Caernarfon · Gwynedd
Underpinning in Caernarfon
Before any underpinning goes ahead on a Caernarfon property, building control has to approve the design and inspect the excavations. Where the wall is shared, party wall notices may be needed too in England and Wales, so allow time for paperwork before the dig.
Guide price from£920per metre of wall inc VAT
- Postcodes
- LL55
- Population
- about 10,000
- Area
- Gwynedd
- Pricing region
- Wales
Why does the ground in Gwynedd matter for underpinning?
We cover Caernarfon and its postcode districts LL55, part of Gwynedd, with a population of roughly 10,000. If you are just outside Caernarfon, we also cover Llangefni (8 miles), Bangor (9 miles) and Pwllheli (18 miles).
Clay shrinkage is less of a concern in Gwynedd, so other causes such as drains, poor footings or older walls are checked first. Old metal-mine shafts and workings are recorded in places, so mining searches are routine for some properties. Housing stock in Gwynedd: Slate and stone terraces, chapels and cottages, Victorian seaside houses and post-war estates.
Methods for underpinning
Beam-and-base underpinning
A reinforced concrete beam is cast beneath or alongside the existing footing and carries the wall onto mass concrete bases at intervals. It spreads load well across variable ground and can mean less digging than continuous underpinning along the whole wall.
Best for: Longer runs of wall or heavier loads over variable ground
Mass concrete underpinning
The traditional method. Short sections under the wall are dug out in a set sequence, usually about a metre at a time, and filled with concrete before the next section is opened. It suits moderate depths and good access, and it needs little specialist plant.
Best for: Shallow failures on firm ground found at moderate depth
From first photo to finished repair
Engineer’s investigation
An independent chartered structural engineer studies the monitoring results, trial pits and soil tests, then decides whether underpinning is needed and which method suits. We can arrange the engineer if you do not already have one.
Fixed written price
With the design in hand we confirm a fixed price in writing, setting out the method, the length of wall, access arrangements and the making good. For insurance work we can price to the loss adjuster’s or engineer’s schedule.
Excavation and concrete
Work runs in the sequence the engineer sets so the wall is never left unsupported over a long length. Building control inspects the excavations before concrete goes in, and each section is dry-packed tight to the footing above.
Symptoms that point to underpinning
- Floors sloping noticeably towards one external wall
- One corner of the house visibly lower than the others
- A large tree nearby that cannot be removed or reduced
Guide prices for underpinning in Caernarfon
Guide prices below are for homes in Caernarfon, on Wales rates and including VAT. A survey or good photos let us turn them into a fixed written price.
| Item | Guide price | Per |
|---|---|---|
| Mass-concrete underpinning | £920 – £1,400 | per metre of wall |
| Beam-and-base underpinning | £1,400 – £2,300 | per metre of wall |
| Mini-piled underpinning | £1,850 – £3,200 | per metre of wall |
| Engineer's design and building control feesest. | £735 – £2,300 | per scheme |
Rules for underpinning in Wales
In Wales, the Welsh version of the Building Regulations applies. Underpinning and other work that alters or strengthens the structure needs building control approval and inspection; like-for-like repairs often do not. The Party Wall etc. Act 1996 applies to work on party walls and excavation close to a neighbour’s foundations.
Frequently asked questions
What is the price of underpinning in Caernarfon?
Guide prices for underpinning in Caernarfon start from about £920 per metre of wall, including VAT, on Wales rates. Your fixed written price follows photos or a survey and depends on the extent of the work and access.
Do you carry out underpinning in Caernarfon?
We do. Caernarfon and the surrounding area are covered, including nearby Llangefni and Bangor. A free initial assessment from your photos is the first step.
Does the ground around Caernarfon cause cracking?
Gwynedd and Anglesey are mostly hard rock with glacial deposits, so clay shrinkage is uncommon. Historic slate quarrying and metal mining have left tips and workings in places. Only an investigation can say why a particular building has moved.
Can I stay in my house during underpinning?
Most people stay at home during external underpinning, because the digging happens outside along the wall. Expect noise, restricted access to that side of the house and some dust. If the work has to be done from inside, through the floor, moving out for part of the job is sometimes advised.
Do I need to tell my neighbours about underpinning?
In England and Wales you usually do. Underpinning a party wall normally needs two months’ notice, and excavating near a neighbour’s foundations needs one month’s notice under the Party Wall etc. Act 1996. Scotland and Northern Ireland have no equivalent Act, but agreeing the work in writing still helps.
More repairs we carry out in Caernarfon
- Structural crack repairs
- Subsidence insurance claim repairs
- Brick arch repairs
- Crack stitching
- Bay window subsidence repairs
Underpinning near Caernarfon
For a no-obligation written quote on underpinning in Caernarfon, send photos of the cracking and any engineer’s report you already hold.