Dorset · England
Bay window subsidence repairs in Dorset
Homes in Dorset are mostly stone and brick villages. That matters for bay window subsidence repairs: footings, wall construction and mortar all vary with the age of the building. Parts of Dorset have clay that can shrink near trees in dry spells.
Guide price from£620per bay inc VAT
- Area
- Dorset
- Pricing region
- South West
- Ground
- Clay in parts
- Towns listed
- 7
What should you know about the ground under Dorset?
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.
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.
How much will bay window subsidence repairs cost in Dorset?
Guide prices below are for homes in Dorset, on South West rates and including VAT. A survey or good photos let us turn them into a fixed written price.
| 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 |
Which repair method suits a home in Dorset?
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
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
What happens when we carry out bay window subsidence repairs in Dorset?
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.
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.
Signs you may need bay window subsidence repairs
- 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
- Cracks above the bay window head or below the sill
Do you need approval 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.
Find bay window subsidence repairs in your Dorset town
Bay window subsidence repairs in Dorset: questions and answers
Why do houses in Dorset crack?
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. Ground movement here is more often linked to soils, drains and trees than to mining. Only an investigation on site can say why a particular building has moved.
How much will bay window subsidence repairs cost in Dorset?
On South West rates, bay window subsidence repairs starts from about £620 per bay, including VAT. The written price depends on the extent of the damage, access and whether an engineer or building control is needed.
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.
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.