Concrete Foundations in George — Strip, Raft & Engineered Footings

Engineered foundations across George and the Garden Route — correct ground assessment, correct reinforcement, correct concrete. The thing your whole house stands on has to be right.

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What We Do

The three foundation types we build most often on the Southern Cape.

Strip Foundations

The standard for most residential builds on firm ground — excavated trenches to engineered depth, reinforcement to spec, concrete to SANS 10100. Width and depth sized by the engineer based on soil and load.

Raft Slabs

Engineered raft foundations on weaker soils — a thickened reinforced slab spreading the load across the entire footprint. Used in clay, poorly compacted fill, and some coastal sites where differential settlement is a risk.

Piled & Engineered Footings

For poor-bearing ground, slopes, or high loads, we coordinate with geotechnical engineers for piled foundations or engineered footings. Outside of standard residential — but we handle the coordination and execution.

How It Works

Ground assessment. The geotechnical report and the engineer’s foundation design drive everything. We review both before quoting — there’s no standard foundation, just the right one for your specific site.
Set-out and excavation. Accurate set-out from the drawings, excavation to the specified depth, and inspection of the bearing soil. If the soil doesn’t match the assumed condition, we stop and get the engineer back on site.
Reinforcement and formwork. Rebar cut, bent and placed to engineer’s drawings, with correct cover blocks. Formwork where needed. Every placement is inspected before the concrete is called up.
Pour and vibrate. Ready-mix concrete to the spec mix design, slump tested, placed in lifts, and vibrated properly. No cold joints, no honeycombing, no short-changing the spec.
Cure and inspection. Concrete cured correctly, stripped after the minimum time, and released for superstructure only after engineer sign-off. All certification kept on file for NHBRC and handover.

Foundation Types, and What Chooses Between Them

A foundation transfers the load of the building into ground that can carry it. Which type you need is decided by two things: what the building weighs and how it is arranged, and what the ground will actually take.

Strip footings run continuously under load-bearing walls and are the standard residential answer on competent ground. Simple, economical, and entirely dependent on founding at the right depth on the right material.

Pad footings carry point loads — columns, posts, a steel frame — and are sized individually for the load above them.

Raft foundations spread the whole building’s load across one reinforced slab. They come into their own on weak, variable or made-up ground, where a strip footing would settle differentially and crack the building above it.

Piled foundations carry load past unsuitable ground to competent material below. Expensive, and occasionally the only honest answer on a difficult site.

Nobody chooses between these from a plan. The choice comes from what the trial holes show.

Type	Carries	Suits	Watch
Strip footing	Continuous wall loads	Competent, uniform ground	Founding depth and material
Pad footing	Point loads from columns	Framed structures, verandas	Individual sizing per load
Raft	Whole building, spread	Weak or variable ground	Engineered; more steel and concrete
Piles	Load taken to depth	Poor ground over competent material	Cost and access for the rig

Garden Route Ground, Specifically

Soils here vary enormously over short distances, and a foundation designed for the wrong profile is the most expensive mistake available on a build.

Sandy coastal profiles around the Mossel Bay to Plettenberg Bay strip drain well but can be loose near the surface and need founding below the mobile layer.

Clays inland of George behave completely differently. Clay shrinks as it dries and swells as it wets, and a foundation founded within the zone of seasonal moisture change gets lifted and dropped every year. Cracking in a building on clay is very often a foundation depth problem rather than a structural one.

Low-lying erven around Wilderness, Sedgefield and the Great Brak flats can carry a high winter water table, which changes both the design basis and the practicality of excavating in the wet months.

This is why we dig trial holes before pricing anything structural. The difference between founding at 600 mm and founding at 1.2 m is the difference between two quite different jobs, and finding that out at excavation stage is far better than finding it out later.

Excavation, Inspection and the Pour

The sequence on a foundation is short and every step in it is a checkpoint that cannot be revisited.

Setting out from the surveyor’s pegs. Excavation to the design depth, with the trench bottoms cleaned rather than left with loose spoil in them. Inspection of the founding material to confirm it is what the design assumed — this is the moment a geotechnical surprise appears, and it is the cheapest moment for it to appear.

