Shoreham-by-Sea · West Sussex
Extension pulling away repairs in Shoreham-by-Sea
If the corner joint in your Shoreham-by-Sea extension keeps splitting after you fill it, something is still moving. Measuring the gap over a few months, with dated photos, gives an engineer the evidence to recommend the right repair.
Guide price from£670per junction inc VAT

- Postcodes
- BN42, BN43
- Population
- about 19,000
- Area
- West Sussex
- Pricing region
- South East
What should you know about the ground under Shoreham-by-Sea?
Postcode districts BN42, BN43 cover Shoreham-by-Sea, a West Sussex town of about 19,000 people. Nearby, we also cover Lancing (2 miles), Worthing (5 miles) and Brighton (6 miles).
West Sussex is one of the parts of the UK where clay soils are most likely to move with the seasons. Ground movement here is more often linked to soils, drains and trees than to mining. What you mostly find across West Sussex: Wealden cottages, 1930s semis and bungalows on the coast, and new-town estates in Crawley.
Methods for extension pulling away repairs
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
From first photo to finished repair
Show us the junction
Send photos of the crack outside, the internal corner and any flashing above, with a measure for scale. We give a free initial assessment and an initial view on whether the gap is likely old or still opening.
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.
Repair the junction
Drains are repaired first if they are leaking. The joint is then tied, formed as a movement joint or rebuilt after underpinning, with roof flashings reset so the junction stays watertight. Building control is handled where needed.
Symptoms that point to extension pulling away repairs
- Extension roof flashing lifting off the original wall
- A vertical crack or gap where the extension meets the house
- Daylight or draughts showing through the internal corner joint
Guide prices for extension pulling away repairs in Shoreham-by-Sea
Prices in Shoreham-by-Sea are worked out on South East 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 |
|---|---|---|
| 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.
Frequently asked questions
How much will extension pulling away repairs cost in Shoreham-by-Sea?
Guide prices for extension pulling away repairs in Shoreham-by-Sea 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 Shoreham-by-Sea?
We do. Shoreham-by-Sea and the surrounding area are covered, including nearby Lancing and Worthing. A free initial assessment from your photos is the first step.
Is the ground in West Sussex prone to subsidence?
North West Sussex around Crawley and Horsham sits on Weald Clay, the South Downs are chalk, and the coastal plain has brickearth and gravels. The Weald Clay is prone to shrink-swell movement near trees. Only an investigation can say why a particular building has moved.
Is it normal for an extension to crack at the join?
A fine crack at the junction is fairly common, especially in the first few years as a new extension settles. It becomes a concern when the gap is widening, tapering, letting in water or matched by sticking doors and sloping floors. Those signs point to continuing movement.
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 Shoreham-by-Sea
- Subsidence repairs
- Concrete repairs
- Resin injection ground stabilisation
- Wall tie replacement
- Retaining wall repairs
Extension pulling away repairs near Shoreham-by-Sea
For a no-obligation written quote to repair an extension pulling away in Shoreham-by-Sea, call or send a few photos with a tape measure across the gap.