Structural engineering in Lewisham

Two kinds of Lewisham house, two kinds of structure

About 42.2 per cent of Lewisham households live in a house or bungalow, and 41.9 per cent own their home. That shows in the work: lofts, rear extensions and garage conversions are common, not only flat refits.

Victorian terraces, as in Brockley and Lewisham Park, have solid brick walls, timber floors and a cut roof. A rear opening needs a beam that bears on a padstone in an old wall, and the chimney stack above must be held. Interwar semis in Catford and Grove Park are lighter. Their cavity walls and thin ground slabs suit a side or rear extension, but a loft needs the roof strengthened with steel because the original timbers were sized for tiles alone.

Approved Document A limits floor spans onto simplified-rule walls to 6 metres. Beyond that, or where the work uses steel, a removed wall or underpinning, the guidance says calculations are needed: Where the work falls outside the AD A Section 2 tables, or uses beams, steelwork, underpinning or removed load-bearing walls and chimney breasts.

Heritage, Article 4 and the shape of the borough

Lewisham has 30 conservation areas, 367 listed buildings and 57 Article 4 directions that cover 89 mapped areas. Its heritage list shows 21 assets at risk, and the borough contains 1 world heritage site within its boundary. Roofs and front elevations in the Article 4 areas are the places where structure and appearance meet.

If you live in one of those streets, a loft needs a clear view of what the direction restricts before the steel is sized, because the roof shape you can build decides the ridge beam and the floor loading. Our loft conversion drawings in Lewisham carry that planning check, and the structural design follows what they allow.

Our house extension drawings in Lewisham deal with the rear and side additions that make up most of the other work.

Garage conversions in the interwar suburbs raise one more structural point. The garage door opening has to be closed with a wall that can carry the lintel's load, and the footing under the new wall must be deep enough to avoid movement against the old slab. We draw the infill wall, the new foundation and the floor build-up on one sheet, so the builder is not left to work them out on site.

Decisions, timing and building control

Lewisham decided 578 householder applications in its latest year, granted 89.4 per cent and decided 95.2 per cent in time. Planning is quick enough that the structural design is often the pacing item, so we start it as soon as the layout is settled.

Full plans for building control are decided within 5 weeks. Where a shared wall is involved, a neighbour who does not appoint a surveyor within 10 days of a request lets the other owner appoint one, so serving notices early keeps the programme moving. A structural drawing attached to the notice gives the surveyors something definite to assess, and it shortens the exchange that follows. Our building regulations drawings in Lewisham put the engineer's work into the submission.

Quote and next step

Send the address, photographs of the walls and roof, and any drawings you hold. We check heritage status and neighbours, then quote a fixed fee. For a single beam, see structural calculations in Lewisham, and for the borough as a whole read architectural drawings in Lewisham.