Structural calculations in Bromley

Ground and groundwater in the borough

Bromley's flood risk assessment describes permeable Thanet Sands in the north and Chalk in the south, and records that most groundwater flooding incidents occurred on those formations. For any basement or lowered floor it advises detailed ground investigation, particularly basement development.

For a house that is only gaining a beam, the ground matters less, but new foundations for a rear extension still depend on what is beneath the garden. We ask what the builder or neighbours already know about soil and water in your street and flag any case where a trial pit is worth paying for before the foundation is sized.

Houses, extensions and the beams they need

Bromley is a borough of houses: 68.6 per cent of its 135,827 households live in a house or bungalow, and 68.5 per cent own their home. That mix produces a steady run of rear extensions, loft rooms and open-plan kitchens, each needing a steel beam over a wide opening or a new floor structure.

Where a house is semi-detached or terraced, the beam can bear on a party wall at one end. We check the bearing on each end and record the padstone, so the builder does not improvise at the wall.

Before any figure is calculated we survey the existing walls. We note whether each one is solid brick or cavity, how thick it is and what sits above and below the opening, because the loads reaching each bearing depend on those details. A calculation that starts from assumptions about the house next door is only as good as the guess.

Typical requests include a ground-floor opening between kitchen and dining room, and a dormer or rear loft where the old ceiling joists cannot become a floor.

Conservation areas, Green Belt and listed buildings

Bromley has 47 conservation areas and 108 Article 4 directions, and 51 per cent of the borough is covered by Green Belt. These do not change how a beam is calculated, but they can change what is built and what the council needs to see with a planning application.

The council's validation guidance asks for a structural survey and rebuilding method statement where a listed or locally listed building is to be demolished, or where a Green Belt building is converted. If your house falls into either group, tell us at the start so the structural work is scoped for planning as well as for building control.

What you receive and what it costs

In Bromley the fee begins at £295, VAT included, and is fixed once we have checked the constraints on your address. You receive the calculations, a beam and padstone schedule and a layout drawing, normally about a week after the survey. A technologist who did not draft the set checks it before it goes to the council, and if the examiner asks for changes we revise at no charge.

Bigger structures are priced on the same basis. Tell us early if the job includes a chimney breast removal, a new foundation or a wall that carries a floor above, since each adds elements to check and we would rather price them at the start than discover them on site.

The package sits alongside our building regulations drawings in Bromley, and the same figures feed the planning drawings in Bromley where an application is needed.

Where else to look

The full service is explained on our structural calculations page, and the borough picture is at architectural drawings in Bromley. Working on a house near the Croydon boundary? See structural calculations in Croydon, where the council asks for different paperwork.