Barnet · Greater London
Extension pulling away repairs in Barnet
The ground under Barnet and Greater London varies street by street, and extensions built on shallower footings feel those differences first. A trial pit and a drain survey usually tell an engineer how the extension’s foundation is coping.
Guide price from£750per junction inc VAT
- Postcodes
- EN4, EN5, N3, N12, N20
- Population
- about 390,000
- Area
- Greater London
- Pricing region
- London
Is Greater London prone to ground movement?
We cover the whole of Barnet, including postcode districts EN4, EN5, N3, N12, N20; about 390,000 people live in the borough. Nearby, we also cover Haringey (4 miles), Borehamwood (4 miles) and Potters Bar (5 miles).
Much of Greater London 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 Greater London, most homes are Victorian and Edwardian terraces with shallow footings, inter-war semis in the outer boroughs, and converted flats and mansion blocks.
What should you budget for extension pulling away repairs in Barnet?
These are guide prices for Barnet, using London 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. | £750 – £2,500 | per junction |
| Movement joint and making goodest. | £500 – £1,500 | per junction |
| Underpinning the extension where needed | £1,250 – £3,100 | per metre of wall |
Repair options we may recommend
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
Movement joint and making good
Where some seasonal movement is expected to continue, the junction is formed into a proper flexible movement joint with a compressible filler and sealant, so the two parts can move without cracking. Flashings and internal finishes are detailed to suit.
Best for: Minor ongoing movement that does not threaten the structure
What to expect when we carry out extension pulling away repairs
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.
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.
Is it time for extension pulling away repairs? Common signs
- A vertical crack or gap where the extension meets the house
- Floor level dropping where the extension and house floors meet
- Extension roof flashing lifting off the original 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.
Your extension pulling away repairs questions
How much should I budget for extension pulling away repairs in Barnet?
Guide prices for extension pulling away repairs in Barnet start from about £750 per junction, 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 Barnet?
We do. Barnet and the surrounding area are covered, including nearby Haringey and Borehamwood. A free initial assessment from your photos is the first step.
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.
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.
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.
Related work in Barnet
- Floor joist repairs
- Subsidence repairs
- Chimney stack repairs
- Subsidence insurance claim repairs
- Bay window subsidence repairs
Extension pulling away repairs near Barnet
For a no-obligation written quote to repair an extension pulling away in Barnet, call or send a few photos with a tape measure across the gap.