Suspended vs Solid Floor in Ireland — Timber Suspended, Solid Slab, or Beam-and-Block
On this page
Solid slab (raft) is the standard for most Irish self-builds. Suspended timber or beam-and-block for difficult sites.
Three floor types for an Irish self-build. Solid slab (raft): a reinforced concrete slab on the ground, with insulation and a radon barrier beneath. Standard for most sites because it's cheap, integrates underfloor heating, and provides a continuous insulation layer. Suspended timber: a timber floor over a subfloor void, supported on the perimeter foundation. Used on sites with high water tables or difficult ground. Beam-and-block: precast concrete beams with infill blocks, grouted together. Used on sites with high water tables or where a solid slab isn't suitable. Most Irish self-builds use a solid slab (raft). Building Regulations 2023 TGD-A (Structure) governs.
When this matters most
You're at foundation design stage and need to choose the floor build-up.
When this doesn't apply
The floor is poured.
Sources
Building Regulations 2023, TGD-A (Structure). https://www.gov.ie/
Frequently asked questions
What is the cheapest floor for a self-build in Ireland?
Solid slab (raft): €180–€260/m², including subfloor insulation and radon barrier. Cheapest and most common for Irish self-builds.
When is a suspended floor used?
High water table, contaminated ground, or sites where a solid slab is unsuitable. Suspended timber is faster on these sites; beam-and-block is the concrete alternative.
Can I put underfloor heating on a suspended floor?
Yes, but it's more expensive than on a solid slab. Suspended timber requires a low-profile heating system; beam-and-block needs a screed on top to embed the pipes.
When this matters most
You're at foundation design stage and need to choose the floor build-up.
When this doesn't apply
The floor is poured.
Where to go next
Next decision
The next step in your build sequence.
- Foundation Depth in Ireland — 900 mm, 1.2 m, or Below Frost Line →
- Foundation for a Timber Frame House in Ireland — Raft Is the Standard →
- Piled Raft Foundation in Ireland — For Peat, Made Ground, and Soft Clay Sites →
- Raft Foundation in Ireland — The All-Rounder for Class 3–4 Ground and Subfloor Insulation →
- Subfloor Insulation in Ireland — PIR, EPS, or Mineral Wool, and What Part L 2022 Demands →
Branch into
Adjacent decisions at the same stage.
Watch out for
Common mistakes, hidden costs, gotchas.
- Foundation Cost by Soil Class in Ireland — The €/m² by Class 1 to Class 5+ →
- Foundation Gotchas in Ireland — The Six Things That Catch Self-Builders Off Guard →
- Radon Barrier in Ireland — Where It's Needed, What It Costs, and the Carlow-Wexford High-Risk Map →
- Strip Foundation in Ireland — When It Works, What It Costs, and What the Engineer Will Check →