Need advice on footings for new outdoor stairs

[atgcpaul]

The plans for the stair addition to my porch were approved. I want the
four posts to sit on metal anchors buried in the concrete. I don't want the
posts buried in the concrete footers.

It's not a big deal for the longer posts closer to the house. I know I can
prevent them from swaying. My concern is with the bottom 2 posts. There
will be three stair stringers--two that flank the outside of each post and one
down the middle. The middle stringer will be anchored to a concrete footer.

If the bottom riser is bolted to the two corner posts and also attached to the
middle stringer, will I have to worry about the posts/rails swaying? By code it
needs to withstand a 200lb side load but I want that thing to be as rock solid
as possible for my own ego.




Thanks,
Paul

[capncarl]

Paul
A simular project I completed required the post to be removable to allow for large appliances to be carried into the house. Not wanting the movement that metal anchors or plates allow when attached to wood we purchased a PVC square fence post that is designed to fit over a 4x4 treated post. It was set in the correct location and the footer was poured around it. I sawed it off at a suitable height and packed a fist full of gravel in the pvc post for drainage. The post was a tight fit but if it had any movement there were plans for wedges to be driven in the loose side.

capncarl

[crokett]

Paul, will the bottom posts also be anchored to a footing? Why would you not attach them to a footing? The bottom riser will help some with stiffness but to reallykeep the top of the posts from moving you would need to brace the top. The only thing you can do is securely attach the hand rail. On my deck I ran the hand rail over the top of the posts rather than as in your design. This helped a lot to keep them stiff but I know it does not look as pretty.

[LarryG]

Caveat: not a structural engineer, although I've done the architectural detailing on a blue million of these things.

With or without the bottom of the post anchored to concrete, this won't be a good detail. Attaching the newel post to the stringer will help (especially if there's a short, partial stringer on the other side of the post, sandwich-style), as will carefully fitting the tread around it. But it won't be as strong as you'd like even at the outset, and it will only loosen up with time. The riser is only about 6" - 7" tall and the post cantilevers roughly 36" above the tread. That's about a 6:1 ratio. As a general rule of thumb, 2:1 is about what it should be.

Something similar to what capncarl describes is your best option. The structural post should be embedded in concrete 18" - 24" and then trimmed out to give the finished look you want. (I personally would use a square steel tube, not having had good luck with PT lumber staying sufficiently straight.)

[atgcpaul]

I guess I wasn't clear. The bottom posts will be anchored to the concrete
footer with one of these:






The posts will then be bolted to the front riser and the blocking that is
attached to the middle stringer.




If I use one of these footing connectors in conjunction with the posts bolted
to the riser in front, will I be OK?

Thanks, Paul

[vanguard]

I'm pretty sure that's the recommended approach. I just saw Tom Silva do that very same thing with a garage post that supported the roof on a front wall. Should work just fine for you.

[atgcpaul]

I'm pretty sure that's the recommended approach. I just saw Tom Silva do that very same thing with a garage post that supported the roof on a front wall. Should work just fine for you.

I think the difference between that garage episode and my post is that the
garage post does not need to withstand any side loads like the stair post
does.

Paul

[JR]

I once did a one-post free-standing installation using the CBSQZ solution. It had a hose reel on it, generating a fair bit of side stress. Solid as a rock.

I'd think your solution would be tough as nails.

JR