Structural connectors, fasteners, bolts, nails, joist hangers, rafter ties etc.: this article explains the proper selection and installation of structural connectors, brackets & tie plates used to connect deck or porch framing and support members.

USP connectors such as joist hangers, joist angles, joist supports, stud shoes, skew hangers, and face mount hangers used for connecting these hangers and connectors are described, their uses explained, and their applications and specifications linked.

Both galvanized steel and stainless steel joist hangers, connectors, & brackets may be applied.

Choose the Correct Bolts or Fasteners for Wood Structural Framing Connections - Decks & Porches

This article includes excerpts or adaptations from Best Practices Guide to Residential Construction (Steve Bliss, J Wiley & Sons) , by Steven Bliss, courtesy of Wiley & Sons.

Also see our BOOK REVIEW of that book.

Our page top photo shows a hybrid deck structure that encompasses a boat. No fasteners were found securing the boat to the deck however.

At minimum, all structural hardware for decks should be hot-dipped galvanized steel. For the best protection, use stainless steel (see “Joist Hangers and Connectors,” below).

At connections carrying structural loads, such as deck ledgers or railing posts, use through-bolts or lag screws.

Through-bolts are stronger 

and should be used where possible. For the heaviest connections on a deck, such as where ledgers attach to the house or to posts, use 1/2-inch bolts or lags.

Place large washers under the heads 

of lags and at both ends of through-bolts. Re tighten bolts and lags after the first year and check periodically for tightness.

Machine-Threaded Bolts Used for Deck Construction

Where both sides of the joint are accessible, bolts offer the strongest connections. Drill pilot holes 1/32 to 1/16 inch larger than the diameter of the bolt so it will slide through easily.

After drilling, saturate the hole with preservative. Use large washers under both the head and nut. Re tighten after the first year, since the wood may have shrunk.

The damaged, over-nailed wood framing shown in our photo is discussed

at TOE NAILED FRAMING CONNECTIONS.

Lag Bolts Used for Deck Construction

For lag bolted deck connections,

drill a full-diameter pilot hole for the unthreaded portion and a smaller hole (65 to 75% of the lag’s diameter) for the threaded portion. So, for example, a 1/2-inch lag would get a 5/16-inch pilot hole for the threaded portion; a 3/8-inch diameter lag would get a 1/4-inch diameter pilot hole.

After drilling, saturate the pilot hole with wood preservative. It is also important that at least half the length of the lag is threaded into solid wood.

For example, driving a 5-inch lag through a 4x4 post into a 2x joist will produce a weak connection with only 1 1/2 inches of anchoring. Instead, the lag screw should go through the 2x and be threaded into the thicker 4x4. Use a large washer under the head, and re tighten after the first year in case materials have shrunk.

Joist Hangers and Steel Connectors Used for Deck Construction

At a minimum, use hot-dipped galvanized hardware. With pressuretreated wood, hot-dipped galvanized steel should conform to ASTM A153 (for fasteners) or ASTM A653, G185 (for connectors).

Stainless steel offers the best protection. Type 304 or higher stainless steel is recommended for very wet environments such as poolside decks; or Type 326 for exposure to salt or saltwater.

Watch out: Also, do not mix metals: Use stainless-steel fasteners with stainless-steel connectors and galvanized fasteners with galvanized connectors.

Suppliers of Joist, Post & Beam Hangers & Connectors & the Nails or Fasteners used With Them

Stainless steel or galvanized steel joist hangers, connectors and similar products are produced by Simpson Strong Tie, Incom, Schuler Manufacturing, State Metals, Daytona Bolt & Nut, Hutchinson, Cleveland Steel, U.S. Lumber, Hohmann & Barnard, and Direct Tools & Fasteners as well as Paslode, Grip Rite joist hanger nails and other specialty nails.

