Q&A / 

How To Connect Deck Railing Post to Deck

Deck Railing Connection TIPS


Deck Post Danger

Deck railing posts are the foundation of a deck railing system. They must be strong.

It's easy to connect deck railing posts to the floor joists of the deck.

No Lag Bolts!

Don't lag bolt a deck railing post to the outer band board that's nailed to the ends of the floor joists. The nails that pass through the band board into the ends of the floor joists have minimal holding power.

The reason why nails driven into the end of a stud or joist don't hold well is because the nail is parallel to the micro grow tubes that make up the tree. If you could look at the end of a deck joist with a high-powered microscope it would resemble what the end of a bundle of unwrapped drinking straws would look like.

CLICK HERE to get FREE & FAST BIDS from local deck builders in your city or town.

Use this Simpson Strong-Tie Connector

I completely rebuilt a deck on my own home recently. I didn't build the deck originally. 

To connect the new posts to the floor joists I used two Simpson Strong-Tie DTT2Z ZMAX galvanized 14-gauge 2x deck tension tie connectors at each post base where it passed next to the floor joists.

deck railing post connector

Here's the connector I used on my own deck posts. You need two per deck railing post. WATCH the VIDEO above to see how it goes in. CLICK THE IMAGE HERE NOW TO BUY THESE CONNECTORS.


CLICK HERE to get FREE & FAST BIDS from local deck builders in your city or town.


24 Responses to How To Connect Deck Railing Post to Deck

  1. Thanks for the video on decks, is there any chance you could show a deck that was properly attached?


    • Larry,
      You can't put rafters for a patio covers on the tails of the rafters or trusses. They must be supported by the wall of the house. There's a few ways to do this. Detail 'A' in this flyer: http://www.prbd.com/pubs/guides/carports.pdf is the neatest way to do this. You could put the ledger lower and leave the existing roof assembly in place if you have the height to do that. There's a couple of other ways but they really require some intense framing.

  3. Wish you could see how I attached the rail posts. Simply put, they are bolted into the deck frame, including the support timbers. Had to use threaded rod, large washers and nuts. There is NO movement. The advantage of designing the deck myself.

  4. @Larry: Connecting roof supports directly to a deck sounds like trouble waiting to happen if you ask me. Decks moving/swaying is one thing, but attaching a roof to same moving/swaying object just doesn't strike me as anything but problems. I just ripped apart a 600sq/ft deck (will be putting in a slightly raised stone patio in place) which has a partial roof overhang. The (single) supporting 4x4 that holds the corner of the roof up was/is isolated from the deck. Went straight through the deck from ground to roof.

    @Tim: RE:the one that sent you over the edge... I think he misunderstood your statement about lag bolts being unacceptable. You probably meant their use in your particular example was unacceptable (i.e. notched 4x4 directly to 2x10 and nothing else). I'm guessing they're supposed to be going from one 4x4 into another supporting/vertical 4x4. But yeah, the 4x4 converted to a 2x4 thing is a joke. Not sure how code even allows something that dumb in general.

  5. Tim,

    Thanks for always providing such terrific info to all of us. This is very important and useful to know.

    I appreciate you taking the time to keep us informed.

  6. Tim, keep up the good work is assisting us. Keep in mind there will always be someone with little expertise or knowledge about what they are griping about.

  7. Tim, thanks for the video!

    I just ran out to inspect the posts on my 30-year-old deck.
    Mine are also notched, but with the post facing the opposite way from what's in Tim's video. That is, the tongue is on the inside of the sill, so that pushing the post outward tries to pull the tongue up, rather than snap the post off. And the posts are mounted with bolts, not lag screws.

    I remember that my town's building inspector told me that the railings have to withstand 200 pounds. 200 pounds is hardly any force at all. I asked him whether he meant 200 pounds, or 200 pounds per foot, or what. He couldn't understand the difference between 200 pounds and 200 pounds per foot. I can think of something to say about that, but I'll keep quiet.

  8. Tim,
    Seems to me the railing spindles/rail assemblies are mounted backwards. Tops and bottoms of the spindles are nailed in, so as the fasters age, an overactive teen bumping against them could knock some loose and he would take a tumble. Simply reversing the installation so the 'pretty' side is outside would be safer. Isn't this code in some jurisdictions?

    Joe Bobst

  9. I've built a fair number of decks and never knew this - at least the decks I've built have been fairly low to the ground. My daughter and son in law have just got a new house and will need a deck which will be really high (walk out basement) just looking at the pictures of the information lets me know what to do - and it would be more secure than not using that hardware - that I've never seen. I've always keep the 4 x 4 intact and tried to bolt it both ways - or even build a box around it sometimes (which I'm sure is very good there is no wiggle at all no matter how many years go by). Thanks for the info.

  10. Tim, I went right out an checked my deck. This deck was a replacement for a deck built of 2x4s that were rotting out. There were no spindles between the posts, so it was very unsafe for kids.

    My new deck was built to code, but it does have the notch-out of the 4x4s you mentioned. The descending piece is longer, though, and seems pretty sturdy. There are metal braces on all the joints, so I think it's in pretty good shape. Still, I will know what to look for in the future!

    Thanks for the info.

  11. regarding your being upset with your reader's mail:
    you did this right. You delivered what you promised: you gave a tip. If a reader needs more information, he should get extra help, which may or may not come free.

  12. Hi Tim I watched the video that you refereed to in deck raining post and I see nothing wrong with the video What I saw was a very poor deck rail post and an accident waiting to happen , The like to Simpson strong ties , well that is just common sense these days with winds and snow loads , I have a copy of that brochure on my desktop its that much I use it or refer to it . Tim Great Video

  13. Thanks Tim. I have seen this issue addressed by a few different people. The solution I personally like the best is to cut out a 4x4 hole in the decking and drop the entire 4x4 post on the inside of the deck frame. You can lag bolt from the outside of the frame into the 4x4 or even drill a hole for nut and bolt. To make it even better, you can beef up the framing around the 4x4 to suck it tight. Even with a Strong-tie, I would think this method is even stronger and safer since you're not cutting out half of the 4x4. What do you think?

  14. Hi Tim, Please don't be to upset with the resent post. Many people have been scam by other people looking just to make a buck. They can't believe there are some people like yourself that are truly an angel in disquise just trying to help others. My deck post railings were just like the one shown in the video which I am replacing with 4x4 bolted to joists. Now I'll add the Simpson Strong-Tie for a safer railing. Many many thanks and may God bless you. Bruce

  15. TIM, you were TOO KIND in calling the deck maker a CARPENTER, I'd be kind in calling this person a street sweeper.

    These are the kind of jobs that result in people getting injured in deck collapses that have happend in the Chicago area in recent years !!!

  16. I bet this has been asked before. Was a permit pulled? were the plans approved? Was it built to plan? was it inspected? these are some of the safety nets to help protect the DIY from himself. As to the ho-rah about the bracket manufacturer. A simple statement made now and then to the effect that IF you local material supplier does not carry this brand go to the web site of the supplier of the parts that they do carry and look for this type of guide. If you can't find it, the information in this guide will help you understand what you need to do to safely install the parts that you are using. If in doubt, ask the building inspector BEFORE you begin.

  17. I am the owner of a handyman service and i have seen a lot of loose rail posts I have repair a lot of them with bolts but after seeing your video i will start using the simpson strong- tie it looks like a great repair you sent the info on the strong tie from simpsom I read the article you didn't have to make a video it took 5 seconds to bring up the paper work If the guys not very happy about it because it takes a few seconds to look up paper work thats their problem I am glad you send us tips and better ways to do a job and will always read your emails
    thank you for what you do

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