We carry out engineer-designed underpinning and subsidence repairs in Childwall, L16. Most of the homes here are inter-war and post-war semis and detached houses, and extensions are very common, so many of the cracks we are asked about sit at the joint between the original house and later additions. That often points to an extension issue rather than failing main foundations.
Where old meets new
Childwall, in L16 and within Liverpool City Council’s area, is largely 20th-century housing that has been added to over the years: rear kitchens, side extensions, garage conversions and conservatories. Each addition sits on its own foundation, built to the standards and ground conditions its builder found at the time. Where that foundation is shallower than the house or sits on different ground, the junction can open, tilt or crack.
Our page on extension subsidence repair sets out the usual causes and repair routes. In brief, the engineer looks at the extension’s footing, nearby trees and drains, and whether the crack is moving, before anything is designed.
Steps after you ring us
- Talk it through. We ask where the cracking is, when you noticed it, whether doors in the extension now stick, and when the extension was built.
- Visit. We look at the junction, the extension walls and floor, gullies, downpipes and any trees.
- Investigate if needed. A structural engineer may recommend trial pits to expose the footing, a CCTV drain survey or a period of monitoring.
- Agree a repair. That might be drain repair and crack repair, partial underpinning of the extension, or rebuilding a poorly founded section, all to the engineer’s design.
- Do the work in stages, with Building Control involved and sign-off at the end as applicable.
Floors, not just walls
Sometimes it is the floor that moves. A solid ground floor laid on fill that was not compacted properly can drop away from the skirting while the walls stay put. That calls for a different repair from underpinning, and it is worth ruling out early. See sinking floor repair for more.
On a semi, work near the shared wall usually means the Party Wall etc. Act 1996 needs to be considered. A party wall surveyor handles the notices; we are not party wall surveyors and do not give legal advice.
Thinking about costs
Extension repairs vary widely, depending on whether the cause is a drain, a tree or a poor footing, how deep firm ground is, access to the back of the house and how much making good is needed inside. Our cost guide covers those factors in more detail.
Nearby
Childwall sits between Wavertree, Old Swan and Woolton, all of which we cover. Find out more about Liverpool underpinning and foundation repair, or how we handle underpinning across the city, on our homepage.
Crack at your Childwall extension?
Phone 07777 659786 and tell us when the extension was built and what you have noticed. We will call back and suggest what should be looked at first.
Frequently asked questions
Why has a crack opened where my extension meets the house?
Extensions are often built on different, and sometimes shallower, foundations from the original house, so the two parts can move slightly differently. That can open a vertical crack at the junction. It may be minor and stable, or a sign of ongoing movement in the extension. A structural engineer needs to inspect before any decision about underpinning.
My solid floor seems to be sloping. Is that subsidence?
It can be, but a sloping or sinking ground floor often comes from the floor slab itself, for example poorly compacted fill beneath it, rather than the walls’ foundations. The engineer tells the two apart. Our sinking floor repair page explains the possibilities.
Will underpinning the extension sort the problem for good?
Only if underpinning suits the cause. If a drain is leaking or a tree is drying the ground, those need dealing with first. Where the extension is underpinned, the engineer also designs for how the stiffer section will behave next to the original house, as differential movement at the junction is a known risk.
I want to build another extension. Should I check anything first?
If there are existing cracks, get a structural engineer’s view before starting, and do not begin building or tree work without advice. Nearby trees and drains affect the foundation design for any new work, and Building Control will need to approve it.
Do I have to tell my insurer about cracking?
If you suspect subsidence, contact your buildings insurer first. The insurer and its loss adjuster decide on investigation, monitoring and repair. We can explain the process and carry out a scheme they agree, but we cannot say whether a claim will be accepted.