Foundation-to-Frame Suite

Start below ground with fewer surprises.

Work out how much digging, concrete, stone and steel your foundation needs, and what it will cost. Any trade word you do not know is explained where it first appears.

Strip and pad foundations Kenyan D8-D20 steel KES 500 once
This works out quantities. It does not design your building. Digging, concrete and stone are measurement, and this tool is good at them. Steel that holds weight is design. Where the tool can safely suggest a footing it will, and where it cannot it will tell you to get an engineer instead of guessing. What you see on the surface of the ground is never a substitute for a soil test.
Stage 1 of 8Project

Stage 1 · Project

Do you have drawings from an engineer?

If you do, we will help you read the footing sizes off them. If you do not, the calculator will suggest a normal footing for a simple house — and tell you honestly when your situation is one only an engineer should answer.

How is your drawing measured? You can switch later without losing or changing the real dimensions.
Usually printed in the corner of the sheet. Leave blank if you have no drawings.
No engineer's drawing? You can still use this. The calculator will suggest a footing size that works for a simple single-storey house, and check it for you. For two floors it will give you the concrete but send the steel to an engineer. For three floors or more, or difficult ground, it will stop — those need a real design, not a rule of thumb.

Stage 2 · Site reality

What is under the ground?

If you have a soil test report, use its numbers. Just looking at the ground tells you when to worry, but it can never tell you how much weight the ground will carry.

Geotechnical information

Stage 3 · Ground levels

Capture the levels before digging.

A level survey controls depth, drainage, DPC, steps, and cut-and-fill. Four-corner values are a planning signal, not a substitute for a survey.

Stage 4 · Geometry

Enter dimensions from the drawings.

Use the measurement unit selected in Stage 1. Do not guess footing width, thickness, founding depth, or wall thickness.

How long is the foundation?

This is the total length of trench you will dig. Either give the outside size of the building and add up the inside walls, or if someone has already measured it for you, enter that one total.

Trench and footing

Blinding is the thin layer of weak concrete poured on the bottom of the trench before the footing. It stops soil mixing into your good concrete. 50mm is normal.

Foundation wall

Editable to match the actual stone size and bond.

Concrete specification from the drawing

Copy the specification. Do not select a stronger-looking mix as a substitute for the engineer’s design.
Use the mix stated in the structural notes or project specification.
Boundary: this page covers excavation, blinding, footings, foundation walls, backfill and disposal. Hardcore, anti-termite treatment, DPM/BRC and the ground slab belong in the Ground Slab calculation. The damp proof course (DPC) itself is laid after the ground floor slab, where the superstructure walling begins — it belongs to a future Walling calculation, not this one.

Stage 5 · Reinforcement

Steel in the footing

How to read the steel off your engineer's drawing

1. Find the right sheet. Look for one titled Foundation Details, Sections, or with a number starting S-. The architect's floor plans will not have the steel on them.

2. Find the footing drawn from the side. It looks like a wide flat rectangle with the wall sitting on top of it, and small circles or short lines inside — those circles are the steel bars seen end-on.

3. Read the note next to it. It will look something like 4Y12 or Y10-200:

  • 4 — how many bars, when a number comes first
  • Y12 — 12mm bars. Also written D12 or T12. Just take the number.
  • -200 — the bars are spaced 200mm apart
  • T&B — top and bottom, so two sets

4. Do not forget the starter bars. These stick up out of the footing to tie into the columns or walls above. On the drawing they are the bars bent in an L shape. Missing them is the most common mistake — add them as their own line below.

Enter one line per bar type. Cut length is how long each bar is after cutting — the drawing usually gives it; if not, measure the length it has to run. Stock length is the length you buy, normally 12m in Kenya.

What is it? (e.g. footing bottom, starters)Bar sizeHow manyLength of each (m)Length you buy (m)

Procurement allowance

Stage 6 · Local rates

Use prices from your supplier and site.

Enter prices from your local supplier, fundi, contractor, quarry or ready-mix company. The calculator does not assume that Nairobi prices apply to your site.

Use local rates only. Enter the actual unit price beside every applicable item. Do not include delivery inside a material rate unless the quotation includes it; record separate transport or mobilisation below.
Name where the prices came from so they can be checked later.
The final report records this date so an old estimate is not mistaken for a current quotation.

Steel price per 12 m stock bar

Earth handling

Stage 7 · Review and unlock

Check the inputs before pricing.

Nothing below reveals quantities or costs. Confirm the source and completeness of your inputs, then unlock the full foundation-to-frame suite.

Stage 8 · Full estimate

Your foundation breakdown.