Underpinning and subsidence · Ireland
Underpinning in Ireland
Cracks, sloping floors or doors that won't close can mean the ground under a house has moved. Underpinning puts new support under the foundations, and it starts with a structural engineer, never a guess. Tell us what's happening and one experienced groundworks and underpinning contractor who covers your county rings you.
FreeFive quick questionsOne contractor in your county rings you
- Engineer's assessment first
- Every fact sourced and dated
- Nothing booked until you say yes
Get an underpinning quote
Five quick questions, then one contractor who covers your county rings you.
Step 1 of 6
What's happening with the house?
What type of property is it?
Has a structural engineer looked at it?
When are you hoping to start?
With an engineer's report
Have the report ready
Underpinning is priced from the engineer's design: the method, how deep it goes and how much of the house it covers. The contractor who rings will ask for it.
The Irish Times quotes an engineer: underpinning first needs a ground investigation to see how far down to go. 29 October 2026.
An engineer is booked
Keep that appointment
The engineer decides whether underpinning is needed at all, and what kind. The contractor can talk to you now and price the work once the design is done.
Irish Times, Irish Examiner: the engineer surveys and designs before any work.
No engineer yet
Start with a structural engineer
Cracks alone don't show that a house needs underpinning. BRE's crack scale treats cracks up to 5 mm as mostly cosmetic, and an engineer quoted in The Irish Times says the worry is evidence of recent movement. A chartered structural engineer looks at the crack pattern, the ground and the drains first.
You can still send your details. The contractor can talk it through with you, but the engineer decides.
BRE Digest 251 categories; The Irish Times, 24 April 2020.
Your insurer is involved
Talk to the insurer first
Policies ask you to tell the insurer as soon as reasonably possible and give full details within 30 days. Some insurers arrange the repair through their own network of contractors. You can still ask for an independent price; tell the insurer you're doing it.
Aviva Homeshield policy booklet (2024); Bank of Ireland home insurance summary (2025).
Building beside the house
The engineer sets the foundations
Digging next to a house for an extension or a new building can take away ground that supports the existing foundations. That is one of the standard reasons for underpinning. The engineer designing the new work decides whether the existing wall needs it.
Wikipedia, Underpinning.
Rather talk now? Call 087 162 1846 (8am–8pm)
What underpinning is
New support under the foundations, once an engineer says so
Underpinning strengthens the foundation of an existing building by taking it deeper or wider, so it rests on firmer ground or spreads its load further (Wikipedia). In Irish houses it mostly follows subsidence: the ground under part of the house stops supporting it evenly, that part drops a little, and walls crack (Irish Examiner).
Most cracks are not subsidence. BRE Digest 251, the scale engineers use, treats cracks up to 5 mm as aesthetic (BRE). And when it is subsidence, Irish engineers say old leaking drains are usually behind it, so the drains get fixed first.
This site never tells anyone their house is safe or that it needs underpinning. A chartered structural engineer who has seen the house decides. Read house subsidence and when underpinning isn't needed.
Methods
Underpinning methods
The engineer picks the method from the ground, how deep firm ground is and the access. Tap for how each one works.
Cracks
How engineers grade cracks
BRE Digest 251 sorts cracks into six categories by width and damage. It's the scale Irish engineers and surveyors use. Width isn't everything: a crack that's still growing matters more.
- 0Hairline, under about 0.1 mmNegligible. No action needed.
- 1Fine, up to about 1 mmTreated with normal decoration. Usually internal finishes only.
- 2Up to about 5 mmEasily filled. Some external repointing may be needed. Doors and windows may stick slightly.
- 35 to 15 mm, or several of about 3 mmSome opening up and patching by a mason. Doors and windows stick, service pipes may fracture.
- 415 to 25 mm, depending on numberSections of wall broken out and replaced. Frames distorted, floors sloping noticeably, walls leaning or bulging.
- 5Over 25 mm, depending on numberMajor repair, partial or complete rebuilding. Walls lean badly and need shoring. Danger of instability.
0 to 2: aesthetic3 and 4: serviceability5: stability
Source: BRE, Assessing cracks in houses, setting out the categories in BRE Digest 251. BRE stresses this is a simplification: whether cracks are widening over time also matters.
How it works
From the first crack to sign-off
The order Irish engineers describe. Nothing is booked until you say yes.
- 01
Record the cracks
Dated photos, inside and out. Don't fill them yet.
- 02
Engineer's assessment
A chartered structural engineer grades the cracks and finds the cause.
- 03
Fix the cause
Usually old clay drains, replaced with sealed uPVC.
- 04
Design and works
The engineer designs it, a contractor prices and builds it.
- 05
Settle, then repair
Cracks filled six months to a year later. Keep the sign-off.
We don't inspect houses or do building work. We pass your request to one experienced groundworks and underpinning contractor who covers your county. The full process, step by step.
Costs
What's actually published in Ireland
No Irish contractor or public body that we could find publishes an underpinning price list. These are the dated Irish figures that exist. The cost guide.
- €16,000Mini-piling under one Dublin semi-detached house, 6 m deep, at trade rates, 2020The Irish Times
- ~€3,000A ground investigation with trial holes, an engineer's estimate, 2020The Irish Times
- 5% / 10%What an insurer can hold back until the repair is done: under or over €40,000Aviva policy booklet
Guides
Underpinning and subsidence guides
Counties
Underpinning by county
Each county page has the age of its housing from Census 2022, its ground, and the schemes that apply. Compare all 14.
FAQ
Questions people ask
What is underpinning?
Strengthening the foundation of an existing building by making it deeper or wider, so it rests on firmer ground or spreads its load over a bigger area. The main methods are mass concrete, beam and base, mini-piles and injection.
Does my house need underpinning?
Only a chartered structural engineer can say, after looking at the cracks, the ground and the drains. Most cracks don't mean underpinning: BRE's scale treats cracks up to 5 mm as aesthetic.
How much does underpinning cost in Ireland?
No Irish contractor or public body that we could find publishes a price list. The one published Irish figure is €16,000 for mini-piling under a semi-detached house in Dublin 6 in 2020, at trade rates. Your price comes from your engineer's design.
Does home insurance cover subsidence?
The Irish policies we've read list subsidence, ground heave and landslip as insured events, with a separate subsidence excess and a list of exclusions. Check your own booklet.
How long does underpinning take?
It depends on the method and the house. The cracks aren't repaired until six months to a year after the works, so the whole process from first crack to finished repair can run over a year.
Who will ring me?
We pass your request to one experienced groundworks and underpinning contractor who covers your county. Your number isn't sent to a list. They ring you, ask what's happening and about any engineer's report, and price the work from the engineer's design. Nothing is booked until you say yes.
Sources (1)
Prices and facts on this page were checked against these published pages. We are not connected to these businesses.
- Aviva policy conditions: arachas.ie
Get it looked at properly
Five quick questions and one experienced groundworks and underpinning contractor who covers your county rings you. Or call 087 162 1846 between 8am and 8pm.