Structural calculations in Brent

Building control charges in Brent

Brent publishes its building control fees each year. The schedule for loft conversions, single-storey extensions and multi-storey or basement extensions is in the data table on this page, taken from the council's fees and charges document. Some figures are marked as proposed for the coming year, so we confirm the current schedule before quoting your total.

Those fees go to the council. Our fee for the calculations is separate, from £295.

Basements in Brent: what planning does and does not check

Brent has a dedicated Basement Supplementary Planning Document. Its position on structure is that planning does not assess the stability of basement works, which is left to the Building Regulations and the Party Wall Act: no structural statement at validation. A basement design is therefore checked at building control, and the calculations carry the weight.

At planning, a basement impact assessment is still required: all basement householder applications. The SPD also sets limits on scale, covering depth below ground and how far into the garden a basement may reach: 1 storey; 3 m from rear; 4 m detached / 3 m other.

Front lightwells are limited too, with these figures: 3 m; 800 mm lightwell; 50% front soft landscaping. And where the site sits in a flood zone, the council asks for this: FRA + drainage strategy FZ2/3. We set these limits out at the start of a basement job, because they fix the excavation the engineer designs for.

The ground and the neighbours

The basement SPD describes Brent's geology as predominantly London Clay over a chalk aquifer. The clay acts as a barrier to infiltration and rising groundwater, so local flooding is usually surface water rather than groundwater.

Because planning leaves structure to the Party Wall Act, neighbours must be given notice. The national rule is: Adjacent excavation notice at least 1 month before work: within 3 m and deeper than the neighbour's foundations, or within 6 m and cutting a 45° line from their foundations. Our party wall notices service prepares them.

Brent homes and constraints

Only 43.3 per cent of Brent households live in a house, and 38.4 per cent own their home. The borough has 23 conservation areas, 39 Article 4 directions and 93 listed building entries. Any of them can limit structural change to the outside of a building.

Brent also records 1,229 tree preservation orders. Trees close to a new foundation or a basement affect its depth and form, and we ask about them at the first call.

Simple rules, calculation and price

Approved Document A: Structure, 2004 edition incorporating 2004, 2010 and 2013 amendments gives simple rules for common cases, and a floor supported by a wall can use them up to 6 metres between bearings. Anything beyond that, and a new beam, usually needs calculation, and the design must be done by a competent person: Design work must be done by a competent person.

The fee is £295 with VAT included, fixed after the constraints check. You receive the calculations, a beam and padstone schedule and a layout drawing, checked by a second chartered technologist. Our building regulations drawings in Brent and construction drawings in Brent use them directly.

For the borough overview, see architectural drawings in Brent. The same service is available in neighbouring Ealing, Harrow and Camden, with the national picture in the structural calculations guide.