• Cleveland Steel Structural Fasteners, 26001 Richmond Rd., Bedford Heights, OH 44146,| Phone: 216.464.9400, Fax: 216.464.9404, E-mail: info@clevelandsteel.com, Website: http://clevelandsteel.thomasnet.com/category/construction-hardware-division?
• Daytona Bolt & Nut, 815 N. Beach Street, P.O. Box 1391, Daytona, FL 32114, P: 386-255-0248, F: 386-257-5985, E-mail:Daytona@DaytonaBolt.com
• Schuler Mfg. & Equip. Co. Inc., 63724 Richland Road, Griswold, Iowa 51535, Tel: (712) 774-2228 Website: http://www.schulermfg.net/
• Simpson Strong Tie®, Tel:1-800-999-5099, Website: http://www.strongtie.com/
• Incom Distributor Supply, PO Box 868, Fort Wayne IN 46801, Tel: 260-748, 5469, Website: http://shop.incomsupply.com/shop/, "... a growing nationwide network of over 500 Commercial Industrial Distributors" Incom Inc, 73-5600 Kauhola St Ste C, Kailua Kona, HI 96740, Tel: (808) 329-1311
• USP Structural Connectors®, Tel: 1-800-328-5934, Email: uspcustomerservice@mii.com, Website: http://www.uspconnectors.com/

-- Adapted with permission from Best Practices Guide to Residential Construction (Steve Bliss, J Wiley & Sons) .
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Reader Q&A - also see RECOMMENDED ARTICLES & FAQs

orries that drilled bolt holes in wood promote rot

Through bolt bolt vs. lag screw. While a through bolt application is stronger than a lag screw in terms of overall strength. It should be noted that using a through bolt where a level bolt hole is drilled through wood

In exterior applications water will seep into and collect in the bolt hole accelerating water damage and rot at the connection point.

Using a proper size lag screw for the intended load, along with the proper hole drilling procedure will eliminate the area where water collects around the lag screw connector, reducing the water damage and wood rot factor significantly. - On 2020-05-28 by Darrell W

Reply bydanjoefriedman (mod): research on structural wood rot due to drilled holes for bolts

Thank you, Darrell, for making a very interesting point on lag screws vs. through bolts for structural connectors.

Even a quick scan of research on this topic suggests that your point is more than just speculative opinion that rot at through-bolt holes can be a problem (Ho 2007).

If you can add any expert source or research citations to this topic that'd be great.

What I found in searching for research on rot damage at through-bolt framing or timber connections (+ nailing) is given below.

• Anthony, Ronald W. "Examination of connections and deterioration in timber structures using digital radioscopy." In Forensic Engineering (2003), pp. 320-328. 2003.
• Ho, Vickie WK, Mahesh D. Pandey, and S. Bedi. "Effects of surface decay on remaining strength of transmission-line wood cross-arms." IEEE transactions on power delivery 23, no. 1 (2007): 419-424.
  Abstract:
  
  This paper develops a model that correlates the amount of surface deterioration to the remaining strength of rectangular Douglas-fir cross-arms used in a 115-kV transmission line. One challenge that utility companies face today is to develop effective strategies to replace cross-arms that are potentially detrimental to the transmission-line system.
  
  In service cross-arms are continuously exposed to the environment and experience wide ranging temperatures and moisture conditions. Furthermore, rainwater entrapment on surface and bolt holes causes rotting and decay of wood, resulting in gradual loss of strength.
  
  The evaluation of the remaining strength of in service cross-arms is complicated further by a large variability associated with the wood microstructure, the decay process, defects, and environmental conditions.
  
  To understand the effects of surface decay on the strength of wood cross-arms, an image-processing technique is employed to accurately quantify the amount of deterioration and examine the effects of decay location.
  
  Full-scale bending tests are used to assess the remaining strength.
  
  Statistical models have shown that surface decay, depending on its location, has a direct linear relationship with the strength loss for wood cross-arms in bending.
  
  Excerpt:
  
  Furthermore, rainwater entrapment on surface and bolt holes causes rotting and decay of wood, resulting in gradual loss of strength
• Loferski, Joseph, and P. E. Frank Woeste. "Strong rail-post connections for wooden decks." Journal of Light Construction 23, no. 5: 65-71.
• Pandey, M. D., V. Ho, F. McCarthy, and S. B. Woodward. "Experimental evaluation of remaining strength of crossarms in Gulfport transmission line wood structures." Canadian Journal of Civil Engineering 37, no. 4 (2010): 638-647.
• Pandey, M. D., V. Ho, S. Bedi, and S. B. Woodward. "Development of a condition assessment model for transmission line in-service wood crossarms." Canadian Journal of Civil Engineering 32, no. 3 (2005): 480-489.
• Sawata, Kei, and Yoshihisa Sasaki. "Lateral strength of nailed timber connections with decay." Journal of wood science 64, no. 5 (2018): 601-611.

