RSJ and Steel Beam Installation Deptford

GS Renovation installs steel beams and RSJs across Deptford, from post-war flats and the SE8 warehouse conversions near the creek to the Georgian and Regency townhouses off the high street. We remove load-bearing walls safely, and on the few listed houses we work within the listed building consent.

In Deptford, a steel beam for one opening typically costs £1,500 to £4,000 fitted and signed off, or £2,500 to £6,500 or more for a full knock-through with the engineer's fee and making good (indicative London ranges, MyBuilder and Checkatrade, 2026). GS Renovation Ltd, a building contractor based in Potters Bar, does the work in Deptford.

How the job runs

1. Free site survey at your Deptford address and an itemised quote.
2. The engineer we appoint sizes the beam, and the work is registered with Lewisham Council building control or an approved inspector. On a shared wall you serve the party wall notice as building owner; we supply the drawings.
3. Props go in, the opening is cut and the beam is set on padstones, packed tight above.
4. Building control inspects the steel before it is covered. We make good, and the completion certificate follows.

Removing load-bearing walls in Deptford

In Deptford's older houses, the Georgian and Regency properties and the later terraces, the internal dividing walls are solid brick and carry real load. Before any wall comes out, the structural engineer we appoint calculates the beam size and specifies the padstones the RSJ will bear onto. We set up temporary propping, then carry out a staged, controlled demolition so the structure is never left unsupported. This measured approach matters in older SE8 houses where the masonry has settled over two centuries.

Some of these townhouses are listed and some streets sit within a Lewisham conservation area, so we treat original features with care, saving cornicing, joinery and fireplaces where the works allow. Every beam installation is notified to building control and signed off on completion, giving you the certificate you will need when you sell. Where the wall is shared with a neighbour, the Party Wall Act applies: you serve the notice as building owner (or your surveyor does), and we give you the drawings and programme it needs.

Housing in Deptford

Deptford has about 14,290 homes on the Council Tax list: 9% pre-1919, 4% interwar and 84% post-war, with flats making up 85% and houses 15%. Most homes here are flats, and a beam in a leasehold flat in Deptford needs the freeholder's licence for alterations, since the lease usually keeps the structure with the freeholder.

Steel over a new outside opening in a Deptford flat

Not every RSJ in Deptford replaces an internal wall. Some carry the brickwork over a widened opening in an outside wall, where a window becomes a pair of glazed doors onto a garden or a balcony. Lewisham's building control fees chart lists structural support for new glazing, such as a new door, as an item of its own, so the steel over that opening is notifiable work even when nothing else in the home changes. The structural engineer we appoint sizes the beam and the padstones under each end, and the inspector sees those bearings before the reveals are plastered and the new frame is sealed in.

The outside face of that wall raises a second question. Lewisham says flats or subdivided houses in conservation areas do not have permitted development rights and must seek planning permission for changes to the exterior. With flats making up 85% of Deptford's homes, and conservation areas covering Deptford High Street, St Paul's Church and Creekside, a new door opening in a flat inside one of them needs planning permission before any steel is ordered. Check the address against Lewisham's conservation area maps first. If permission is needed, the beam design waits for the approved elevation, because a wider or narrower opening after approval means a fresh calculation and a different section.

Party wall steel beams in SE8

In Deptford's tightly packed terraces and townhouses, the wall you want to open is frequently a party wall shared with the house next door. Under the Party Wall Act you must serve formal notice on the adjoining owner before cutting a bearing into that wall or inserting a beam. You serve that notice as building owner (or your surveyor does). We allow for the statutory notice period in the programme, give the surveyors the engineer's details and build to any award, so the project keeps moving.

The steelwork itself is only as good as its bearings. We form solid padstones at each end, usually in concrete or engineering brick, so the RSJ transfers its load cleanly into the existing masonry. On larger openings across a double reception or a kitchen knock-through, the engineer may specify a heavier universal beam or twin sections bolted together. We prop, install and case in the steel to the engineer's sizing, then leave it ready for plastering.

Where the beam sits and what it costs you

In a conversion or a lower-ground room, head height is the scarce commodity, and where the beam sits decides how much of it you keep. A downstand beam under the existing joists is the simplest and cheapest to build, but it drops the opening by the depth of the section plus its fire protection. In a room already tight under a Georgian first floor, that can be the difference between a comfortable space and a low one.

The alternatives are a shallower, heavier section, which keeps the drop down but costs more in steel, or setting the beam up between the joists with hangers so the ceiling runs through unbroken. The engineer will tell you which of those the structure allows. We measure the existing height, mark the proposed soffit on the wall in tape so you can see it, and agree the option before the steel is ordered, since a change afterwards means a new beam.

• Steel delivered cut, drilled and primed to the engineer's schedule
• Building control applications and inspection sign-off
• Lintel and catnic support to smaller openings

VOA Council Tax stock of properties, March 2025, for Deptford North, Silwood & Pepys and New Cross & Deptford South. Counts rounded by the VOA.

Once you know the scope of the RSJ and steel beam installation in Deptford, it helps to read home renovation in Deptford, RSJ and steel beam installation across Lewisham, London builders who fit steel, the Party Wall Act when a beam bears on a shared wall, RSJ and steel beam installation across London and Lintel Replacement Cost.

Why Deptford Homeowners Choose GS Renovation

Deptford homeowners choose GS Renovation because we understand the quirks of Deptford's concrete-framed blocks as well as its solid-wall Georgian and listed houses, and we manage the whole process from engineer's calculations to building control sign-off. One team handles the propping, the steel and the padstones, built to any party wall award, working cleanly in an occupied home and backed by our founder's 30+ years on the tools.

Checked by Abdelaaziz Saaid, founder and director of GS Renovation Ltd (Companies House no. 14611254). Structural design is by the consulting engineer appointed to your project.