
Nail Too Long
Nail Too Long
Nail at Wrong Angle
Nail at Wrong Angle

Other Applications

Sloped Joists

For sloped joists up to 1/4:12, there is no reduction. For slopes greater than 1/4:12, see individual product pages or refer to technical bulletin T-C-SLOPEJST.

Multiple Joists

Multiple joists should be adequately connected together to act as one unit.


Use the correct nails. Wood may split if the nails are too large. Hanger nails into flanges should not exceed 0.148" x 1 1/2". Nails into web stiffeners should not exceed 0.162" diameter.

Eccentrically Loaded I-Joists

Supporting a top-flange hanger may require bottom flange restraining straps, blocking or directly-applied ceiling systems to prevent rotation at the hanger location.

Skewed Joists

Joists may be skewed up to 2 1/2° in a non-skewed hanger without any load reduction. Refer to individual hanger descriptions for information allowing any further skew applications.

Notching Joists

Notching of joists/rafters (or kerf cutting) to accommodate sloped conditions in standard (nonsloped) hangers is not recommended and can lead to premature splitting.

Do Not Notch Joist
Do Not Notch Joist
I-Joist As a Header Installation

When face-mount hangers are attached to I-joist headers, backer blocks must be installed to provide a nailing surface for the hanger nails. The backer blocks should be installed on both sides of the web and attached together with a minimum of (10) 0.148" x 3" nails. The hanger nails should extend through the web. Contact the I-Joist manufacturer for additional design considerations.

Face Mount Hanger
Face-Mount Hanger

When top-flange hangers are attached to I-joist headers, a backer block must be installed to prevent the top flange from rotating under load. The backer blocks should be installed with a minimum of (10) 0.148" x 3" nails clinched. Check with the joist manufacturer for additional design considerations.

Top Flange Hanger
Top-Flange Hanger

Wood Construction Connectors General Instructions for the Designer

These general instructions for the designer are provided to ensure proper selection and installation of Simpson Strong-Tie Company Inc. products and must be followed carefully. These general instructions are in addition to the specific design and installation instructions and notes provided for each particular product, all of which should be consulted prior to and during the design process.

  1. The term “designer” used throughout this catalog is intended to mean a licensed/certified building design professional, a licensed professional engineer, or a licensed architect.
  2. All connected members and related elements shall be designed by the designer.
  3. All installations should be designed only in accordance with the allowable load values set forth in this catalog.
  4. See page 10 of the Wood Construction Connectors Catalog for allowable load information.
  5. See page 267 of the Wood Construction Connectors Catalog for connections with simultaneous loads.
  6. Loads are based on the 2015/ 2018 NDS and AISI S100 if applicable, unless otherwise specified. Other code agencies may use different allowable loads.
  7. Unless otherwise noted, loads include Load Duration, Group Action and Toe-Nail factors from the NDS as applicable. The application of additional adjustment factors shall be by the designer. Duration of load adjustments as specified by the code are as follows:

    "PERMANENT" — 90% of the design load.

    "FLOOR" and "DOWN" (100) — no increase for duration of load.

    "SNOW" (115) — 115% of design load for two month duration of load.

    "ROOF LOAD" (125) — 125% of design load for seven day duration of load.

    "EARTHQUAKE / WIND" (160) — 160% of design load for earthquake/wind loading.

  8. Unless otherwise noted, wood shear is not considered in the loads given; reduce allowable loads when wood shear is limiting.
  9. Simpson Strong-Tie strongly recommends the following addition to construction drawings and specifications: “Simpson Strong-Tie® connectors are specifically required to meet the structural calculations of plan. Before substituting another brand, confirm load capacity based on reliable published testing data or calculations. The Engineer/Designer of Record should evaluate and give written approval for substitution prior to installation.”
  1. Verify that the dimensions of the supporting member are sufficient to receive the specified fasteners, and develop the top flange bearing length.
  2. Some catalog illustrations show connections that could cause cross-grain tension or bending of the wood during loading if not sufficiently reinforced. In this case, mechanical reinforcement should be considered.
  3. The allowable loads published in this catalog are for use when utilizing the traditional Allowable Stress Design methodology. A method for using Load and Resistance Factor Design (LRF D) for wood has been published in ASTM D5457. A method for using LRF D for cold-formed steel has also been published in the AISI S100-16. When designing with LRF D, reference lateral resistances must be used. Contact Simpson Strong-Tie for reference lateral resistances of products listed in this catalog. For more information, refer to the 2015/2018 NDS Appendix N, which contains a conversion procedure that can be used to derive LRF D capacities.
  4. For joist hangers, Simpson Strong-Tie recommends the hanger height shall be at least 60% of joist height for stability against rotation while under construction prior to sheathing install.
  5. For cold-formed steel applications, as a minimum all screws must comply with Society of Automotive Engineers (SAE) Standard J78, Steel Self-Drilling/Tapping Screws, and must have a Type II coating in accordance with ASTM B 633, Electrodeposited Coatings of Zinc on Iron and Steel. Screw strength shall be calculated in accordance with AISI S100 Section J4, if applicable, or shall be based on the manufacturer’s design capacity determined from testing.
  6. Local and/or regional building codes may require meeting special conditions. Building codes often require special inspection of anchors installed in concrete and masonry. For compliance with these requirements, it is necessary to contact the local and/ or regional building authority. Except where mandated by code, Simpson Strong-Tie products do not require special inspection.
  7. Throughout the catalog there are installation drawings showing the load transfer from one element in the structure to another. Additional connections may be required to safely transfer the loads through the structure. It is the designer’s responsibility to specify and detail all necessary connections to ensure that a continuous load path is provided as required by the building code.
  8. Top flange hanger allowable loads are typically based on testing with solid headers. Load reductions may apply when using headers comprised of multiple plies of dimensioned lumber or SCL. See technical bulletin T‑C‑MPLYHEADR at strongtie.com for more information.
  9. For connections involving members with different specific gravities, use the allowable load corresponding to the lowest specific gravity in the connection, unless noted otherwise.