Mounting 6x6 post to concrete

[aalleexx]

Needing advise please. I'm going to be putting up some 6x6 wood posts to support moderately heavily loaded free-standing loft in my shop. I want to spread the load as much as possible to the concrete by using a 12x12x1/4" steel plate to sit each post on. I have the plates already and am wondering about best way to attach posts to them. Would the post base included in the picts be feasible to attach to the plates? What would be the best way? Any advise appreciated, thanks in advance.

 

[AC-WC]

Lag bolts for the base to wood post, I would predrill the holes to the shank size of the lag. I would lag each hole the base has.
For base to floor I presume you have concrete? These in the correct diameter.

https://www.menards.com/main/hardware/fasteners-connectors/anchors/wedge-anchors/red-head-reg-trubolt-reg-1-2-hex-nut-expansion-wedge-anchors/40281/p-1444436192360-c-8727.htm

 

[aalleexx]

Lag bolts for the base to wood post, I would predrill the holes to the shank size of the lag. I would lag each hole the base has.
For base to floor I presume you have concrete? These in the correct diameter.

https://www.menards.com/main/hardware/fasteners-connectors/anchors/wedge-anchors/red-head-reg-trubolt-reg-1-2-hex-nut-expansion-wedge-anchors/40281/p-1444436192360-c-8727.htm

would you recommend welding the post bases to the plate? Button weld the pre-drilled bolt holes?

 

[AC-WC]

The post bases are already welded to the plate. They did a nice job of welding if you can't tell the weld is there.

 

[racecougar]

You could weld the post bases to the plates, or just make your own post bases with those plates (assuming you can weld).

 

[racecougar]

The post bases are already welded to the plate. They did a nice job of welding if you can't tell the weld is there.

The OP wants to use 12x12 plates to spread out the load.

 

[AC-WC]

The OP wants to use 12x12 plates to spread out the load.

Ahhhh-now I see! I thought it was a breakdown of the post base dimensions.

IF you're a good welder I would weld it and not worry about the button hole weld on the holes of the base plate. I presume the post base is thinner metal vs the 1/4" plate? If you're not a good welder of different thickness material I would predrill the 1/4" plate to match the holes in the post base.

 

[aalleexx]

Guess I better drill the plate then.

 

[67King]

I'd probably drill the plate, and anchor to the concrete through that plate. I think the load will spread just by sittong on the plate. Don't think attaching the two will give you any advantage.

 

[CV428]

If you have a minimum of 4" concrete, 3000psi, you likely don't need to spread that load further unless that loft is going to be extremely heavy or have a gantry crane under it, or you plan on really spanning the posts out. What's the estimated total weight, number of posts, and span?

If it was me and I was dead set on a spread footer, I would draft up a 1pc weldment and have a local fab shop weld them up (burn table, weld plates, don't bother with square tube because it'll never fit a post nicely enough due to corners). I couldn't find any "off the shelf" spread footings for 6x6 that fit the bill. Most post mounting brackets are for X/Y location and don't provide any real level of load distribution beyond the footprint of the post itself, and the rigidity is from the structure above it.