Merton · Greater London
Bay window subsidence repairs in Merton
Many bays in Merton were butted against the house rather than bonded into it with ties or toothed brickwork. That makes the junction the first place any differential movement shows, even when the bay foundation is reasonably sound.
Guide price from£750per bay inc VAT
- Postcodes
- CR4, SM4, SW19, SW20
- Population
- about 220,000
- Area
- Greater London
- Pricing region
- London
Is Greater London prone to ground movement?
We cover the whole of Merton, including postcode districts CR4, SM4, SW19, SW20; about 220,000 people live in the borough. Nearby places we cover include Wandsworth (3 miles), Sutton (3 miles) and Kingston upon Thames (4 miles).
Shrinkable clay is widespread in Greater London. Ground movement here is more often linked to soils, drains and trees than to mining. Typical buildings in Greater London: Victorian and Edwardian terraces with shallow footings, inter-war semis in the outer boroughs, and converted flats and mansion blocks.
How we usually approach 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
What happens during bay window subsidence repairs, step by step?
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.
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.
What to look for before calling about bay window subsidence repairs
- Bay window sash or casement sticking or binding
- A step or slope in the bay floor towards the window
- A vertical crack where the bay meets the front wall
Bay window subsidence repairs prices in Merton
The ranges below reflect typical London 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. | £750 – £2,250 | per bay |
| Traditional underpinning of a bay | £3,750 – £8,750 | per bay |
| Mini-piled bay underpinning | £6,250 – £15,000 | 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.
Questions about bay window subsidence repairs in Merton
How much should I budget for bay window subsidence repairs in Merton?
Guide prices for bay window subsidence repairs in Merton start from about £750 per bay, including VAT, on London rates. Your fixed written price follows photos or a survey and depends on the extent of the work and access.
Can you survey a property in Merton?
Yes, Merton is covered, along with postcode districts CR4, SM4, SW19, SW20. We also cover nearby Wandsworth and Sutton.
Why do houses in Greater London crack?
Most of Greater London sits on London Clay, among the most shrinkage-prone ground in the UK, with river gravels along the Thames. Subsidence claims here are among the most frequent in the country, especially after dry summers and near street and garden trees. Only an investigation can say why a particular building has moved.
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.
Does a bay window always need underpinning?
No, many bays are fixed by tying the junction and repointing, once any cause such as a leaking gully is put right. Underpinning is for bays still dropping after the cause has been dealt with, or with footings too shallow for the ground they sit on.
Related work in Merton
- Structural crack repairs
- Wall tie replacement
- Chimney stack repairs
- Structural surveys and crack monitoring
- Boundary and garden wall repairs
Bay window subsidence repairs near Merton
Send photos of the bay junction inside and out at your Merton home for a free initial assessment and a guide price.