Traditional mass-concrete and reinforced underpinning to enable basement excavation beneath your existing London home, designed with your structural engineer, executed by directly-employed labour, warranted for 25 years.
150+ basements excavated · Temporary Works Co-ordinator on team · £10M all-risks insurance.
Underpinning is the controlled extension of your existing foundations downwards to a new, deeper bearing level, creating the structural envelope for a basement. It is planned, sequenced, propped and cast in a strict order, because it is the discipline that keeps a London terrace standing while the ground beneath it is removed.
Engineer-designed underpinning of load-bearing walls in sequenced 'pins', including temporary works, propping, excavation, formwork, reinforcement, concrete pour and cure, carried out under a live building.
Homeowners undertaking a basement excavation or extension, and property owners whose existing foundations require strengthening due to subsidence, adjacent works or change of use.
Whenever a habitable basement is being excavated beneath an existing home, and in remedial situations where foundations have moved or been undermined.
Underpinning is where the structural risk of the whole basement project sits. It is not a general-builder discipline. It is the difference between a basement that lasts 100 years and one that cracks in eighteen months.
Every UHM project runs through the same structured stages. You'll always know what's happening next, who's doing it and when it completes.
Your engineer's underpinning drawings reviewed and converted into a buildable sequence with our Temporary Works Co-ordinator.
Needle-and-prop scheme installed to engineered design. Party wall access agreed. Deliveries and muck-away routed.
Pins excavated by hand in a strict engineer-approved sequence, never adjacent. Each pin propped, cleared and dry before pour.
Rebar cages placed to engineer spec, formwork checked and concrete poured to the correct mix. Cured before the next pin in sequence.
Engineer inspection at hold points, party wall surveyor sign-off where required, structural warranty issued on completion.
Every underpin is site-specific. Here is the technical toolkit we use, and how each method maps to your foundations, neighbours and programme.
The classic London-terrace underpinning method, hand-dug pins, mass concrete pours, sequenced to leave adjacent ground supported at all times. Reliable, cost-effective and the default choice for the majority of Victorian and Edwardian houses.
Where excavation depth exceeds mass-concrete practicalities, reinforced concrete pins carry load with steel reinforcement. Used for deeper basements and where cantilever design is required at party walls.
For basements below the water table, adjacent to deep-founded neighbours or on constrained plots, piled retaining walls or hybrid designs may be specified. Specialist piling is coordinated under our direct site management, so the client sees one accountable team.
Not every underpin is for a basement. We also carry out remedial underpinning where an existing home shows subsidence, where a wall has been undermined by adjacent works, or where a change of use requires foundation strengthening. Same discipline, same warranty.
Our team holds Temporary Works Co-ordinator training as standard, the qualification the industry recognises as the underpinning safety baseline.
25-year structural warranty on the completed basement, backed by UHM Ltd trading since 2009.
Both directors hold NVQ Level 6 Site Management. Ghedeon attends every site every day, no absent principals.
Directly-employed labour means pins are excavated and poured to the sequence we quoted, never delayed by another crew's schedule.
Method statements, surveys and access managed to the letter. Neighbours are informed, not surprised.
The best underpinning is the underpinning nobody notices. No cracks, no doors sticking, no story to tell.
You can't see underpinning after it's finished. That's exactly why it's the stage cut most on price and covered up fastest. The consequences of a bad sequence don't appear during the works, they appear the first winter the ground moves.
Underpinning in the wrong sequence, or with insufficient cure time between pins, causes settlement in your walls and the party wall. Once a wall has settled, no amount of remedial work fully returns it.
A party wall crack caused by poorly managed underpinning becomes a party-wall claim, a legal cost and a stalled programme. The insurance disputes take longer than the build.
Propping and needling that isn't engineer-designed is the single largest cause of catastrophic underpinning failure on London sites. Temporary works is a competence, not a job for site improvisation.
Choosing a contractor with no in-house Temporary Works Co-ordinator.
Accepting a fixed price without an engineer-designed sequence drawing.
Skipping party wall method statements to save time.
Pouring pins wider than the sequence design to 'get it done faster'.
Using non-structural mix concrete because it's cheaper on the day.
Removing propping before the engineer signs off.
Straight answers we give on almost every free site visit, cost, timeline, guarantees and what's included.
Underpinning is priced per project: the number depends on depth, method, party wall complexity and access. There are no fixed prices. Site visits and written quotes are free.
Typically three to six months for a standard London terrace basement. Depth, ground conditions and party wall works can extend this. Your programme is confirmed in the written quote.
In most cases the upper floors remain occupied. Access, dust and vibration are managed by an experienced site team, and Ghedeon attends daily to check safety and progress. We'll always be honest if occupation is impractical for your specific project.
Yes. Temporary Works Co-ordinator qualifications are held in-house, a baseline competence for any contractor doing underpinning, and one we take seriously.
The completed basement carries a 25-year structural warranty covering the underpinning and structural elements, backed by Underhouse Management Ltd.
£10,000,000 all-risks insurance covering both public and employers' liability. Documentation is available to your solicitor and party wall surveyor on request.
We support the party wall process by preparing method statements, temporary works designs, drawings and access schedules for the appointed surveyors. The surveyor role itself remains independent.
Sometimes. We survey the failure, review the original engineer's design and the constructed sequence, and give you a written diagnosis. Where remedy is viable, we scope it; where it isn't, we say so.
A director will visit, review your engineer's drawings, and issue a written quote, for free. If your project needs a different structural approach, we'll tell you.
