How would you fix this hole in your workshop floor?

My workshop/garage is a pre-1940 block building detached from my house. 85% of the flooring is concrete, however, the remaining 15% is solid wood planks. The wood plank flooring is original to the building. The building is about 600sqft.
I have been repointing the walls for the past few weekends. I decided to finally tackle the entry way that needed to be addressed and was half assessed by the previous owners. There was a stone step sitting in front of the entryway on top of the flooring. As soon as I removed the stone step, I found the floor underneath had completely rotted. Underneath the flooring is dirt.

I’m a little stumped regarding the best way to go about fixing this hole. The rest of the wood flooring is about 100sqft +/-, and it’s in decent shape, but does need to be resealed soon. I’m not really in a position right now to pull all of the wood flooring. I don’t really want to lay new treated wood either because the issue will probably exist in the future since it’s directly on clay soil.

Here’s the hole today. I still need to remove some of the bad flooring, but I haven’t yet because it’s the only entry into the garage from the yard, and I don’t want someone tripping into a larger hole. Outlined in green is where the stone step was and where most the unstable wood is.

Any thoughts?

 

Do you know why that spot rotted so bad? If it stays dry, I'd be tempted to just sawzall out the bad spot and put in some new stuff for the time being.

 

2nd on Tear Out. Replace with concrete.

Only additional suggestion is to dig out 8" +/-, lay a compacted gravel base, then 6" concrete with rebar and a tie in to the existing slab.

You are only talking about 2 cubic yards of concrete. Small job, 1 concrete truck.

 

Dig it out and fill with crushed stone and top it off with pavers.

 

From the looks of the concrete next to the floor, tear out the wood floor.
Add a good layer of crushed rock.
Pour concrete.

 

It does not stay dry. I’m working on fixing that problem now before repairing this.

As much I knew this was the right answer, I was wishing there was an alternative. You’re right though, and I appreciate your reply! I don’t want to redo this work again once I have a final solution. I will patch with boarding for now, and plan to rip it all out either in the fall or next year. I currently have a back injury, so I’m unable to lift bags of concrete right now. My wife will not be happy if I continue to ask her to do the heavy lifting more than she already is.

 

Don't lift concrete bags. Them SOBs are heavy and hard to handle. I'll never understand why bag concrete mix is in paper bags.

Call the local concrete company. You can buy a truck load or a partial load.

If you do the bag route, plan on buying about 100+ bags, each bag only holds about 0.5 cubic feet. At 80+ lbs/bag........that is 8,000 lbs of bags to hump, likely more.

 

Looks ancient and dry rotted. I like the concrete idea.........I dunno - oh it was under a stone step. Pretty nuts.......cut back to good wood and pour concrete. Joists? Maybe lag to new step using PT lumber.....

 

For a temporary fix, you could cut out the wood, fill the hole with gravel, and put a large/heavy mat over the top of it.

 

Pretty easy to spend other peoples money.

I would first solve the water problem see what that takes go from there .

The fixing of the water problem may point in the direction of fixing the floor in a permanent way