Extension pulling away repairs in Hertfordshire

Area: Hertfordshire
Pricing region: East of England
Ground: Shrinkable clay widespread
Towns listed: 19

Is Hertfordshire prone to ground movement?

Ground movement here is more often linked to soils, drains and trees than to mining. Across Hertfordshire, most homes are garden-city houses in Letchworth and Welwyn, 1930s semis, Victorian terraces and post-war new-town estates.

What should you budget for extension pulling away repairs in Hertfordshire?

The ranges below reflect typical East of England costs for extension pulling away repairs, including VAT. Scaffold, access and making good can push a job to the top of the range.

Guide prices inc VAT on East of England rates. Items marked est. are our estimates.
Item	Guide price	Per
Junction crack repair with stainless tiesest.	£630 – £2,100	per junction
Movement joint and making goodest.	£420 – £1,250	per junction
Underpinning the extension where needed	£1,050 – £2,600	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

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 to expect when we carry out extension pulling away repairs

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.

Is it time for extension pulling away repairs? Common signs

Daylight or draughts showing through the internal corner joint
Mastic or render at the joint repeatedly splitting open
A vertical crack or gap where the extension meets the house
Patio doors or windows in the extension starting to bind

Extension pulling away: tapered gap at the junction tied in with stainless bars. Indicative drawing, not to scale.

Do you need approval 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 near you in Hertfordshire

Your extension pulling away repairs questions

Does the ground around Watford cause cracking?

South Hertfordshire around Watford, Borehamwood and Potters Bar is London Clay, while the north and west are chalk with clay-with-flints and the east has boulder clay. The clay areas are prone to seasonal subsidence near trees. Ground movement here is more often linked to soils, drains and trees than to mining. Only an investigation on site can say why a particular building has moved.

How much will extension pulling away repairs cost in Hertfordshire?

On East of England rates, extension pulling away repairs starts from about £630 per junction, including VAT. The written price depends on the extent of the damage, access and whether an engineer or building control is needed.

Who is responsible if a recent extension is moving?

If the extension is recent, the original builder, the designer or building control records may be relevant, and you may have rights against the builder. Gather the plans, completion certificate and contract. Insurance often excludes defects in new construction, so check your policy.

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.

What is a movement joint?

A movement joint is a deliberate, flexible break in a wall that lets two parts of a building move slightly without cracking. It is filled with a compressible material and sealed. At an extension junction it can replace a rigid joint that keeps cracking.