Universal Foundation Concrete Calculator

Unsure which foundation you need? This universal wizard suggests the best type based on soil and load, then calculates concrete volume.

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Category Foundation Concrete

Step 1: Site Analysis

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About

Choosing the right foundation is the single most critical decision in construction. A foundation must distribute the weight of the building (dead load) and occupants (live load) into the ground without sinking or shifting. The choice depends heavily on two factors: the bearing capacity of your soil and the weight of your structure.

This Universal Calculator acts as a decision-support tool. If you are unsure whether to pour a monolithic slab, a strip footing, or piles, our 'Wizard Mode' analyzes your inputs to suggest the safest and most economical option. Once selected, it provides a quick estimation of the concrete volume required. This tool bridges the gap between geotechnical theory and practical material ordering.

foundation selector soil bearing capacity slab vs strip construction wizard

Formulas

This tool aggregates formulas for the three main foundation types.

1. Monolithic Slab:

V = L × W × T

2. Strip Foundation:

V = Perimeter × Width × Depth

3. Pile Foundation:

V = N × (π r2h)

Reference Data

Soil TypeBearing Capacity (kg/cm²)SuitabilityRec. Foundation
Rock / Bedrock> 5.0ExcellentStrip / Pad
Gravel / Coarse Sand3.0 - 4.5GoodStrip / Slab
Fine Sand (Compact)2.0 - 3.0ModerateSlab (Reinf)
Clay (Dry/Hard)2.5 - 4.0VariableDeep Strip / Pile
Clay (Soft/Wet)< 1.0PoorPile / Raft
Peat / Organic< 0.5Very PoorSpecialized Pile
Silt0.5 - 1.5Poor (Heave risk)Raft / Pile
Fill / Made GroundUnpredictableDangerousEng. Design Req.

Frequently Asked Questions

A Slab-on-Grade (Raft) is ideal for flat ground with moderate soil where you want a finished floor immediately. It works well to 'float' over slightly uneven soil support. A Strip foundation is better for sloping sites, areas with deep frost lines (where you need to dig down), or when building a crawlspace or basement.
You can perform a simple field test. Dig a small hole 50cm deep. If you hit solid rock, it's bedrock. If the soil crumbles easily and feels gritty, it's sand/gravel. If it can be molded into a ball that holds its shape, it contains clay. If it's dark, spongy, and smells organic, it's peat (do not build on peat without professional help).
No. This tool provides volume estimates and general suggestions based on common practices. It cannot account for specific site anomalies, water tables, or seismic risks. Always consult a licensed engineer for the final structural design.