Lewisham · Greater London
Extension pulling away repairs in Lewisham
The ground under Lewisham 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
- BR3, SE4, SE6, SE12, SE13
- Population
- about 300,000
- Area
- Greater London
- Pricing region
- London
How do local ground conditions affect extension pulling away repairs in Lewisham?
We cover the whole of Lewisham, including postcode districts BR3, SE4, SE6, SE12, SE13; about 300,000 people live in the borough. We also take enquiries from nearby Southwark (3 miles), Greenwich (4 miles) and Lambeth (4 miles).
Greater London 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 Greater London: Victorian and Edwardian terraces with shallow footings, inter-war semis in the outer boroughs, and converted flats and mansion blocks.
What happens when we carry out extension pulling away repairs in Lewisham?
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.
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.
Signs you may need extension pulling away repairs
- Mastic or render at the joint repeatedly splitting open
- Patio doors or windows in the extension starting to bind
- Floor level dropping where the extension and house floors meet
How much will extension pulling away repairs cost in Lewisham?
For Lewisham we use London 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. | £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 |
Which repair method suits a home in Lewisham?
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
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
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 Lewisham: questions and answers
How much should I budget for extension pulling away repairs in Lewisham?
Guide prices for extension pulling away repairs in Lewisham 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 Lewisham?
Yes, Lewisham is covered, along with postcode districts BR3, SE4, SE6, SE12. We also cover nearby Southwark and Greenwich.
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.
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 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.
Related work in Lewisham
- Boundary and garden wall repairs
- Structural crack repairs
- Bay window subsidence repairs
- Bowing wall repairs
- Resin injection ground stabilisation
Extension pulling away repairs near Lewisham
Call about the cracked extension junction at your Lewisham property; a free initial assessment first, then a fixed written price once the repair is specified.