Chippenham · Wiltshire
Bay window subsidence repairs in Chippenham
If your Chippenham bay window has started sticking and a gap has opened at the junction, it is worth finding out whether the bay is still moving. A stable crack needs a straightforward tie-in, whereas an active one may need a new foundation.
Guide price from£620per bay inc VAT

- Postcodes
- SN14, SN15
- Population
- about 36,000
- Area
- Wiltshire
- Pricing region
- South West
What should you know about the ground under Chippenham?
Postcode districts SN14, SN15 cover Chippenham, a Wiltshire town of about 36,000 people. Nearby, we also cover Calne (5 miles), Melksham (6 miles) and Devizes (9 miles).
Wiltshire 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 Wiltshire: stone cottages, railway terraces in Swindon, and large post-war and new-build estates.
Guide prices for bay window subsidence repairs in Chippenham
These are guide prices for Chippenham, using South West rates and including VAT. Your written quote follows photos or a survey, and is fixed once the repair is specified.
| 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 |
Methods for bay window subsidence repairs
Traditional underpinning of the bay
The bay footing is excavated in short sections and new mass concrete is placed down to firmer ground below the zone affected by roots and seasons. Because a bay is a short length of wall, the work is compact, but it needs building control approval.
Best for: Active bay movement on firm ground at moderate depth
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
From first photo to finished repair
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.
Agree the repair
The engineer decides between tie-in repairs and underpinning. We confirm a fixed price in writing once the repair is specified, including scaffolding if needed, the bay window, roof flashing and internal making good.
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.
Symptoms that point to bay window subsidence repairs
- Bay roof or lead flashing pulling away from the main wall
- A step or slope in the bay floor towards the window
- A vertical crack where the bay meets the front wall
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.
Frequently asked questions
How much will bay window subsidence repairs cost in Chippenham?
Guide prices for bay window subsidence repairs in Chippenham 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 cover Chippenham?
Yes, Chippenham is covered, along with postcode districts SN14, SN15. We also cover nearby Calne and Melksham.
Is the ground in Wiltshire prone to subsidence?
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.
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.
Can I just fill the crack myself?
Filling it hides the evidence without dealing with the cause, and if the bay is still moving the crack will reopen. Photograph it with a scale and date first. If you plan to claim on insurance, tell your insurer before any repair, including filling.
Other structural repairs in Chippenham
- Extension pulling away repairs
- Roof structure repairs
- Crack stitching
- Resin injection ground stabilisation
- Underpinning
Bay window subsidence repairs near Chippenham
Call about the cracked bay at your Chippenham property; a free initial assessment comes first, with a fixed written price once the repair is specified.