Slab foundation for 16 x 20 greenhouse prices?

sailorfred

What can I expect to pay for a detached concrete slab for a lightweight 16 x 20 greenhouse in Sunnyvale, CA?

The greenhouse is a kit that's aluminum framed with twinwall polycarbonate glazing. The loads should be fairly light, although I want it to be able to support 55 gallon drums filled with water (~450 lbs).

The greenhouse will have 110 and 220 electrical outlets and a water supply, as well as a drain. Web surfing indicates I can drain into the ground, rather than needing to connect to the sewer.

The kit manufacturer doesn't warn against aluminum in contact with concrete, but I've seen some web pages saying there will be corrosion. Is this correct?

They do warn against "new" pressure treated (copper impregnated) timbers causing corrosion against aluminum.

Do you have suggestions for how to attach the greenhouse frame to the slab that will last?

sailorfred

Would I be more likely to get an answer in the construction forum?

joasis

If it were me, and we have built greenhouses for a commercial grower here, I would pour a footing/stem wall for the perimeter, and fill with pea rock or gravel over sand for a base....you can attach the aluminum rails to the concrete without any real concerns, but you may wish to use stripping of plastic or even doubled #30 felt to keep the aluminum and concrete kinda isolated.