Weymouth · Dorset
Bay window subsidence repairs in Weymouth
A cracked bay in Weymouth can be anything from an old, stable joint to a foundation that is still dropping. Photos of the outside junction and the inside corners usually show which is more likely and whether an engineer should look.
Guide price from£620per bay inc VAT

- Postcodes
- DT3, DT4
- Population
- about 53,000
- Area
- Dorset
- Pricing region
- South West
What should you know about the ground under Weymouth?
Weymouth (DT3, DT4) has around 53,000 residents and sits in Dorset. If you are just outside Weymouth, we also cover Dorchester (7 miles), Poole (22 miles) and Yeovil (24 miles).
Parts of Dorset 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. Typical buildings in Dorset: Stone and brick villages, Victorian villas in Bournemouth, and inter-war and post-war semis.
Methods for bay window subsidence repairs
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
From first photo to finished repair
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.
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.
Symptoms that point to bay window subsidence repairs
- Bay window sash or casement sticking or binding
- A step or slope in the bay floor towards the window
- Gaps opening around the internal bay window board
Guide prices for bay window subsidence repairs in Weymouth
Prices in Weymouth are worked out on South West rates. They include VAT and are a starting point: access, the extent of the damage and whether an engineer or building control is involved all move the figure.
| 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 |
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
What is the price of bay window subsidence repairs in Weymouth?
Guide prices for bay window subsidence repairs in Weymouth 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 Weymouth?
We do. Weymouth and the surrounding area are covered, including nearby Dorchester and Poole. A free initial assessment from your photos is the first step.
Does the ground around Weymouth cause cracking?
Dorset mixes chalk downs, Oxford and Kimmeridge Clays in the vales, and the sands and gravels of the Poole basin. Clay vales can shrink and swell, and parts of the coast are known for landslip. Only an investigation can say why a particular building has moved.
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.
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.
More repairs we carry out in Weymouth
- Structural crack repairs
- Underpinning
- Resin injection ground stabilisation
- Lintel replacement
- Boundary and garden wall repairs
Bay window subsidence repairs near Weymouth
If your insurer is handling a bay claim at your Weymouth property, share the schedule and we will price the repair to it in writing.