Dartford · Kent
Extension pulling away repairs in Dartford
If the corner joint in your Dartford 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
- DA1
- Population
- about 51,000
- Area
- Kent
- Pricing region
- South East
What is the ground like in Kent?
Dartford (DA1) has around 51,000 residents and sits in Kent. We also take enquiries from nearby Bexley (3 miles), Swanley (4 miles) and Swanscombe (4 miles).
Shrinkable clay is widespread in Kent. Parts of Kent lie on a former coalfield, so a coal mining search is worth checking if movement has no obvious cause. What you mostly find across Kent: Victorian terraces in the Medway towns, weatherboarded and Wealden houses, 1930s semis and seaside bungalows.
What to look for before calling about extension pulling away repairs
- Extension roof flashing lifting off the original wall
- Floor level dropping where the extension and house floors meet
- A vertical crack or gap where the extension meets the house
Extension pulling away repairs prices in Dartford
For Dartford we use South East rates. Treat the table as a budget guide, inc VAT; the price you pay is the one on your written quote.
| 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 |
How we usually approach extension pulling away repairs
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
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
What happens during extension pulling away repairs, step by step?
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.
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.
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.
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.
Questions about extension pulling away repairs in Dartford
How much will extension pulling away repairs cost in Dartford?
Guide prices for extension pulling away repairs in Dartford 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 Dartford?
We do. Dartford and the surrounding area are covered, including nearby Bexley and Swanley. A free initial assessment from your photos is the first step.
Is the ground in Kent prone to subsidence?
North Kent sits on London Clay, central Kent on Gault and Weald Clays and the Downs on chalk, so shrinkable clay is widespread. East Kent around Deal and Dover had a small deep coalfield, worked until the late 1980s. Only an investigation can say why a particular building has moved.
Will my extension need underpinning?
Often not. Many separating extensions are fixed by repairing a drain, tying the junction or forming a movement joint. Underpinning is for extensions that keep dropping because their footings are too shallow or the ground beneath is poor, as shown by monitoring.
Why is my extension pulling away from my house?
Usually because the extension and the house sit on different foundations that react differently to the ground. Shallow extension footings, leaking drains under the extension, nearby roots and weak tie-ins between old and new walls are the common causes.
Other structural repairs in Dartford
- Structural surveys and crack monitoring
- Resin injection ground stabilisation
- Mining subsidence repairs
- Bowing wall repairs
- Brick arch repairs
Extension pulling away repairs near Dartford
Photos of the crack, the internal corner and the roof flashing are a good start; send them about your Dartford home and we will reply with a view.