Westbury · Wiltshire
Bay window subsidence repairs in Westbury
Repairing a subsiding bay in Westbury usually involves one of three routes: tie the junction, underpin with concrete, or install mini-piles. The engineer picks the route from the ground and the movement history, and we price it in writing.
Guide price from£620per bay inc VAT

- Postcodes
- BA13
- Population
- about 17,000
- Area
- Wiltshire
- Pricing region
- South West
Is Wiltshire prone to ground movement?
Westbury is in Wiltshire and takes in postcode districts BA13. About 17,000 people live there. Nearby places we cover include Warminster (4 miles), Trowbridge (4 miles) and Frome (6 miles).
Parts of Wiltshire have clay that can shrink near trees in dry spells. Ground movement here is more often linked to soils, drains and trees than to mining. What you mostly find across Wiltshire: stone cottages, railway terraces in Swindon, and large post-war and new-build estates.
What to expect when we carry out bay window subsidence repairs
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.
Carry out the work
Ties are fitted across the junction, or the bay is underpinned in sequence with building control inspecting the dig. The bay window and flashings are checked and eased or resealed where the movement has disturbed them.
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
- Cracks above the bay window head or below the sill
- Bay window sash or casement sticking or binding
What should you budget for bay window subsidence repairs in Westbury?
For Westbury we use South West 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. | £620 – £1,850 | per bay |
| Traditional underpinning of a bay | £3,100 – £7,200 | per bay |
| Mini-piled bay underpinning | £5,150 – £12,400 | per bay |
Repair options we may recommend
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
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
Rules for bay window subsidence repairs in England
In England, underpinning and other work that alters or strengthens a wall or foundation is building work under the Building Regulations (Part A, structure), so building control approves and inspects it. Like-for-like repairs often are not, and we tell you which applies before a price is agreed. Work to a party wall, or excavation close to a neighbour’s foundations, can also need a notice under the Party Wall etc. Act 1996.
Your bay window subsidence repairs questions
What is the price of bay window subsidence repairs in Westbury?
Guide prices for bay window subsidence repairs in Westbury start from about £620 per bay, including VAT, on South West rates. Your fixed written price follows photos or a survey and depends on the extent of the work and access.
Do you carry out bay window subsidence repairs in Westbury?
We do. Westbury and the surrounding area are covered, including nearby Warminster and Trowbridge. A free initial assessment from your photos is the first step.
Does the ground around Westbury cause cracking?
Southern Wiltshire is chalk, while the north around Swindon, Chippenham and Trowbridge sits on Oxford and Kimmeridge Clays that are prone to seasonal movement near trees. Bath stone was mined underground around Corsham. Only an investigation can say why a particular building has moved.
Why do bay windows crack away from the house?
Bays often stand on shallower footings than the main walls, so they react to drying clay, roots and drain leaks that the deeper house foundations escape. Many bays were also never properly tied in, so any movement opens a clean vertical crack at the junction.
Can a bay be underpinned without underpinning the house?
Yes, underpinning only the bay is common because it is usually the part on shallower footings. The engineer designs the junction so the strengthened bay and the existing house can move slightly without cracking, sometimes with a movement joint or ties.
More repairs we carry out in Westbury
- Lintel replacement
- Concrete repairs
- Resin injection ground stabilisation
- Wall tie replacement
- Boundary and garden wall repairs
Bay window subsidence repairs near Westbury
Photos of the bay floor, window and junction crack are enough to start; send them about your Westbury home and we will reply with a view.