GS Renovation extends houses across Mill Hill, where the plots are generous, the ground is largely London Clay and the planning position changes street by street. Rear, side return, wrap around and double storey, all built to the structural engineer's design and inspected by Barnet Council's building control, with more than 30 years of hands on experience behind the work.
Foundations on Mill Hill's clay
Extension foundations here start with a hole, not a price. We dig trial holes to find what is actually under your garden, because the ridge does not sit on one uniform stratum and the depth your house was founded at in 1935 tells you very little about what the new work needs today. On shrinkable clay the foundation has to go below the zone that dries out seasonally, and nearby trees push it deeper again, following the engineer's design and the standard tables relating species, mature height and distance from the trench.
Where trees are close, depth on its own is not the whole answer. Clay dried out by roots will swell again if those roots are cut or the tree dies back, so the design often includes compressible board against the face of the foundation and a void former beneath any ground bearing slab, giving the clay somewhere to go instead of lifting your new floor. Where a tree is protected, or stands within the conservation area, the engineer designs around it and you notify Barnet rather than quietly taking it down.
Green Belt, conservation area and permitted development
Mill Hill's planning position is unusually varied for one postcode. Land to the north and east falls within the Green Belt, where an extension is judged on whether it is a disproportionate addition over and above the size of the original building, a test that bites well before the usual householder limits do. Mill Hill Village and The Ridgeway sit inside a conservation area, where permitted development rights are narrower and can be cut back further by an Article 4 direction. The interwar streets near the Broadway are usually the most straightforward.
So we establish the route before anything is drawn: permitted development, the larger householder extension prior approval procedure, or a full householder application to Barnet Council. The Building Regulations apply either way, covering structure, insulation, drainage and fire safety. On the excavation side, digging foundations within three metres of a neighbour's building and below their foundation level is notifiable under the Party Wall etc. Act 1996 even between two detached houses. We prepare the notice and set the timing; you serve it as building owner.
- Levels, drainage and landscaping made good around the new build
- Trial holes to set foundation depth near drains and trees
- Flat and pitched roofs with rooflights or lanterns
- Planning applications and permitted development assessments
- Foundations, groundworks and steel frames
The GS Renovation Difference in Mill Hill
Extensions in NW7 go wrong at two ends, the ground and the consent. We deal with both first, with trial holes and an engineer's foundation design at one end and an honest read of the Green Belt, conservation area and permitted development position at the other. Then one team builds it through to decoration, inspected by Barnet Council's building control at each stage as the work proceeds.
- Brick and mortar matched to the existing elevation
- Our own trades on site rather than a chain of subcontractors
- A dedicated project manager from first survey to handover
- Paperwork and certificates handed over for when you sell
- One point of contact on the phone, not a call centre
- Building control inspected at foundation, damp course and steel stages