Strip Foundation in Ireland — When It Works, What It Costs, and What the Engineer Will Check
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Strip on good soil: €120–€180/m² of footprint. Cheapest foundation. Class 1–2 ground only.
A strip foundation in Ireland is a continuous strip of concrete under every load-bearing wall. It is the cheapest option: €120–€180/m² of footprint, or €18,000–€27,000 for a 150 m² house. It works on Class 1–2 ground (rock, gravel, dense sand) and is the standard foundation for sites with confirmed good ground conditions. A soil test (€1,500–€3,000) confirms the soil class; the engineer specifies the strip width and depth based on the test. Building Regulations 2023 TGD-A (Structure) sets the structural rules. Add €8–€15/m² for a radon barrier (1,200-gauge polythene) and a radon sump in high-radon areas (Carlow, Wexford, parts of Wicklow). Strip foundation requires a competent builder; standard practice for most Irish self-builders.
TL;DR
Strip foundation in Ireland: €120–€180/m² of footprint, the cheapest option. For Class 1–2 ground (rock, gravel, dense sand).
A 150 m² house on a strip foundation: €18,000–€27,000 for the foundation alone. Add €8–€15/m² for a radon barrier (Carlow, Wexford, parts of Wicklow).
Requires a soil test (€1,500–€3,000) to confirm the soil class. Engineer specifies the strip width and depth.
When this matters most
Your site has Class 1–2 ground and your engineer has confirmed a strip foundation is viable.
When this doesn't apply
Your site has Class 3+ ground or significant slope. Consider raft or piled raft instead.
Frequently asked questions
How much does a strip foundation cost in Ireland?
€120–€180/m² of footprint. For a 150 m² house: €18,000–€27,000 for the foundation alone. Add €8–€15/m² for a radon barrier in high-radon areas.
When is a strip foundation the right choice?
Class 1–2 ground (rock, gravel, dense sand). Confirmed by a soil test. Engineer specifies the strip width and depth. Standard for most Irish self-builds on good ground.
Do I need a radon barrier with a strip foundation?
Yes, on every new build in Ireland since 1998. Most are a 1,200-gauge polythene membrane. In high-radon areas (Carlow, Wexford), add a radon sump and extract fan.
Sources
Building Regulations 2023, Technical Guidance Document A (Structure). https://www.gov.ie/
Geological Survey Ireland, Irish Soil Classification System. https://www.gsi.ie/
Frequently asked questions
How much does a strip foundation cost in Ireland?
€120–€180/m² of footprint. For a 150 m² house: €18,000–€27,000 for the foundation alone. Add €8–€15/m² for a radon barrier in high-radon areas.
When is a strip foundation the right choice?
Class 1–2 ground (rock, gravel, dense sand). Confirmed by a soil test. Engineer specifies the strip width and depth. Standard for most Irish self-builds on good ground.
Do I need a radon barrier with a strip foundation?
Yes, on every new build in Ireland since 1998. Most are a 1,200-gauge polythene membrane. In high-radon areas (Carlow, Wexford), add a radon sump and extract fan.
When this matters most
Your site has Class 1–2 ground and your engineer has confirmed a strip foundation is viable.
When this doesn't apply
Your site has Class 3+ ground or significant slope. Consider raft or piled raft instead.
Where to go next
Branch into
Adjacent decisions at the same stage.