Deck Railing Post Connections
How to connect railing-support posts on decks, balconies, stairways
POST a QUESTION or READ FAQs about how to install & connect vertical posts to support guardrailings or stair handrails on balconies, decks & stairways
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Guardrail for decks or stair railing post connections:
This article describes how to install & connect vertical posts to support guard railings or stair handrails on balconies, decks & stairways. Our page top photo shows two deck post connections: a supporting post capped with aluminum flashing and a deck guardrailing corner post lag-bolted to the deck's rim joist (photo-right).
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Post Connections for Deck or Porch Railings
Posts that run continuously from footings to railings (photo at left) are the strongest, but these are often not practical. (The stair and balcony shown had some other safety problems however.)
[Click to enlarge any image]
More commonly, the posts are attached to the rim joist or beam, preferably with through-bolts (see Figure 4-14 below)
While 4x4 railing posts are often notched where they connect to the beam, this creates a weak point in the post that will not meet the load requirements. Another problem is that the rim joist needs to be reinforced to keep it from rotating when a strong force is applied to the railing.
This can be achieved with lag bolts, steel strapping, or steel connectors tying the rim joist to the abutting joists. On sides where the rim joist runs parallel to the joists, solid
blocking should be lagged in place to keep the rim joist from rotating. Additional steel connectors may also be required.
Posts should be no more than 6 to 8 feet apart, depending on local codes.
Our sketch below illustrates through-bolting of deck railing or guardrail posts to the deck ledger. [Click to enlarge any image]
Structural Deck or Porch Posts Run Continuously from Pier to Guardrail or Post
Tall structural posts such as those shown in our deck photograph below are secured in turn to the pier top, the deck ledger, and if a roof is included, to the porch roof frame as well. While cross bracing may be needed at tall deck posts, this framing approach can give stronger, more rigid support to the deck or porch guardrail than that provided by posts nailed to or bolted to just the deck or porch rim joist.
Questionable Deck Guardrail "Posts" of under-sized materials?
The deck guard railing posts being constructed below by our friend Paul G. were made using 5/4 lumber.
Paul made very secure connections of these "posts" to the deck rim joist, but I didn't think highly of his design. Even secured well to the rim joist, these faux guardrail posts had a lot of flex that made me nervous.
Ultimately Paul says he was right however or that he thinks I'm an old maid worrier. He screwed his balusters to the deck rim joist and to the deck guardrailing top member all along the expanse of this deck.
The result was quite rigid and would (probably) pass code-specified guard railing load tests.
I also don't think that screwing a post into the grain-end of a supporting deck joist is a very strong connection.
Secure Deck or Porch Rail Balusters can Eliminate the Need for Guardrail Support Posts
Balusters can be nailed or screwed directly to the rim joist and to the guard railing at the top of the deck guardrail, or balusters screwed along a stair stringer and secured at top to a stair guardrailing can be strong enough that additional 4x or larger posts may not be required.
Watch out: if your deck screws split the baluster it is no longer securely connected to the deck rim joist or guardrail top. There are two hazards that ensue: a loose, insecure guard railing (depending on the number of split baluster ends) and a child hazard (open baluster spacing lets a kid fall off of the deck or porch).
Just below we show a baluster that was split during installation. Multiple screws split the baluster end making this connection insecure and unsafe.
Below is a well secured baluster. The galvanized deck construction screws that work so well for deck floor installation can split balusters and may require pre-drilling to avoid that trouble.
Some builders shoot nails to hold the balusters during initial construction (the small rust spots in the photos below) following up with proper structural connectors later - a practice that's ok with me (DF) as long as the number of penetrations doesn't increase the risk of split balusters.
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