Hurricane strapping & tie down fastener requirements.

What type of fasteners are permitted for use in structural connectors such as joist hangers and steel strapping or hurricane tie-downs?

Hurricane Tie Down or Strapping & Other Framing Connector Fastener Requirements

Question: Can I use screws to install the straps instead of nails

2019/02/01 dave said:

I have to install new hurricane straps to tie the rafters to the top plate and the wall in zone 3 (port orange FL 32129).

Can I use screws to install the straps instead of nails

This question and answer were posted originally at MOBILE HOME STABILIZING SYSTEMS

Illustration of Simpson Strong-Tie's H2.5A Hurricane Tie shown here is for Trusses as illustrated by the company in 2019.

[Click to enlarge any image]

The company describes this product as:

The H2.5A hurricane tie provides a positive connection between rafter/truss and the wall of the structure to resist wind and seismic forces. - Simpson 2022/04/06 cited below. Note that the illustration shows the fastener as an 8d (0.131" x 2 1/2") Nail. More about screw options is given later on this page.

Reply: generally no, but [2022 update) Simpson Strongtie does provide a special fastener screw for many framing connectors

Dave

Your local building inspector might approve construction screws rather than nails to attach hurricane strapping to tie down rafters to a top plate PROVIDED that the screws are properly-selected construction screws of the right size and length.

But probably not, or at least not any screw that is not specifically tested and approved by the manufacturer for that use - as I will explain below.

As a more-general point, never conventional generic hardware screws and do not use drywalls screws where structural connectors specify nails or other special fasteners. .

Why not use screws? After all, in my OPINION, because screws have a greater withdrawal resistance than nails they can be superior in some applications.

However, the risk if construction screws are used in steel connectors such as hurricane tie-downs is that such screws might break under load across the screw diameter even though their screw design resists pulling out of the wood.

Most construction screws are smaller in cross-sectional diameter than the galvanized joist hanger nails designed for use with joist hangers and similar structural steel strapping and tie-downs.

My photos (above & below) illustrates the use of joist hanger nails as specified by Simpson at a job requiring that we strap roof I-joists to the building's structural frame.

Simpson’s instructions for which nail is used for nailing the strapping or tie-down to the framing lumber vary a bit by connector and its application but the most-common is the 8d (0.131" x 2 1/2") Nail.

Shown below is Simpson Strongtie's H1 hurricane tie, for which, in the instructions for the H1 (given below) the company cites two fasteners: an 8d 2 1/2" nail and an 8d 1 1/2" nail.

...

Below is a list of the fasteners specified for the most-commonly-used Simpson Strong Tie Tie Down Connectors and listed as acceptable when this question was posted in 2019, source as cited below.

Below is a 2019 list; be sure to see our update following the list.

• H2.5A Hurricane Tie: 8d (0.131" x 2 1/2") Nail
• H2.5T Hurricane Tie: 8d (0.131" x 2 1/2") Nail
• H10A Hurricane Tie: Blocking Condition connecting truss/rafter and wall: 8d (0.131" x 2 1/2") Nail
• H10A Hurricane Tie: Rafter Condition, connecting rafter to wall top plate: 10d (0.148" x 1 1/2") Nail
• LS Utility Clip/Skewable Angle: 10d x 1 1/2" (0.148" x 1 1/2") Nail
• LSTA Strap Tie used over a ridge-board to strap I-Joists as ridge ties: 10d (0.148" x 3") Nail OR 10d x 1 1/2" (0.148" x 1 1/2") Nail
  For I-joist installation only.
• LTP4/LTP5 Framing Angle Connector - connecting top plate to rim board or blocking, 8d (0.131" x 2 1/2") Nail and 8d x 1 1/2" (0.131" x 1 1/2") Nail
• MST Strap TIe (can be installed with either nails or bolts): 16d (0.162" x 3 1/2") Nail [bolt not specified]
• RBC Roof Boundary Clip: 10d x 1 1/2" (0.148" x 1 1/2") Nail
• RSP Stud Plate Tie: 8d x 1 1/2" (0.131" x 1 1/2") Nail
• SP Stud Plate Tie: (provides uplift resistance): 10d (0.148" x 3") Nail
• SSP Stud Plate Tie: 10d (0.148" x 3") Nail
• TSP Stud Plate Tie (truss to plate): 10d (0.148" x 3") Nail

Really? Nope. Thanks to InspectApedia reader Brian, we have this update: 2022/04/06:

the Simpson Strong-Tie #9 x 1-1/2 in. 1/4-Hex Drive, Strong-Drive SD Connector Screw is now approved by that manufacturer for use with many framing connectors.

