Indonesian Foundations: No Frost Rule, Design-Driven Depth

The requirement

There is no fixed footing depth in Indonesia, and no frost line. The rule is Permen PU No. 29/PRT/M/2006, Bab III.3.1.d.i. It sets depth by your ground instead. The footing base must sit on soil that can carry the load. Your site’s soil check sets the depth you dig to.

Why no frost rule? Indonesia is tropical all year, so the ground never freezes. Cold countries make you dig below a frost line. There is no such line here at all.

The rule comes from the Ministry of Public Works (Pedoman Persyaratan Teknis Bangunan Gedung). Bab III.3.1.d.i spells out the depth test. The footing base must reach a soil layer with enough stable bearing capacity. A ground and site investigation has to confirm that layer. The building must also not settle past its limits over its life. So dig to whatever depth your soil report calls for. Any website that prints one fixed depth is guessing.

Permen PU 29/2006 · Bab III.3.1.d

1 footing
2 ground

Width is worked out, not fixed. Footing width works the same way. It comes from bearing and settlement sums, “per standard soil-mechanics theory”. The method lives in SNI 8460, the national ground design standard. Get your width from a geotechnical engineer working to that standard. It depends on your soil and your load.

Concrete grade and rebar cover: see SNI 2847. The rule does not name a concrete grade. It points to SNI 2847, the national concrete design standard, current edition. Rebar cover sits in the same standard. We are not printing an MPa or mm figure here. Sources we checked did not agree on what SNI 2847 says. Until we confirm it against the standard’s own text, we will not guess. Ask your structural engineer, or check SNI 2847 yourself.

Thickness is not fixed either. Minimum footing thickness is a design output. The engineer checks punching shear, one-way shear and bending for your exact footing. The rule does not give a set figure.

Work it out on site

Your soil report sets the depth. Your engineer sets the width. Once you have both, the concrete volume is plain maths, and the app does the sum. Say you have a strip footing to pour. These are example numbers, not code minimums:

Total length of trench: 24 m
Footing width: 0.5 m. Example only. Yours comes from a geotechnical engineer working to SNI 8460 for your soil and load.
Footing depth: 0.6 m. Example only. Your site check sets it.

Volume = length × width × depth:

24 × 0.5 × 0.6 = 7.2 m³

So you would order about 7.2 cubic metres. Then add a bit for spillage and an uneven trench. Most builders tack on 5 to 10 per cent. Swap in your own numbers and the app does the rest.

Do it in 5 seconds

Part of the Indonesian building-rules hub. One national rule book, plus the tools that work to it.
Setting out the stairs on the same build? See Indonesian stair rules.

Sources

Permen PU No. 29/PRT/M/2006 (Pedoman Persyaratan Teknis Bangunan Gedung), Bab III.3.1.d (foundation depth set by ground/site investigation, concrete and rebar deferred to SNI 2847, width deferred to soil-mechanics calculation). Read it at peraturan.bpk.go.id.
SNI 2847:2019 (Persyaratan Beton Struktural untuk Bangunan Gedung, BSN) — the referenced concrete-design standard for grade and cover figures, not independently confirmed for this page. Catalogue at bsn.go.id.
SNI 8460:2017 (Persyaratan Perancangan Geoteknik, BSN) — the referenced geotechnical standard for footing-width calculation, not opened during research for this page. Catalogue at bsn.go.id.

Read this first. Permen PU 29/2006 dates from 2006, issued under Indonesia’s pre-2017 Building Law framework. The current Building Law (UU 6/2017) and its 2021 implementing regulation may since have produced a newer regulation restating this Bab — this couldn’t be confirmed either way during research, so treat it as a live risk. Concrete grade and rebar cover figures are deliberately not printed on this page because they could not be independently confirmed against SNI 2847’s own text — get those from your structural engineer. Always confirm the current instrument on pu.go.id — and get your ground checked by a site investigation — before you dig.

Frequently asked questions

Is there a minimum foundation depth in Indonesia?

No. There is no fixed depth and no frost line, because Indonesia is tropical. Permen PU No. 29/PRT/M/2006, Bab III.3.1.d sets depth by your ground instead. The footing base must reach a soil layer with enough stable bearing capacity. Dig to whatever your site's soil investigation calls for.

How wide does a footing need to be?

There is no fixed width in this rule. Width comes from bearing and settlement sums, per standard soil-mechanics theory. The method sits in SNI 8460, the national geotechnical design standard. Get your width from a geotechnical engineer working to that standard, not from a number on a website.

What concrete grade goes in a footing?

The rule points to SNI 2847, the national concrete design standard, current edition. It does not name a grade itself. Sources we checked did not agree on what SNI 2847 sets, so we are not printing an MPa figure until we confirm it against the standard. Ask your structural engineer, or check SNI 2847.

What about rebar cover?

Same story. Cover is set inside SNI 2847, not in the building rule itself. So we are not printing a cover figure here either. The reason matches the concrete grade: it needs checking against SNI 2847's own text first. Ask your structural engineer for your job's cover.

Is footing thickness fixed?

No. Minimum thickness is not a set figure in the rule. It is a design output. The engineer checks punching shear, one-way shear and bending for your exact footing. You cannot read the number off the regulation.