Joist Hangers & Post & Beam Framing Connectors
Guide to Choosing & Using Porch & Deck Structural Connector Brackets & Plates
     

• FRAMING CONNECTORS & JOIST HANGERS - Wood Framing & Deck & Porch Construction, Structural Joist Hangers, Brackets, & Connectors for posts, beams, joists, railings, ledgers, etc.
  • Deck & Porch Post & Beam Connectors: steel post cap connectors, plywood post to beam cleats, scabs, other connectors
  • How to toe-nail wood framing connections; what makes toe-nailing work?
  • Details of installing Simpson Strong Tie framing connectors for I-Joists
  • Installation Details for Steel Framing Connectors for I-Joists
  • Details for using through-bolting or lag bolts for wood framing, deck & porch construction
• CONNECTORS, FASTENERS, TIES - separate article
• DECK & PORCH CONSTRUCTION - home
• DECK CONSTRUCTION BEST PRACTICES - separate article
• DECK DESIGN & BUILD - article series home
• FRAMING FASTENERS, NAILS, SCREWS - separate article
• Questions & Answers about what types of joist & beam hangers & connectors are required for wood framing & deck constructoin: joist hangers, connectors, steel tie plates, etc.
• References

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This article includes excerpts or adaptations from Best Practices Guide to Residential Construction, by Steven Bliss, courtesy of Wiley & Sons. Also see our 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.

Details about choosing the right structural connectors for decks and how they should be installed are at FRAMING CONNECTORS & JOIST HANGERS.

At FRAMING FASTENERS, NAILS, SCREWS, & HIDDEN we discuss choosing the proper nail, screw, or hidden fastener for fastening deck boards, railings, or joist hangers. Spans, sizes and spacings for deck joists and deck beams are discussed in detail at FRAMING TABLES, SPANS for DECKS and are shown in Table 4-7 and Table 4-8. Basic building framing information is found at FRAMING SIZE & Spacing, Age, Types. Also see Deck Framing Tables, Spans and Deck & Porch Connections: Ledger Boards. And see Preservative-Treated Framing Lumber. See Rot-Resistant Deck Lumber & Flooring for a discussion of lumber and flooring alternatives to preservative-treated wood. At LECTRICAL OUTLET, HOW TO ADD & WIRE we describe using nail stops to protect wiring & plumbing when routing those through wood framing members.

This article series discuss best porch & deck construction practices, including choice of framing materials, decking or flooring choices & installation, how to select and use deck and porch structural and flooring fasteners, actual deck & porch framing construction details & connections, deck joist & beam span tables, how to build leak-proof rooftop decks, construction of covered & screened porches, deck & porch railing construction & materials, choices of finishes and stains for decks & porches, and past & current deck lumber preservative treatments with related health & environmental concerns.

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.

How to Make Secure Post to Beam or Girder Connections for Decks & Porches

As described in Best Practices Guide to Residential Construction, Chapter Four, Best Construction Guide for Building Decks and Porches:

For the strongest connection of beam to post, place the support beam directly on top of the posts (photo at left), rather than bolting them to the side, so the full load is transferred to the posts.

To keep the post in place and to prevent any twisting or shifting, the connection should be reinforced with steel strapping, a steel connector, or a treated plywood cleat.In general, notching a 4x4 post will leave too little wood for an adequate connection [but notching a 6x6 post can work, as illustrated below]..

For a more streamlined appearance, joist hangers are acceptable. Make sure the hangers and nails are approved by the manufacturer for use with the new types of pressure- treated wood (ACQ or ACZA) and fill all the holes in the hangers with properly sized nails. In general, nail into the joists with 1 1/2-inch joist-hanger nails and nail into the beam with 10d to 16d common nails, as specified by the hanger manufacturer.

A double 2x beam can rest on a notched 6x6 post, as shown. For the strongest connection of joists to the support beam, the joists should sit on top of the beam

In our photo the 6x6 post was notched to leave a thick component that could be through-bolted (or lag bolted) to the girder. You'll also see toe-nails up through the post top into the girder bottom, and additional common framing nails securing the post to the beam.

Don't cut the notch out of the center of the 6x6 post for a double 3x beam - the remaining lumber on the post top will be too thin and risks splitting and failure.

An alternative to using steel framing connectors to tie a post to a beam is shown at left. A scab(green arrow) using 2x lumber is secured to the girder and to the post below.

But in our photo the installer put the scab on just one side of the post, and used just 10d common nails for fasteners.

To be secure, the scab should be bolted to the girder and through the post as well. Through-bolts (illustrated below) 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.

A look at the other side of the deck girder (beam) above shows that the builder must have been short on nails. We don't see nails securing the two 2x10's together - at least none on this side (a weaker construction method), and we see no fasteners making any attempt to tie the girder to the post top. Everything relies on that 2x6 scab that was ticky-tacked to one face of the post and beam. We recommended the addition of through bolts.

When drilling holes through a scab or other framing member, and if multiple bolts are to be installed (red circles on the scab in the photo at above left), I [DJF] like to stagger the bolt hole positions in order to assure that no two bolts run through the same vertical grain in the wood.

