Banstead · Surrey
Extension pulling away repairs in Banstead
Rear and side extensions are common across Banstead, and so is the crack where new meets old. Usually it reflects the two parts sitting on different foundations, and the first question is whether the gap is still opening.
Guide price from£670per junction inc VAT

- Postcodes
- KT17, SM2, SM7
- Population
- about 46,000
- Area
- Surrey
- Pricing region
- South East
What is the ground like in Surrey?
With roughly 46,000 people, Banstead spans postcode districts KT17, SM2, SM7 in Surrey. If you are just outside Banstead, we also cover Ewell (3 miles), Sutton (3 miles) and Croydon (6 miles).
Much of Surrey sits on clay that shrinks in dry summers and swells in wet winters. Ground movement here is more often linked to soils, drains and trees than to mining. Across Surrey, most homes are Victorian and Edwardian villas, 1930s semis and detached houses in the commuter towns, and post-war estates.
Which repair method suits a home in Banstead?
Underpinning the extension
If the extension is still dropping because its footings are too shallow or on poor ground, they are taken deeper by mass concrete, beam-and-base or mini-piles. The engineer designs the scheme, and the junction is repaired once the new foundation is in.
Best for: Active movement from shallow footings, roots or soft ground
Junction crack repair with stainless ties
The open joint is cut out, stainless ties or helical bars are fixed across it into both the old and new masonry, and the joint is repointed or rendered to match. Inside, the corner is replastered. This suits extensions that moved once and have since stopped.
Best for: Settled extensions with a stable gap at the junction
What happens when we carry out extension pulling away repairs in Banstead?
Find what is moving
An independent chartered structural engineer can inspect, and we can arrange one. A drain survey under the extension, a trial pit at its footing and tell-tale monitoring across the joint are common checks before choosing the repair.
Choose the fix
The engineer decides between ties, a movement joint or underpinning. We confirm a fixed price in writing once the repair is specified, covering the junction, flashings, internal finishes and any foundation work.
Finish and hand over
Internal corners are replastered, skirtings and coving refixed, and doors or windows in the extension eased where the movement affected them. Records of the repair and any approvals are passed to you.
Signs you may need extension pulling away repairs
- A vertical crack or gap where the extension meets the house
- Floor level dropping where the extension and house floors meet
- Patio doors or windows in the extension starting to bind
How much will extension pulling away repairs cost in Banstead?
These are guide prices for Banstead, using South East rates and including VAT. Your written quote follows photos or a survey, and is fixed once the repair is specified.
| Item | Guide price | Per |
|---|---|---|
| Junction crack repair with stainless tiesest. | £670 – £2,250 | per junction |
| Movement joint and making goodest. | £450 – £1,350 | per junction |
| Underpinning the extension where needed | £1,100 – £2,800 | per metre of wall |
Rules for extension pulling away 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.
Extension pulling away repairs in Banstead: questions and answers
How much will extension pulling away repairs cost in Banstead?
Guide prices for extension pulling away repairs in Banstead start from about £670 per junction, including VAT, on South East rates. Your fixed written price follows photos or a survey and depends on the extent of the work and access.
Do you cover Banstead?
Yes. We take enquiries from across Banstead, including KT17, SM2, SM7, and from nearby places such as Ewell and Sutton. Send photos for a free initial view and we will tell you what happens next.
Is the ground in Surrey prone to subsidence?
North Surrey sits on London Clay, the south on Weald Clay, with chalk along the North Downs and sands in the west. Large gardens with mature trees on clay make seasonal subsidence a familiar problem. Only an investigation can say why a particular building has moved.
Can a drain under my extension cause it to move?
Yes, a cracked or displaced drain beneath or beside an extension can soften clay or wash away fine soil. A CCTV drain survey usually finds it. Repairing the drain is often the first and most important step before any repair to the walls.
Can I just fill the gap with mastic?
Mastic can keep water out short term, but it does not stop movement or reconnect the walls. If the gap reopens after filling, something is still moving. Photograph and measure it over a few months first, so an engineer can see the trend.
Other structural repairs in Banstead
- Subsidence insurance claim repairs
- Wall tie replacement
- Subsidence repairs
- Bay window subsidence repairs
- Crack stitching
Extension pulling away repairs near Banstead
Share the loss adjuster’s schedule for your Banstead extension claim, and we will price the junction repair and making good to it in writing.