Best way to keep beams vertical on concrete posts

by Dabusan
(Toronto, Canada)

I'm building a two foot high free standing deck (10 X 15).

I've got holes dug for 4 posts per beam for the 15ft width.

I'm planning on using 2 X (2 X 10 ) screwed together for my beams. My question is how do I keep my beams vertical when they're sitting on the concrete posts?

All the steel ties that I've seen (i.e. Simpson) provide the ability to place a beam on a low post bracket but not to vertically stabilize them. They're also usually designed for 4 X 4 posts and are an inch too wide when you marry two 2X 10 together.

This would normally be fine if the upper deck framing was anchored to the house with a ledger board but this is a free standing deck.

Does the box framing of the upper deck when attached to the beam provided the beam rigidity so that it doesn't collapse sideways like a parallelogram?

I keep thinking I'll be able find a steel tie shaped like a tall letter "U" that I could drop the beam into and that would be secured in the concrete of the posts but all I can find is much shallower post base style brackets.

How do people keep beams vertical on free floating decks?

Thanks for your help.

Editor's Comments

One of the best ways to secure beams to support posts is to use a 6x6 instead of a 4x4 support post. Notch the top of the 6x6 to create a ledge or rabbet that the entire double 2x10 beam can sit on. Bolt the beam and post together with 1/2" carriage bolts. It will be rock solid.

This is so much better than using one of the thin H style brackets. Also with the H style brackets you have to make the beam thicker by adding 1/2" plywood between the 2x10s to make it a true 4" wide.

You will not have any risk of the beam being wobbly.

And yes, once the framing is secured to the top of the beam it does provide some rigidity to prevent the beam collapsing sideways. There may be some other hardware options available but not commonly found. However this explains a far better solution.

Watch this video on securing beams to posts:

Also even more important for a free standing deck is to brace the posts to the beams or joists as needed. Also applying a 2x4 or 1x4 diagonal brace from one corner of the deck to the other corner nailed to the underside of the deck joists will also stiffen up the structure and help prevent racking.

But mostly the bracing does that. Watch this video on using bracing:

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Jul 02, 2014
Low level deck continues to challenge
by: Dabusan

Thanks very much for your thoughts and videos. I can appreciate how on a 40" deck like the one in the video the combination of 6 X 6 posts and cross supports would make the deck very rigid however on a 24" deck I don't really have the height for a post. Instead I'm stuck mounting the beams directly on the concrete posts in some sort of metal bracket.

i.e. 1" deckboards, 2 X 8 frame and joists, 2X10 doubled beam and concrete posts that are a few inches above ground level doesn't leave much room for a notched 6 X 6 or cross supports.

I'm thinking I need to find some tall U shaped brackets or turn my beams into a box frame of their own. Does this make sense?

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