Cardiff · South Glamorgan
Bay window subsidence repairs in Cardiff
Bay windows are a feature of many older streets in Cardiff, and so is the crack where a bay meets the front wall. Often it reflects a shallower bay footing reacting to the ground, rather than a problem with the whole house.
Guide price from£550per bay inc VAT
- Postcodes
- CF10, CF11, CF24
- Population
- about 370,000
- Area
- South Glamorgan
- Pricing region
- Wales
How do local ground conditions affect bay window subsidence repairs in Cardiff?
Cardiff, South Glamorgan: about 370,000 residents across postcode districts CF10, CF11, CF24. If you are just outside Cardiff, we also cover Penarth (3 miles), Caerphilly (7 miles) and Barry (7 miles).
South Glamorgan has a mix of ground, with clay in some places and firmer rock in others. Ground movement here is more often linked to soils, drains and trees than to mining. What you mostly find across South Glamorgan: Victorian terraces in Cardiff and Penarth, inter-war semis and post-war estates.
What should you budget for bay window subsidence repairs in Cardiff?
For Cardiff we use Wales rates. Treat the table as a budget guide, inc VAT; the price you pay is the one on your written quote.
| Item | Guide price | Per |
|---|---|---|
| Bay junction crack repair and tie-inest. | £550 – £1,650 | per bay |
| Traditional underpinning of a bay | £2,750 – £6,450 | per bay |
| Mini-piled bay underpinning | £4,600 – £11,000 | per bay |
Repair options we may recommend
Mini-piled bay underpinning
Small piles are installed to depth around or beneath the bay and linked by a reinforced beam or needles that pick up its weight. It suits deeper soft ground and heavy root activity, and the compact rigs fit into a front garden.
Best for: Deep clay, nearby trees, or poor ground below the bay
Junction crack repair and tie-in
Where movement has stopped, the open joint between bay and house is raked out, stainless ties or helical bars are fixed across it, and the joint is repointed to match. Internal plaster along the crack is cut back and renewed before redecoration.
Best for: Old, stable cracks where the bay is no longer moving
What to expect when we carry out bay window subsidence repairs
Photos and first view
Send photos of the outside junction, the inside corners and the window, with a scale. We give a free initial assessment and tell you whether the crack looks old and stable or whether an engineer should inspect first.
Engineer and checks
Where the cause is unclear, an independent chartered structural engineer inspects, sometimes with a trial pit at the bay and a drain survey. We can arrange the engineer. Monitoring may be suggested if the movement could be seasonal.
Make good inside
Plaster around the bay and along the junction is renewed, the window board is refixed and the room is ready for decoration. Building control paperwork, where it applies, is passed to you for your records.
Is it time for bay window subsidence repairs? Common signs
- Gaps opening around the internal bay window board
- Bay window sash or casement sticking or binding
- A vertical crack where the bay meets the front wall
Rules for bay window subsidence repairs 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.
Your bay window subsidence repairs questions
How much will bay window subsidence repairs cost in Cardiff?
Guide prices for bay window subsidence repairs in Cardiff start from about £550 per bay, 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 cover Cardiff?
Yes. We take enquiries from across Cardiff, including CF10, CF11, CF24, and from nearby places such as Penarth and Caerphilly. Send photos for a free initial view and we will tell you what happens next.
Is the ground in South Glamorgan prone to subsidence?
Cardiff is built on Mercia Mudstone, river gravels and alluvium, and the Vale of Glamorgan on Lias limestone and clay. Soft alluvium near the rivers and docks can settle. Only an investigation can say why a particular building has moved.
Will the bay window need replacing?
Usually not. Most windows can be eased, packed or resealed once the bay is stable. If the frame has twisted badly or the glass has cracked, replacement may be worth considering. Under a claim, upgrades beyond like-for-like are normally priced separately.
How long does bay underpinning take?
Traditional underpinning of a bay usually takes about a week on site, and mini-piling a little longer depending on depth. A junction tie-in without underpinning normally takes one to two days. Approvals and any monitoring beforehand add to the overall timeline.
Other structural repairs in Cardiff
Bay window subsidence repairs near Cardiff
Photos of the bay floor, window and junction crack are enough to start; send them about your Cardiff home and we will reply with a view.