Planning an extension and need the groundworks and brickwork done properly? MLS Contractors is a CHAS-accredited groundworks and brickwork contractor working across Surrey, Sussex, Kent and London. We build the part of your extension that everyone stops seeing once it is finished — the excavation, the foundations, the drainage and the brick and blockwork shell — and we build it to the standard your building inspector and structural engineer expect.
Extension Groundworks and Brickwork Across Surrey, Sussex and Kent
Most homeowners come to us at the same point: planning permission is either granted or not needed under permitted development, drawings are in hand, and the job now needs a contractor who can actually get in the ground. We work directly for homeowners as well as for main contractors, architects and developers, and we are equally comfortable taking a single-storey rear extension from strip-out to damp-proof course or delivering the full shell up to plate height.
Our team has decades of combined experience in groundworks, foundations and brickwork, and we work alongside structural engineers and building control inspectors throughout so that every stage is signed off as it happens rather than argued about later.
What We Do on an Extension Project
A typical extension package from us covers:
- Site set-up, protection and access arrangements, including tight or rear-garden access
- Demolition of existing outbuildings, patios, conservatory bases and old slabs
- Excavation and muck-away, including grab lorry and skip logistics
- Foundations — strip, trench fill, reinforced raft or piled caps to engineer’s design
- Drainage: new runs, connections to existing manholes, diversions and soakaways
- Substructure blockwork, cavity fill, oversite and damp-proof course
- Beam and block or insulated slab floors
- Facing brickwork and blockwork, including brick matching to your existing house
- Lintels, openings, cavity trays, weep vents and cills
- External works on completion — patios, paths, steps and retaining walls
Extension Foundations Explained
Strip and trench fill foundations
Most domestic extensions in the South East sit on either a traditional strip footing or a trench fill foundation. A strip footing is a band of concrete at the base of the trench with blockwork built up off it. Trench fill pours concrete almost to the top of the trench instead, which costs more in concrete but is far quicker and safer when the trench is deep — which is why it has become the default on many clay sites in Surrey and Sussex.
Depth, ground conditions and trees
Foundation depth is not a matter of preference. It is driven by the ground you are building on, and it is checked by building control at excavation stage under Approved Document A of the Building Regulations. On stable non-shrinkable ground a shallow footing may be acceptable, but much of Surrey, Sussex and Kent sits on shrinkable clay, where foundations commonly go down to around a metre — and considerably deeper where there are trees or hedgerows nearby, because clay moves as roots draw moisture out of it. Industry guidance such as NHBC Chapter 4.2 sets out how close a tree can be before you need to go deeper, and we work to it as standard.
This is the single most common reason an extension quote changes: the trench is opened, the inspector asks for another 300mm, and the concrete volume goes up. We would rather flag that risk with you before we start than surprise you halfway through.
Piled and engineered solutions
Where trees cannot be removed, where made ground or a high water table makes deep trenches impractical, or where an extension has to bridge an existing drain, a mini-piled foundation with a reinforced ground beam is often the sensible answer. We install to the structural engineer’s design and coordinate the sequencing so the piling rig gets access before the walls go up.
Brickwork and Brick Matching
An extension is judged from the outside, and the giveaway is always the brick. We help you source a facing brick and a mortar colour that sit comfortably against the existing elevation, and we match the bond and the pointing profile as well as the brick itself — because a modern stretcher bond in a crisp grey mortar next to a weathered Victorian wall will look wrong no matter how good the brick is.
If you want to understand the options before you decide, our guides to stretcher bond, Flemish bond and English bond explain the differences and where each is normally used.
What Affects the Cost of Extension Groundworks
We price every extension individually, because two jobs of identical floor area can differ enormously once you look at the detail. The factors that move the number most are:
- Access. Whether a machine and a lorry can get to the rear of the property, or whether everything has to be dug and barrowed by hand
- Depth and ground conditions. Clay, made ground, tree influence and water all push the trench deeper and the concrete volume up
- Spoil disposal. Volume of muck-away and whether it is classed as contaminated
- Drainage. Whether you are connecting to an existing manhole nearby or diverting a run under the new footprint
- Existing structures. Underpinning, or working alongside a neighbour’s wall under the Party Wall etc. Act 1996
- Brick specification. A standard stock brick and a hand-made or reclaimed match are not comparable
- Floor build-up. Beam and block versus an insulated ground-bearing slab
We will not quote a rate per square metre over the phone and then revise it once we are on site. We would rather visit, look at the access and the drawings, and give you a figure you can plan around.
How Long Does the Groundworks Stage Take?
For a straightforward single-storey rear extension with reasonable access, the groundworks and substructure stage is usually measured in weeks rather than months, with foundations and drainage completed before the brickwork above damp-proof course begins. Deep or piled foundations, drain diversions and poor access all extend that. We give you a programme at quotation stage and tell you which stages depend on a building control inspection, because those are the points where a day’s delay is outside anyone’s control.
Areas We Cover
We work throughout Surrey, Sussex, Kent and Greater London, including Crawley, Reigate, Redhill, Horley, Oxted, Dorking, Caterham and the surrounding villages. You can read more about our brickwork coverage in Surrey, Sussex and London.
Frequently Asked Questions
Do extension foundations need building regulations approval?
Yes. Even where an extension falls under permitted development and needs no planning permission, the structural work still has to comply with the Building Regulations. Building control will normally want to inspect the open trench before concrete is poured, and again at damp-proof course level.
How deep do extension foundations need to be?
It depends entirely on the ground. On firm, non-shrinkable soil a relatively shallow footing can be acceptable, but on the shrinkable clay found across much of Surrey, Sussex and Kent foundations commonly need to be around a metre deep, and deeper again where trees or large hedges are close by. The depth is confirmed on site by the building inspector once the trench is open.
Can you match the bricks on my existing house?
In most cases, yes. We help you source the closest available facing brick and match the mortar colour, bond pattern and pointing profile so the new elevation reads as part of the original building. Where an exact match no longer exists, reclaimed brick or a deliberate contrast detail is often a better result than a near-miss.
Do you carry out the drainage as well as the foundations?
Yes. Drainage is part of our groundworks package, including new runs, connections into existing manholes, diversions where the extension crosses an existing drain, and soakaways for surface water.
Do you work for homeowners or only for developers?
Both. We deliver groundworks-to-DPC packages for developers and main contractors, and we also work directly for homeowners on single extensions. The same team and the same standards apply either way.
Get a Quote for Your Extension
Send us your drawings and we will come and look at the site. Call 01293 225853, email info@mlscontractors.co.uk, or use our contact form and we will get back to you.