And a review of the list of connectors for which Simpson Strongtie approves the use of these connector screws [PDF and link provided below] shows that the 1 1/2" SD connector screw is now (2022) acceptable for Simpson Strongtie's

• H1 Hurricane Tie
• H2A Hurricane Tie
• H2.5A Hurricane Tie
• H3 Hurricane Tie
• H8 Hurricane Tie
• HJ10A Hurricane Tie
• And many other Simpson framing connectors

Watch out: if you cannot show that the screws you use are specifically designed for and rated for steel structural connectors like hurricane tie-downs by the same manufacturer, then the inspector is likely to "fail" your job.

I have not yet found construction screws such as deck screws that were rated for use with steel connectors except for Simpson's Strong-Drive SD connector screws discussed in more-detail below.

Bottom line: when using framing connectors or tie-downs you must use connectors in their intended application, and you must use fasteners that are approved for that use by the manufacturer of the connector you are using.

Your local building department is the final legal authority on building code compliance questions..

The illustration below, excerpted from Simpson StrongTie’s installation instructions for tie-downs, shows only nails, not screws.

Framing Connectors - Hurricane Tie-Downs - Connector Screws or Nails - Instructions

• SIMPSON Strongtie® POCKET GUIDE to FASTENERS [PDF] Simpson Strong-Tie, - retrieved 2022/04/06 original source: https://www.strongtie.com/resources/product-installers-guide/fasteners
  
  Note that this structural fastener guide includes other types of bolts and screws than those discussed here, such as the Titen masonry screw and machine bolts. But it omits the newer Simpson Strong-Tie #9 x 1-1/2 in. 1/4-Hex Drive, Strong-Drive SD Connector Screw discussed on this page.
• SIMPSON Strongtie® H1 HURRICANE TIE - RAFTERS - INSTRUCTIONS [PDF] (2022) Simpson Strong-Tie - retrieved 2022/04/06 original source: https://www.strongtie.com/resources/product-installers-guide/h1-rafter-condition
• SIMPSON Strongtie® H1 HURRICANE TIE - TRUSSES - INSTRUCTIONS [PDF]Simpson Strong-Tie - retrieved 2022/04/06 original source: https://www.strongtie.com/resources/product-installers-guide/h1-truss-condition
• SIMPSON STRONGTIE®, H2.5A HURRICANE TIE INSTALLATION INSTRUCTIONS [PDF] (2022) Simpson Strong-Tie - retrieved 2022/04/06 original source: www.strongtie.com/resources/product-installers-guide/h25a-installation

Above: Simpson Strong-Tie #9 x 1-1/2 in. 1/4-Hex Drive, Strong-Drive SD Connector Screw approved by that manufacturer for use with many framing connectors - those listed in the PDF file given just below.

• SIMPSON® CONNECTORS ALLOWED with SIMPSON #9 x 1-1/2 in. 1/4-Hex Drive, Strong-Drive SD Connector Screw [PDF] - retrieved 2022/04/06 original source: www.strongtie.com/products/fastening-systems/technical-notes/sd-connector-screw-approved-connectors

Other structural fasteners from Simpson Strong-Tie

• SIMPSON Strong-Drive® SDWC TRUSS SCREW INSTRUCTIONS [PDF] Simpson Strong-Tie, - retrieved 2022/04/06 original source: https://www.strongtie.com/resources/product-installers-guide/sdwc-truss-screw-installation
  Excerpt:
  The Strong-Drive SDWC Truss screw provides a stud-to-bottom plate or stud-to-top plate connection as well as fastening trusses and rafters to top plates. The full-threaded shank engages the entire length of the fastener, providing a secure connection.
  
  The SDWC is tested in accordance with ICC-ES AC233 (screw) and AC13 (wall assembly and roof-to-wall assembly) for uplift and lateral loads between wall plates and vertical wall framing and between the top plate and the roof rafters or trusses.
  
  It is code listed under IAPMO-UES ER-262 and meets 2012 and 2015 IRC® and IBC® code requirements for several common wood framing applications.

