plywood base for paver patio?

11 years ago

I had my greenhouse (sort of a 70's trombe wall thing) removed. It was built on the south side of my house and the floor was at the level of the house crawl space, poured cement bottom with cement block wall up to ground level where the glass portion then started.
Now, after tearing it down, the builder put joist hangers on the walls and then plywood to bring it up to level with the surrounding ground. The plan was to cover that with a waterproof barrier and then gravel, sand and pavers. The plywood portion is 7' x 36'.
After the winter, the plywood, walls, and joists are now covered with some kind of mold or moss INSIDE this pit. There is no ventilation and no way to install any. I am very uneasy about this. I am afraid that after some years the plywood will rot, my expensive terrace will sink, etc.

My builder assures me this will not happen. He thinks treating the space with moldex will solve the problem, but I think removing the plywood and filling the space with gravel would be the only sure thing. That is what I wanted from the start, but he said no, this would be better.
Expert opinions would be appreciated.

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Comments (10)

millworkman
11 years ago
Pictures would certainly help, but this sounds completely incorrect and unacceptable from my thinking.
marcinde
11 years ago
so what you're saying is the exterior grade comes across, there's a significant step down to the floor of what was the greenhouse, and then a significant step back up to floor height? Did the builder offer any explanation for why there should be any framing there at all? It sounds like the void could've been filled in with gravel and the pavers laid on top of that. Is there airspace or access the builder was trying to preserve?
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AMR444
Original Author
11 years ago
outside view
AMR444
Original Author
11 years ago
underneath plywood patio. towards the end there is a hatch for access to fireplace cleanout. grave and pavers would be put on top and brought up to level of hatch cover.
AMR444
Original Author
11 years ago
inside space under what will be paver patio
marcinde
11 years ago
that looks so bizarre. Ordinarily I try not to second guess the contractor because there are usually site issues I can't see from a photo, but I'm baffled by the decisions here.
millworkman
11 years ago
I agree, I know we spoke about it yesterday and I am also stumped as to the thought process behind what he did.
AMR444
Original Author
11 years ago
I think the thought process was based on 3 things.
1. there is need to access the fireplace ash clean out from inside this space. 2. gravel to fill the pit would be about 28 yards and the source and dump trucks are about 45 min to one hour away from the site here. 3. the contractor wanted to keep his carpenters employed building something.
None of these are good structural reasons, I know. But the question now remains: Will it work to support the planned patio of layers of gravel, sand, and pavers for the next 50 years??
The site is on top of a hill, nothing higher for a mile.
millworkman
11 years ago
No, I do not believe it will as there is nothing to stop the wood from rotting, period.
nigelsgarden
11 years ago
The best you could do with what you have is a wood porch, but ventilation is still a problem.

Probably best to start over and find a gravel supplier that can deliver the gravel with a tandem or a large straight dump truck.

Not sure about any drainage issues..........