Process · checked 29 October 2026
The underpinning process, step by step
Ten steps from the first crack to the engineer's sign-off, with who does what and the rules that apply.
Facts on this page checked against each source on 29 October 2026. Each one links to its source. How we check
Underpinning a house runs in a set order: record the damage, get a chartered structural engineer, find the cause, monitor if needed, design the repair, sort out the insurer, building control, safety duties and neighbours, do the works, let the house settle, then repair the cracks and keep the paperwork.
- Step 1
Record the damage
Photograph and date every crack, inside and out, with a ruler in the shot. Don't fill them: filling cracks is the last thing you do (Irish Examiner, 2022).
- Step 2
A chartered structural engineer assesses it
Engineers Ireland awards the Chartered Engineer title, CEng MIEI (Engineers Ireland). The Health and Safety Authority suggests checking membership of bodies such as Engineers Ireland and the Association of Consulting Engineers when you pick a designer (HSA). The engineer grades the cracks on the BRE scale and reads their pattern to work out whether it's settlement or subsidence (The Irish Times, 2020).
- Step 3
Find the cause
Drains are the usual cause, so they get checked first: before buying a house with cracks, a surveyor told The Irish Times, a detailed drainage survey is essential. A ground investigation with trial holes shows how far down firm ground is. In 2020 an engineer put the ground investigation at around €3,000 (The Irish Times, 2020). For soft or loose ground, the Building Regulations guidance says a site investigation is essential (TGD A).
- Step 4
Monitor, if the engineer asks
Crack monitors fixed across cracks for six to 12 months show whether they're still opening. If they are, the movement is recent (The Irish Times, 2020).
- Step 5
The engineer designs the repair
Method, depth and extent: see underpinning methods. For existing buildings, TGD A notes that guidance written for new work may be unduly restrictive or impracticable, and that approaches based on its principles may be more relevant (TGD A).
- Step 6
Insurer, building control and neighbours
Insurer: tell them as soon as reasonably possible and give full details within 30 days (Aviva policy conditions). See subsidence insurance.
Building control: a Commencement Notice is required for, among other things, a material alteration of a building, and is not required for works that need neither planning permission nor a Fire Safety Certificate. Where one is needed, it goes to the council 14 to 28 days before work starts, and starting without one is an offence (Dún Laoghaire-Rathdown guide). Ask your engineer which applies to your job.
Neighbours: for a shared wall, the Land and Conveyancing Law Reform Act 2009 lets you carry out works to a party structure, including repair and strengthening, if you make good any damage and pay the neighbour's reasonable costs of professional advice and compensation for inconvenience. If they refuse, the District Court can make a works order (s. 43, s. 44, s. 45).
- Step 7
Your safety duties as the client
When you have building work done, you are the client. You must use competent people, and appoint project supervisors for design (PSDP) and construction (PSCS) where there is more than one contractor, a particular risk, or work lasting more than 30 days. The HSA lists deep excavations in poor soil as a particular risk (HSA). Your designer and contractor are obliged to tell you if project supervisors are needed.
- Step 8
The works
In a typical Irish drain-led repair: the old clay drains and affected soil are dug out, the ground under the foundations is stabilised, new uPVC drains go in on drainage aggregate and are tested, and the ground is reinstated (Irish Examiner, 2022).
- Step 9
Let it settle, then repair the cracks
After six months to a year for any remaining settlement to work itself out, the cracks are filled and doors eased (Irish Examiner, 2021).
- Step 10
Sign-off and records
An engineer or architect signing off the work is essential if you want to sell later, and a buyer's bank will want to see the reports and costs (The Irish Times, 2020). Keep the engineer's report and design, the drain survey, the sign-off, photos and VAT invoices. Insurers can hold back part of a settlement until they see the invoices (Aviva).
Start with a chartered structural engineer. Nobody can tell from a photo or a phone call whether a house needs underpinning. An engineer looks at the cracks, the ground and the drains, then decides. This site never tells anyone their house is safe or unsafe.
Who does what
| Role | Who | What they do |
|---|---|---|
| Client | You, the homeowner | Hires competent people, appoints project supervisors where needed, keeps the safety file |
| Structural engineer | A chartered engineer you appoint (or the insurer's) | Assesses, investigates, designs, inspects and signs off |
| PSDP and PSCS | Normally the designer and the contractor, if competent | Coordinate safety in design and on site |
| Groundworks and underpinning contractor | The firm that prices and builds the design | Excavation, drains, underpinning, reinstatement |
| Insurer | If you're claiming | Agrees the claim, may arrange the repair through its own contractors |
Sources: HSA; Aviva; Bank of Ireland home insurance summary.
Questions people ask
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.
Do I need a Commencement Notice for underpinning?
It depends on the works. Notices are required for material alterations, among other things, and not required for works needing neither planning permission nor a Fire Safety Certificate. Ask your engineer, and lodge it 14 to 28 days before starting if one is needed.
Do I need my neighbour's permission to underpin a party wall?
The Land and Conveyancing Law Reform Act 2009 gives you a right to carry out works to a party structure, with duties to make good damage and pay the neighbour's reasonable costs of advice. If they refuse, you can apply to the District Court for a works order.
Who should design the underpinning?
A chartered structural engineer. Engineers Ireland awards the CEng MIEI title. The HSA suggests checking membership of bodies such as Engineers Ireland or the Association of Consulting Engineers.
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 (2)
Prices and facts on this page were checked against these published pages. We are not connected to these businesses.
- Aviva policy conditions: arachas.ie
- Bank of Ireland home insurance summary: personalbanking.bankofireland.com
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.