Structural Steel in a London Period Property: What Opening Up Involves

Removing an internal wall — to connect a kitchen to a dining room, to open a living space across the full width of a house, or to create a single kitchen-dining-living floor — is one of the most frequently requested renovation interventions in London period properties. It creates genuine spatial value when done correctly, and structural problems when done incorrectly.

Here is what the structural engineering and construction work actually involves.

What the wall is doing

Before any wall can be removed, it is necessary to understand what structural role it is performing. Internal walls in a Victorian or Edwardian London townhouse can be:

Non-loadbearing partitions: Walls that divide space but carry no structural load beyond their own weight. These can be removed without replacement, although the floor or ceiling above may need minor patching. In period properties, these are typically the thinner walls (100mm stud or single-skin blockwork) added during subdivisions and conversions.

Loadbearing walls: Walls that support floor or roof loads from above. These cannot simply be removed — they must be replaced with a structural element (typically a steel beam) that transfers the loads they were carrying to supports at either end (typically columns, padstones on existing walls, or new foundations).

Party walls: Walls shared with an adjoining property. These are loadbearing and legally governed by the Party Wall etc. Act 1996. Any works to a party wall — including inserting beams that bear on the party wall — require a party wall agreement (see our guide to the Party Wall Act).

A structural engineer must assess the wall before any removal to confirm its status and, where loadbearing, to design the replacement beam and support structure.

The structural engineering process

Initial assessment: A structural engineer visits the property, inspects the wall, reviews the structure above it (floor joists, roof structure), and assesses the loading that the wall is carrying. For a typical Victorian terraced house, this is a straightforward assessment.

Beam design: The engineer calculates the minimum beam size required to span the opening and carry the loads above. The beam is typically a universal steel beam (I-beam) — the depth and weight of the beam depend on the span and the loads. A 3m opening might need a 178x102mm UB; a 6m opening in a four-storey house might need a 305x165mm UB or heavier.

Support design: The beam must be supported at each end. In a typical party wall situation, the beam bears on a padstone — a block of dense concrete or engineering brick — built into the party wall. In an internal situation, the beam may bear on columns (either steel or masonry piers), on existing structural walls, or on new foundations. The structural engineer designs the support system.

Temporary works: Before the permanent beam is installed, the wall being removed must be temporarily supported — typically by steel or timber props carrying a temporary beam that distributes loads while the permanent structure is constructed. The temporary works design is part of the structural package.

Construction sequence

Structural steel installation in a period property follows a specific sequence:

1. 1.Temporary propping of all loads currently carried by the wall. This typically means propping the floor above from both sides.

1. 2.Creating bearing pockets in the walls at each end of the proposed opening. These are holes cut into the supporting masonry to receive the padstones and beam ends. This requires careful cutting to avoid unnecessary disturbance to the masonry.

1. 3.Installing padstones — dense concrete or engineering brick blocks that distribute the concentrated load from the beam end into the masonry.

1. 4.Lifting the beam into position. Depending on the beam weight and the access available, this is done by hand, with a chain block, or with a small crane. A 6m steel beam weighs 100–150kg or more; this requires planning.

1. 5.Fire protection. Steel beams in domestic situations must typically be fire protected to achieve 30 or 60 minutes' fire resistance. Options: encasing in plasterboard (the most common method — the beam is boxed in and disappears), intumescent paint (a specialist coating that expands in fire to protect the steel), or leaving the beam exposed and designing the enclosure to achieve fire resistance.

1. 6.Removing temporary propping once the beam is correctly seated and bearing adequately.

1. 7.Making good — masonry patching around the padstones, reinstating floor or ceiling finishes, decoration.

The exposed beam aesthetic

Many clients want to expose the steel beam as an architectural feature — a visible I-beam at ceiling level in an open-plan kitchen-living space. This is achievable and can look excellent when properly done. The considerations:

Fire protection: An exposed steel beam in a residential space must still be fire protected. Intumescent paint is the standard solution — applied in the correct film build, it is invisible (or nearly so) on a steel beam and provides the required fire resistance. The beam should be shot-blasted and primed before intumescent application, then finished in the required colour (typically grey primer or black).

Surface quality: A structural steel beam from a fabricator will have a mill scale surface, weld marks, and surface rust. For an exposed installation, the beam should be specified to be blast-cleaned, welded to a higher standard, and finished to the required quality before delivery.

Proportions: A beam that is structurally correct for the span may be too deep for the ceiling height of the room. In these situations, the structural engineer can sometimes justify a lighter section with additional design attention, or the client must accept the depth of the beam as part of the aesthetic.

Party wall implications

Any beam that bears on a party wall requires a party wall agreement under the Party Wall etc. Act 1996. This means serving notice on the adjoining owner and appointing party wall surveyors if the adjoining owner does not consent in writing.

The party wall surveyor will prepare an Award (a formal document) that sets out the works to be carried out, the condition of the adjoining property before works begin, and the obligations of both parties. This is a legal requirement, not a formality, and there are penalties for carrying out notifiable works without serving notice.

See our separate guide to the Party Wall Act for the full process.

Building Regulations

The removal of a loadbearing wall and installation of a structural beam requires Building Regulations approval. A structural calculations package (from the structural engineer) must be submitted to the local authority's Building Control or to an Approved Inspector. A Building Control officer will inspect the beam installation during construction.

The completion certificate issued by Building Control is a legal document that confirms the works comply with Building Regulations. Without it, the works are unverified and will be questioned on any future sale of the property.

Cost benchmarks

These ranges include structural engineer fees, temporary works, beam supply and installation, fire protection, making good, and Building Regulations. They exclude decoration.

ASAAN's approach

ASAAN manages structural alteration works across London renovation projects. We commission structural engineering from qualified structural engineers, manage the temporary works programme, and carry out the beam installation and making good as part of the main construction contract.

If you are planning an open-plan renovation that involves structural wall removal, contact us to discuss scope and feasibility for your specific property.