Why count the foundation at all? (We explain on our fingers)
Imagine building a tall sandcastle on the beach. If you just pour a mountain of wet sand, it will quickly fall apart or settle. But if you dig a hole and make a strong base of stones, your castle will stand until the evening.
Foundation is the very “roots” of any building. It takes on the entire enormous weight of the walls, roof, furniture and people, and then evenly transfers this weight to the ground. If you make it too weak, cracks will appear in the walls and the house may warp. If you make it too powerful, you will simply bury hundreds of thousands of rubles in the ground. That is why it is so important to calculate everything correctly before construction begins.
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What types of foundations are there? (Three main types)
Before you count anything, you need to choose exactly where your house will stand. There are many options, but in private construction three simple types are most often used:
- 🎀 Strip foundation. Imagine a concrete strip that was buried in the ground exactly under all the walls of the house (both external and internal). This is the most popular option for brick and wooden houses.
- 🔲 Slab foundation. This is one continuous, smooth and thick slab of concrete, which is poured under the entire house. Excellent for marshy and soft soils.
- 📌 Pile foundation. Long metal or concrete pillars (piles) are simply screwed or driven into the ground. Ideal for light frame houses or uneven sloped areas.
What determines the size of the foundation?
You can't just pull numbers out of your head. In order for the house to stand strong, you need to know two main things:
- What kind of soil do you have on your site? If the ground is hard (rocky or dry clay), the foundation can be made not very deep. If the ground is soft (peat or sand with water), you will have to dig deep until you find solid support.
- How deep does the ground freeze in winter? When water in the soil freezes, it turns into ice and expands. This force is so enormous that it can easily push a light house out of the ground! Therefore, the bottom of the foundation (its base) should always be below the level where the ground freezes in winter.
How to calculate concrete for a strip foundation? (Simple math)
Let's consider the most common option - strip foundation. We need to know the volume in order to understand how many cubes of concrete to order from the plant. Volume in mathematics is calculated using the simplest formula that we learned at school: Length × Width × Height.
| Option | What is this? | Example in meters |
|---|---|---|
| 📏 Ribbon length | The sum of the lengths of all the walls of the house (both external and load-bearing inside). Perimeter | 30 meters |
| ↔️ Ribbon width | The thickness of your concrete wall. It should be slightly wider than the walls of the house themselves. | 0.4 meters (40 cm) |
| ↕️ Height (depth) | The part that is underground + the part that sticks out above the ground (base). | 1.5 meters |
We count:30 × 0.4 × 1.5 = 18 cubic meters (m³). This is exactly how much concrete concrete mixers will bring you!
🔥 Secret from experienced builders: Rule stock
Never order concrete directly “end-to-end” according to calculations! A trench in the ground is rarely perfectly level; some of the concrete will remain on the walls of the mixer, and some may spill. Always add7-10% marginto your calculation. Otherwise, just a couple of buckets may not be enough for you, and you will have to pay extra for the delivery of the whole car.
Check your calculations
Of course, to build a huge brick mansion with several floors you need to hire a professional engineer. He will calculate not only the concrete, but also the thickness of the iron reinforcement, the grade of cement and the load from snow on the roof. But to understand the budget for the construction of a small country house, bathhouse or garage, basic calculations are quite enough!
In order not to count everything on a piece of paper with a calculator, you can use our convenient concrete volume calculator for the foundation. Just enter your dimensions, and the program itself will show the required amount of materials.