Building a concrete slab might cost more upfront, but it is also a nicer and more secure option for a greenhouse foundation.
While you might have an existing deck or concrete slab to sit the greenhouse on, below we will describe the steps to create a concrete base from scratch.
1. Build The Perimeter
Mark 4 corners at the size of your greenhouse with stakes. Go around the 4 points using string levels and secure them at the desired height. As mentioned earlier, it is recommended to calculate a 6-inch height.
2. Level The Ground
Make sure the soil is leveled before building the wooden perimeter. Dig a little trench to hold boards on each side at the level of the strings you previously measured.
This formwork is used to hold the concrete that will be poured later. You can use recycled boards.
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3. Pour The Concrete
Once the formwork is leveled and secured, place a layer of gravel, sand, and water to get a more stable base on which you’ll pour the concrete. Before making the concrete mix, place a grid of rebar with 15x15" squares.
The mesh should be a few centimeters above the ground. You can place plastic tiles at various points under the grid. Pour the concrete, spread it, and screed at the level of the woods to smooth the surface. To avoid cracks it is necessary to keep watering the base as it dries.
This may require some technique, so if you’re not sure how to do this, hire a professional to do it for you.
4. Assemble The Greenhouse
Allow drying for two days before removing the wooden perimeter and assembling the greenhouse. The concrete takes 21 days to dry completely. Use anchors to drill into the concrete and secure your greenhouse.
Ask for our expert's help in case of any doubts and don’t forget to take a look at the installation videos we have recorded for assembling Planta Greenhouses’ various models.