Then reinforcement placed to the drawing with correct cover and laps, a municipal or engineer’s inspection where required, and the pour. Cover is not a detail here: on the coast it is the whole defence against chloride reaching the steel.

Foundation walls up to floor level, with the damp-proof course bedded correctly and continuous — a DPC that stops short, or is bridged by plaster or a paving level outside, is a rising damp problem built into the house on day one.

Backfill in compacted layers, and drainage arranged so that surface water runs away from the building rather than into the backfill zone beside it.

What Foundations Cost You, and Why the Ground Decides

Foundations are the line item that varies most between two apparently similar houses, and it is almost never the design that drives it.

The price is built from excavation volume and how hard the digging is, whether rock is encountered, how much of the excavated material can be reused and how much has to be carted away, imported fill and compaction, the concrete and the reinforcement, and access for plant.

Two erven a street apart can differ substantially on all of those. That is why we will not price a foundation off a plan alone, and why any quote that arrives before someone has looked at the ground carries either a large contingency or a large variation waiting to happen.

The other honest point: an engineer’s fee on a residential foundation is a small fraction of the concrete cost, and a fraction of a fraction of the cost of underpinning a house that has settled. Where the ground is doubtful, the design is the cheapest part of the job.

Common Questions

What concrete strength do you use?

Residential foundations are typically 20–25 MPa, commercial and high-load 30 MPa+, all to the engineer’s spec. Mix designs are from reputable ready-mix suppliers with traceable delivery notes.

What if the soil is poor?

If the geotechnical report shows poor bearing, we follow the engineer’s alternative design — deeper strips, a raft slab, ground improvement, or piled foundations. We don’t shortcut foundation design on any soil condition.

How long do foundations take to build?

A standard residential strip foundation runs 2–3 weeks from excavation to ready-for-superstructure, weather and inspection permitting. Rafts and engineered footings run longer. Programme is committed to in writing.

How deep should foundations be?

Deep enough to found on undisturbed competent material, below topsoil and below the depth at which the ground moves seasonally — which is why there is no single figure. On clay soils inland of George that depth is governed by the zone of seasonal moisture change and is often deeper than people expect. Trial holes before design are how the number gets established rather than guessed.

Do I need an engineer for foundations?

For anything beyond a straightforward deemed-to-satisfy solution on known good ground, yes — and in practice that means most sites where the soil is variable, where the building is more than single storey, where loads are unusual, or where the foundation forms part of a retaining structure. The fee is small against the concrete, and very small against remediating a building that has settled.

What is the best foundation for clay soil?

It depends on how active the clay is and how deep the seasonal moisture zone runs. The options are founding below that zone on strip footings, spreading the load across a stiffened raft so the whole building moves together rather than differentially, or piling through to competent material. What does not work is a conventional shallow strip footing sitting inside the active zone — that is the classic cause of seasonal cracking in houses on clay.

How long do foundations take?

Excavation and pouring is usually a matter of days on a normal residential footprint, but the programme is set by inspections and by the ground rather than by the digging. Trench bottoms have to be inspected before covering, reinforcement before pouring, and concrete needs curing time before the walls go up. Wet weather and a high water table both extend it, which is one reason foundation timing matters on the Garden Route calendar.

What happens if you hit rock or water?

Both are common enough here to plan for. Rock changes the excavation method and the cost, and sometimes changes the foundation design for the better since rock is excellent bearing material. Water means dewatering during excavation and can change the design basis entirely. Either way it is a variation, which is exactly why we dig trial holes before pricing — so it is a known quantity rather than a surprise mid-job.

Can you build on an old foundation?

Sometimes, but not on assumption. An existing foundation was designed for the building that was on it, and it needs to be exposed, inspected and assessed against what you intend to put on it now. Where the new building is heavier, taller or differently arranged, or where the existing footing has deteriorated, reuse is often false economy. An engineer’s assessment settles it.