Cornwall · England
Bay window subsidence repairs in Cornwall
Homes in Cornwall are mostly granite and slate-stone cottages. That matters for bay window subsidence repairs: footings, wall construction and mortar all vary with the age of the building. Clay shrinkage is less of a concern in Cornwall, so other causes such as drains, poor footings or older walls are checked first.
Guide price from£620per bay inc VAT
- Area
- Cornwall
- Pricing region
- South West
- Ground
- Mostly firmer ground
- Towns listed
- 9
What is the ground like in Cornwall?
Cornwall is mostly granite and slate with little shrinkable clay, so clay subsidence is less common than in the south-east. Historic tin and copper mining has left shafts and workings in places such as Camborne and Redruth, and mining searches are routine there.
Old metal-mine shafts and workings are recorded in places, so mining searches are routine for some properties. Housing stock in Cornwall: Granite and slate-stone cottages, cob buildings, Victorian terraces and post-war estates.
How much will bay window subsidence repairs cost in Cornwall?
The ranges below reflect typical South West costs for bay window subsidence repairs, including VAT. Scaffold, access and making good can push a job to the top of the range.
| 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 Cornwall?
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
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
What happens when we carry out bay window subsidence repairs in Cornwall?
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.
Signs you may need bay window subsidence repairs
- A step or slope in the bay floor towards the window
- Cracks above the bay window head or below the sill
- A vertical crack where the bay meets the front wall
- Bay window sash or casement sticking or binding
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.
Towns in Cornwall we cover for bay window subsidence repairs
Bay window subsidence repairs in Cornwall: questions and answers
Is the ground in Cornwall prone to subsidence?
Cornwall is mostly granite and slate with little shrinkable clay, so clay subsidence is less common than in the south-east. Historic tin and copper mining has left shafts and workings in places such as Camborne and Redruth, and mining searches are routine there. Old metal-mine shafts and workings are recorded in places, so mining searches are routine for some properties. Only an investigation on site can say why a particular building has moved.
How much will bay window subsidence repairs cost in Cornwall?
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.
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.
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.