OK to use galvanized wood deck screws in joist hangers?

I'm using galvanize deck screws to hang joise hangers for 2x8 three feet long. Instead of nails is that ok ? - On 2017-11-14 by Larry Jacob

Reply by mod: if the screws you are using are structural screws and specifically say they're intended for use with joist hangers that's fine. I worry that they're not.

Structural screws that are intended for use with joist hangers are labeled for that purpose and are shorter and heavier than wood screws used to secure deck boards to a joist.

What are the right bolts to use to connect metal post base to concrete piers?

? on concrete anchors is in Richmond, VA. Posts (about 4 feet) are sold at Home Depot, made by Barrette. Posts are metal with a metal base with 4 holes at 3/8 inch. Manufacturer's instructions says to "Follow masonry anchor installation instructions." but they do not provide them.

Their instructions for mounting on wood deck says to use 5/16 diameter grade 5 bolts and nuts galvanized per ASTM F2329. Metal post has à vinyl sleeve that covers the top of any bolts/anchors that are used.

Local building inspector office - I have asked 3 different employees and they each have given me a12 page handout for wood decks and handrails.

When I tell them "this is concrete & metal" they say "just go by our handout" = it says 1/2 botls that are 4 inches long.

These bolts are too big to insert in the metal posts. (grrr!) On 2015-08-25 by DavidElswick

Reply by danjoefriedman (mod): use L-bolts or expanding anchor bolts into concrete pier top to hold steel post base bracket

David

I was born in Richmond so I know the weather - not so much freezing but enough to want to avoid frost damage to the connectors. Look into a drill and epoxy fill lag bolt anchor system from your local hardware store.

Yes the people you are asking are ducking and weaving. Just sayin

Typically the installer uses a wet set anchor "L" bolt put into the concrete pier to anchor the post bracket to the pier - such as the Wet Set Anchor L-Bolts shown below from Midwest Perma Column

If you need to install steel post bracket bolts into a concrete pier that has already been cast and set, you'll drill into the base and use an expanding anchor type bolt instead. In that case I add sealant to the hole before inserting the expanding bolt lead anchors so that I minimize the risk of future frost damage to the pier top.

On 2015-08-24 by Size screws 4 post on concrete porch?

Need to mount metal posts to a concrete porch (over 55 years old) and a new concrete porch with a brick veneer wall (where posts will be mounted). New metal posts have a 3/8 inch hole but no instructions on how to anchor. What size of lag screw should I use & what size of lag shield? How long should the lag screw be?

Have asked my local building inspection department 3 times, and each time they give me a handout for wood posts on a wood deck which calls for 1/2 * 4 inch screws.

Reply by danjoefriedman (mod)

Charming to let you figure out the critical point, right, including not just what fasteners, but also what connection will be strong enough to be safe. Not knowing just what metal post system you are installing I'm not sure what to prescribe.

Typically we secure things to concrete using either lead anchors and galvanized 3/8" lag screws or we might try using tapcons (R). But watch out: especially in a freezing climate we need to worry about water getting into those screw openings followed by freeze damage leading to slab damage and to unsafe railings.

There are expoxy systems used to mount exterior bolts in concrete surfaces that may avoid that trouble.

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Continue reading at HURRICANE TIE DOWN CONNECTORS & FASTENERS or select a topic from the closely-related articles below, or see the complete ARTICLE INDEX.

Or see these

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• CONNECTORS, FASTENERS, TIES
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• DECK FRAMING TABLES, SPANS
• FRAMING DAMAGE, INSPECTION, REPAIR - home
• FRAMING FASTENERS, NAILS, SCREWS - best construction practices.
• FRAMING CONNECTORS & JOIST HANGERS - best construction practices.
• HURRICANE TIE DOWN CONNECTORS & FASTENERS - are screws ok to use instead of nails? Maybe.
• STAIR STRINGER to FRAMING CONNECTORS
• TOE NAILED FRAMING CONNECTIONS - traditional framing without steel connectors

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