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Foundations for a modular home — blocks, slab, screw piles

3 foundation types for a modular home. Comparison of cost, build time, load capacity and durability. When is a full slab worth paying for?

Date: 2026-03-08
Reading time: 9 min
Author: MP Modular

3 foundation types — which one to choose?

A modular home weighs 6–15 tonnes (depending on model and fit-out). That is significantly less than a typical brick-built house (60–100 tonnes), so you do not always need a full slab foundation. Below are the three most common solutions, each with realistic costs and use cases.

1. Concrete blocks (cheapest)

Cost: €550–900 for a 38 m² home
Time: 1 day of work
When to use: load-bearing ground (sand, compacted clay), flat terrain, seasonal or 3-season home, container

Blocks 20 × 20 × 40 cm or larger placed at 6–8 points under the module frame. Levelled, on a layer of lean concrete or compacted sand. This is the oldest and simplest method — used for decades under site cabins and containers.

Downside: not accepted everywhere in a building design. Check with the local planning office.

2. Screw piles (mid-range option)

Cost: €900–1,550 for a 38 m² home
Time: 0.5 day
When to use: unstable ground, sloping terrain, flood zones (home "on stilts"), recreation

Steel piles mechanically screwed into the ground — no excavation, no concrete. Load capacity of a single pile: 3–7 tonnes. 8–12 piles are needed for a 38 m² home. The advantage is that they can be unscrewed and the home moved to a different location.

Another advantage is zero ground disturbance — you do not need to strip topsoil, there are no earthworks, and you can set up on a lawn.

3. Slab foundation (most durable)

Cost: €2,200–4,000 for a 38 m² home
Time: 5–10 days (excavation, reinforcement, pour, curing)
When to use: permanent year-round home, registered address, larger home (74 m²), underfloor heating installation

A classic reinforced concrete slab 20–25 cm, on a base of crushed stone and lean concrete. Underfloor heating can be run in the screed. The best insulation from the ground (10 cm XPS foam under the slab).

A slab is required when the home is classified as "permanently attached to the ground" — that is, in most cases of a permanent residential home.

Choosing the foundation — 4 questions

Question 1: How long will the home stand?

1–2 years (site office, rental container): blocks. 5–10 years (recreation, second home): screw piles. 20+ years (permanent home): slab.

Question 2: What is the ground like?

Order a geotechnical survey (€110–330) — you will learn about load-bearing capacity, groundwater level, and frost depth. Without it, everything is guesswork.

Question 3: What is my foundation budget?

€650 — blocks. €1,300 — screw piles. €3,300 — insulated slab. Do not try to save on foundations — corrections cost 5× more than getting it right the first time.

Question 4: Should the home be permanently attached to the ground?

If yes (permanent residential home) — slab or piles with bracing. If not (temporary, portable structure) — blocks are enough.

Who does the foundation?

The modular home manufacturer usually does not do foundations — that is the client's task or a local construction crew's. Good practice:

Pitfalls worth knowing about

Summary

A good foundation is 30% of a modular home's success. Cutting corners here hurts the most — because once the home is set down, it cannot be lifted again. Invest in a geotechnical survey and a consultation with a local structural engineer before making the decision.

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