Land and Site Assessment — What Decides a Site Is Buildable in Ireland
On this page
Five things decide this: planning status, access, soil, water, wastewater. Any one can kill a sale-agreed purchase.
When this matters most
You're still choosing sites, you've gone sale-agreed, or you've just inherited land and don't know if it's buildable.
When this doesn't apply
You already own a buildable site with full planning permission, tests done, and an engineer appointed.
Decision matrix
If: Site is outside the rural settlement boundary and never had planning
Then: Check the county development plan local-needs policy first. Rural housing policy tightened in most counties since 2022.
If: Site has planning permission but it's over 5 years old
Then: It may have lapsed. Check expiry date; renewal is rarely automatic.
If: Site has no public sewer within reasonable distance
Then: You need a Domestic Wastewater Treatment System (DWWTS) with percolation area. Get a percolation test before exchange of contracts.
If: Ground is rock, gravel, or sand (Class 1–2)
Then: Standard strip foundation likely. Cheapest foundation.
If: Ground is clay, silt, made ground (Class 3–4)
Then: Raft foundation likely. Add €15,000–€25,000 to budget.
If: Ground is peat, soft clay, or fill (Class 5+)
Then: Piled raft or driven piles. Add €40,000–€80,000.
Frequently asked questions
How much does a site assessment cost in Ireland?
€1,500–€4,000 for a soil test, percolation test, and water yield test together. Engineers typically charge €300–€600 for a desktop feasibility study on top.
What is a percolation test?
Measures how fast water drains into your soil. EPA Code of Practice sets minimum standards (e.g. T≤90 minutes for soil, ≤30 for subsoil); results dictate which wastewater system your site can take.
Can I build on a site with no planning permission?
Not in nearly any case for a one-off house. Some very limited agricultural and maintenance works are exempt under Schedule 2 of the Planning Regulations. Building a new dwelling is not exempt.
What is ribbon development?
A planning policy: building houses strung along a single rural road. Most county development plans refuse ribbon development outright. If your site is in a ribbon position, planning is very likely to be refused.
How deep does a borehole need to be for a private well?
Site-specific. Typical Irish domestic wells: 30–80 m deep. Yield (litres per minute) is what matters, not depth. Get an EIS test before purchase.
Is radon a problem on rural Irish sites?
Yes, particularly in the southeast (Co. Carlow, Wexford, parts of Wicklow). 1 in 10 Irish homes has elevated radon. Your engineer will specify a radon barrier and possibly a sump.
Sources
EPA, Code of Practice: Domestic Wastewater Treatment Systems (2018, updated 2021). https://www.epa.ie/publications/compliance--enforcement/waste-water/
Geological Survey Ireland, Irish Soil Classification System. https://www.gsi.ie/
Department of Housing, Rural Housing: Sustainable Rural Communities Guidelines for Planning Authorities 2020. https://www.gov.ie/
Quick decision matrix
| If your situation is | Then choose |
|---|---|
| Site is outside the rural settlement boundary and never had planning | Check the county development plan local-needs policy first. Rural housing policy tightened in most counties since 2022. |
| Site has planning permission but it's over 5 years old | It may have lapsed. Check expiry date; renewal is rarely automatic. |
| Site has no public sewer within reasonable distance | You need a Domestic Wastewater Treatment System (DWWTS) with percolation area. Get a percolation test before exchange of contracts. |
| Ground is rock, gravel, or sand (Class 1–2) | Standard strip foundation likely. Cheapest foundation. |
| Ground is clay, silt, made ground (Class 3–4) | Raft foundation likely. Add €15,000–€25,000 to budget. |
| Ground is peat, soft clay, or fill (Class 5+) | Piled raft or driven piles. Add €40,000–€80,000. |
Frequently asked questions
How much does a site assessment cost in Ireland?
€1,500–€4,000 for a soil test, percolation test, and water yield test together. Engineers typically charge €300–€600 for a desktop feasibility study on top.
What is a percolation test?
Measures how fast water drains into your soil. EPA Code of Practice sets minimum standards (e.g. T≤90 minutes for soil, ≤30 for subsoil); results dictate which wastewater system your site can take.
Can I build on a site with no planning permission?
Not in nearly any case for a one-off house. Some very limited agricultural and maintenance works are exempt under Schedule 2 of the Planning Regulations. Building a new dwelling is not exempt.
What is ribbon development?
A planning policy: building houses strung along a single rural road. Most county development plans refuse ribbon development outright. If your site is in a ribbon position, planning is very likely to be refused.
How deep does a borehole need to be for a private well?
Site-specific. Typical Irish domestic wells: 30–80 m deep. Yield (litres per minute) is what matters, not depth. Get an EIS test before purchase.
Is radon a problem on rural Irish sites?
Yes, particularly in the southeast (Co. Carlow, Wexford, parts of Wicklow). 1 in 10 Irish homes has elevated radon. Your engineer will specify a radon barrier and possibly a sump.
When this matters most
You're still choosing sites, you've gone sale-agreed, or you've just inherited land and don't know if it's buildable.
When this doesn't apply
You already own a buildable site with full planning permission, tests done, and an engineer appointed.
Briefs in this stage
17 in-depth answers for this stage of the build. Pick the one that matches your question.
Flood Risk Maps in Ireland — How to Check opw.ie Before You Buy a Site
opw.ie hosts floodinfo.ie, the national flood hazard mapping. Check it before you sign contracts on any site near a river or coast.
flood risk map IrelandRead brief →
Foul Drainage Connection in Ireland — Mains Sewer, Treatment System, or Septic
Pre-Connection Enquiry Form to Uisce Éireann is the first step. €100–€300, with a decision in 4–6 weeks.
foul drainage connection IrelandRead brief →
Irish Soil Classification — Class 1 to Class 5+ and What Each One Costs You in Foundation
Class 1–2 (rock, gravel): strip foundation, cheapest. Class 3–4 (clay, silt): raft, mid. Class 5+ (peat): piled raft, most expensive.