• SIMPSON Strong-Drive® SDWF FLOOR to FLOOR SCREWS INSTRUCTIONS [PDF] Simpson Strong-Tie, - retrieved 2022/04/06 original source: https://www.strongtie.com/resources/product-installers-guide/sdwf-floor-screw-installation
  Excerpt
  The Strong-Drive SDWF Floor-to-Floor screw is designed to simplify the wind-uplift restraint connection while providing superior performance over the life of the structure.
  
  The unique design of the SDWF enables it to attach upper and lower walls together from the top, spanning the floor system and providing an easy-to-install connection within the continuous uplift load path of the structure.
  
  The innovative Take-Up Washer (TUW) plays a key role in the long-term performance of the SDWF when installed between the screw head and the sole plate of the upper floor.

Other recent Strongtie® Structural Screws

• Simpson 2" SDWS wood screws: In the company's 2022 catalog Simpson also added a 2" SDWS Structural Wood Screw for use in framing connections that in turn use Simpson's "Outdoor Accents" decorative (structural connector) hardware.
• Simpson #12 / # 14 Stainless Steel DWP Structural Screws [PDF] Simpson also provides load-rated DWP Wood SS screws used as structural connectors. These are a type 316 stainless steel wood screw sold in sizes #12 and #14 at lengths from 2 1/2" up to 6".
• Simpson SDWS Framing Screws
• Simpson SDWS Timber SS Screws (Interior & exterior grades)
• The company presently (2022) manufactures more than 600 types of framing and wood and flooring and other special-purpose screws including for use as structural fasteners, deck fasteners, etc.

 

 

Reader Comments & Q&A

On 2022-04-06 by Inspectapedia Com Moderator (mod) - This Strong-Drive SD connector screw now approved for use with many Simpson Strong-Tie framing connectors

@Brian,

Thank you for the comment and the reference to the Simpson Strong-Tie #9 x 1-1/2 in. 1/4-Hex Drive, Strong-Drive® SD Connector Screw .

That's a valuable update for our article on this topic and we appreciate that you took time to bring it to our attention. Working together makes us smarter.

According to the manufacturer:

The Strong-Drive SD Connector screw is specifically designed to replace nails in certain Simpson Strong-Tie connectors and is the only screw approved for that application. The load-rated SD screw has been tested and approved for use in many popular Simpson Strong-Tie products.

In certain applications screws are easier and more convenient to install than nails, and the single-fastener load values achieved by the SD screw exceed those of typical 10d common or 16d common nails.

In addition, the galvanized coating makes the SD screw ideal for interior and most exterior conditions.

Note that the company says "certain Simpson Strong-Tie connectors", it does not say that these screws are suitable for all framing connectors.

Details from the company include:

Specifically designed to replace nails in certain Simpson Strong-Tie connectors and is the only screw approved for that application. The #9 and #10 SD screws replace 10d and 16d nails, respectively.

The single-fastener load capacity of the #9 SD screw exceeds the capacity of a 10d common nail, while the single-fastener load capacity of the #10 SD screw exceeds that of the 16d common nail.

Tested and approved for use in many of our most popular connectors for both interior and exterior applications.

Ideal for use in connector applications where more control is desired or using a hammer is inconvenient.

1/4" hex head with 0.37"-dia. integrated washer is stamped with the Simpson Strong-Tie "≠" sign and the fastener size for easy identification after installation.

- source: Simpson Strong-Tie, retrieved 2022/04/06, original source: https://www.strongtie.com/strongdrive_exteriorwoodscrews/sd_screw/p/strong-drive-sd-connector-screw

You will see that the list of framing connectors for which the #9 x 1-1/2 in. 1/4-Hex Drive, Strong-Drive SD Connector Screw is approved is pretty long. We provide a copy of the current list of connectors accepting the Strong-Tie #9 x 1-1/2 in. 1/4-Hex Drive, Strong-Drive® SD Connector Screw above on this page.

On 2022-04-05 by Brian - #9 Screws rated / approved for use with Simpson Strong-Tie hurricane tie-down straps.

#9 x 1-1/2 in. 1/4-Hex Drive, Strong-Drive SD Connector Screw

These are rated for Simpson strong tie straps

On 2020-10-07 by (mod)

Glad to assist. Don't hesitate to post questions or content suggestions
thanks

On 2020-10-07 by Daniel

Great Article!

I'm building a Gazebo, and I'm drinking in as much as I can about framing, fasteners, and strong ties. Very Informative, and I'm glad I found this website!

...

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