That's the strongest connection as it reduces the chances of splitting of the wood between two holes drilled in the same grain section of the lumber.

You'll also notice that we don't place the bolts too close to the end of the scab nor too close to the top or bottom edge of the girder nor too close to the top of the post - locations where splitting may be more likely.

The two 2x10's comprising the deck girder in our photo above have not been bolted together.

That may be OK if the girder was toe-nailed from opposing sides. Some builders who want a stiffer girder add structural adhesive and even a treated plywood plate between the 2x lumber to build the girder. Especially where a plywood stiffener is installed, be sure to provide flashing over the top of the girder to protect the structure from water and frost damage.

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.

At a minimum, use hot-dipped galvanized hardware. With pressure treated 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. And at FRAMING FASTENERS, NAILS, SCREWS, & HIDDEN we include examples of fasteners that should not be used in joist hangers, such as drywall screws and other non-structural screws. or roofing nails.

Also see FRAMING FASTENERS, NAILS, SCREWS, & HIDDEN and see New Preservatives and Corrosion where we describe structural fasteners designed for use in pressure-treated lumber.

Our photo (above left) shows a typical steel joist hanger used to speed and aid the construction of a deck. Notice that the height of the steel hanger is matched to the depth of the joist. Continuing from from Best Practices Guide to Residential Construction:

Like other deck components, metal fasteners are subject to numerous stresses. The sealers and stains typically used on decks provide little protection to fasteners, and the copper-based chemicals used in most waterborne preservatives accelerate corrosion in many metals.

When the fasteners corrode, they contribute to decay in the surrounding wood, further weakening the connection.

Also notice that the proper galvanized steel joist hanger nails were used, not roofing nails or other fasteners. If you select the proper depth of joist hanger to match the depth of the deck joists, the manufacturer is giving you a clue about the number of nails required to make a safe and secure connection - every hole in the hanger gets a nail.

Watch out: choose the right joist hanger for the size of joist being supported. Don't use a joist hanger intended for 3x4's to hang a 2x6 or larger framing member - the number of nails won't be sufficient.

If you encounter a structure already built with this mistake, fixing the connections is usually easy: add the required number of additional fasteners by toe-nailing the joist or rafter from opposing sides, using an appropriately sized framing nail or galvanized framing nail if outdoors. (Typically 12d common galvanized).

How Many Nails or Screws do I Need to Connect Two Framing Members?

The architect or engineer who designs a building specifies the number and type of framing connectors to be used for each type of connection. But there are also good sources of connector information from the manufacturers of framing connectors (right in the catalog or in installation sheets), as well as in various engineering and carpentry texts.

A still more basic clue is the number of holes in the framing connector itself.

Watch out: the number of holes in a typical joist hanger is a clue to the number of nails that the manufacturer expected you to use to make a secure connection. Our pocket-knife is pointing to missing framing nails in the 2x4-sized framing-connector above. There were no nails into the butting framing member.

It is not necessary to use steel joist hangers if the joist is properly toe-nailed from either side into the ledger board, provided that the proper size and number of nails are used.

Our illustration (left, adapted from a Double-Shear stamping on a steel joist hanger) explains why toe-nailed lumber connections can be very strong. We drew in spray-brown color, a representation of wood framing members showing the abutting of 2x lumber (vertical in the illustration) with a header or beam (horizontal in the illustration).

The crossed nails, when applied close together (as guided by the framing connector or by the hand of a competent framing carpenter), form a very strong wood-to-wood connection. Use of toe-nailing, or angled opposed framing nails (Double-Shear in Simpson Strong-Tie's patented[10] joist hanger such as the item adapted above), can permit the use of fewer total nails in a wood frame construction.

The strength of a toe-nailed wood framing connection will be affected by:

• How close to opposite one another the two nails are placed
• Using nails of sufficient length to adequately penetrate both wood members
• Nailing the toe-nails at the proper angle (45 degrees).
• Placing nails high enough from the edges of the abutting member (vertical in our sketch) as to have adequate purchase and to avoid simply splitting out a little chip of the edge of the 2x.
• Placing nails low enough in that same member to be sure that the length of the nail penetrates both the abutting member and the nailed-to facing member.
• Using the correct number of nails specified for the lumber sizes involved.

Too few nails: Using too few toe-nails in a framing lumber connection is going to make a weak structure that could collapse.

Using too many nails in a framing lumber connection when toe-nailing or in any position for that matter will also cause a weak framing connection that can lead to structural collapse. That's because an excessive number of nails actually fractures the lumber.

Our photo (left) shows about 30 nails shot by the builder during framing of this home. The framer was trying to drive a recalcitrant stud into position. Clamps might have worked better. This stud was so split as to lose its structural integrity, and replacement of this wall stud was needed.

Because the "toe-nails" cross one another in the header or ledger board when used to secure a deck joist, this connection can actually be stronger than end-nailing the deck joists from the other side of the ledger or girder.

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