Irish soil classificationRead brief →
Is My Site Buildable in Ireland? The Five Checks That Decide It
Planning status, access, soil, water, wastewater. Any one of these can kill a sale-agreed purchase.
is my site buildable IrelandRead brief →
Land Registry Check in Ireland — Folio, Map, and What to Look For Before You Buy
A Land Registry folio costs €30 and shows ownership, burdens, rights of way, and map. Always check before exchange.
land registry check IrelandRead brief →
On-Site Electricity for a Self-Build in Ireland — Temporary Connection, Generator, or Solar
Temporary ESB connection: €1,500–€3,000. Generator: €100–€200/week. Solar + battery: €3,000–€5,000 but no fuel cost.
on-site electricity self buildRead brief →
Percolation Tests in Ireland — EPA T-values, What They Mean, and What Costs When You Fail
T-value (time for water to drop 1mm) must be ≤90 minutes in soil, ≤30 in subsoil. Most rural sites need both tests.
percolation test IrelandRead brief →
Ribbon Development in Ireland — The Planning Policy That Refuses Houses Along Rural Roads
Most county development plans refuse ribbon development outright. If your site is in a ribbon position, planning is very likely to be refused.
ribbon development IrelandRead brief →
Rural Housing Policy in Ireland 2026 — Local-Needs Tests and How Counties Vary
Outside settlement boundaries, you must prove a rural housing need. Criteria vary sharply by county; some have tightened since 2022.
rural housing policy Ireland 2026Read brief →
Septic Tank vs Mains Sewer in Ireland — When Each Applies and What It Costs
Mains sewer: connection charge €5k–€15k to Uisce Éireann. Septic: €8k–€15k installed plus €300–€500/year maintenance.
septic tank vs mains sewer IrelandRead brief →
Site Access in Ireland — Road Entrances, Sightlines, and the Road Opening Licence
A new entrance onto a public road needs planning permission and a road opening licence. Adds 8–26 weeks if sightlines are tight.
site access IrelandRead brief →
Site Assessment Cost in Ireland — Soil Test, Percolation Test, Water Test, and What to Order Together
Bundle soil + perc + water tests for €1,500–€3,000. Add a desktop feasibility study from an engineer for €300–€600.
site assessment cost IrelandRead brief →
Site Office and Welfare for a Self-Build — What You Need by Law (SHWW 2013)
Toilet, washing, drinking water, and a place to dry clothes. Mandatory under the Safety, Health and Welfare at Work (Construction) Regulations 2013.
site welfare self buildRead brief →
Site Purchase Costs in Ireland — Stamp Duty, Legal Fees, and What Adds Up
Stamp duty: 1% up to €1m, 2% above. Legal fees: €1,500–€3,500. Site survey: €300–€600. Searches: €300–€800.
site purchase costs IrelandRead brief →
Site Security on a Self-Build in Ireland — Hedges, Hoardings, CCTV, and Insurance
Hire a 2.4 m hoarding and a CCTV pole for €200–€400/month. Site insurance won't pay out if the site is unsecured.
site security self build IrelandRead brief →
Site Survey in Ireland — Topographical, Measured, and Boundary Surveys
Topographical survey: €400–€800. Measured survey: €300–€600. Boundary survey: €500–€1,500. Order before you instruct the architect.
site survey IrelandRead brief →
Well Yield Tests in Ireland — How to Confirm a Rural Water Supply Before You Buy
Yield (litres per minute) is what matters, not depth. A 30–80 m borehole needs a 24-hour pump test to confirm flow.
well yield test IrelandRead brief →
Where to go next
Next decision
The next step in your build sequence.
- Foul Drainage Connection in Ireland — Mains Sewer, Treatment System, or Septic →
- Is My Site Buildable in Ireland? The Five Checks That Decide It →
- Land Registry Check in Ireland — Folio, Map, and What to Look For Before You Buy →
- On-Site Electricity for a Self-Build in Ireland — Temporary Connection, Generator, or Solar →
- Ribbon Development in Ireland — The Planning Policy That Refuses Houses Along Rural Roads →
- Site Access in Ireland — Road Entrances, Sightlines, and the Road Opening Licence →
- Site Office and Welfare for a Self-Build — What You Need by Law (SHWW 2013) →
- Site Security on a Self-Build in Ireland — Hedges, Hoardings, CCTV, and Insurance →
- Site Survey in Ireland — Topographical, Measured, and Boundary Surveys →
Branch into
Adjacent decisions at the same stage.
- Flood Risk Maps in Ireland — How to Check opw.ie Before You Buy a Site →
- Percolation Tests in Ireland — EPA T-values, What They Mean, and What Costs When You Fail →
- Rural Housing Policy in Ireland 2026 — Local-Needs Tests and How Counties Vary →
- Septic Tank vs Mains Sewer in Ireland — When Each Applies and What It Costs →
- Well Yield Tests in Ireland — How to Confirm a Rural Water Supply Before You Buy →
Watch out for
Common mistakes, hidden costs, gotchas.
- Percolation Tests in Ireland — EPA T-values, What They Mean, and What Costs When You Fail →
- Septic Tank vs Mains Sewer in Ireland — When Each Applies and What It Costs →
- Site Assessment Cost in Ireland — Soil Test, Percolation Test, Water Test, and What to Order Together →
- Site Purchase Costs in Ireland — Stamp Duty, Legal Fees, and What Adds Up →
- Irish Soil Classification — Class 1 to Class 5+ and What Each One Costs You in Foundation →
Compare with
Alternative approaches worth knowing.