Origami House: Creating a Column-Free Corner in a Victorian Extension

When we first shared Origami House, we wrote about folded ceilings, rooflights and a fabric-first retrofit. This article is about what sits behind them: the steelwork.

The project, a Victorian terrace on Dickenson Road in Haringey, North London, is now on site with its steel frame installed. With the rear walls opened up, the structural idea behind the design is visible for the first time.

Inside the model: the frame beneath the outrigger which spans to both the front and back carries its load to set-back columns, leaving the corner open.

The Problem With the Corner

At the back of the house sits the outrigger, the narrow rear wing typical of Victorian terraces. At Origami House, its ground floor walls help support the retained outrigger above.

Opening up the ground floor means those loads need a new route to the foundations. The most direct answer would be a steel column under the outrigger's outer corner.

That corner is also where the kitchen, dining space and garden meet. A column there would split the view, interrupt the glazing and fix the furniture layout around a post. Our aim was a column-free corner, so the kitchen and dining space could open towards the garden without interruption.

On site: the new steel frame beneath the retained outrigger, with the outer corner clear of any column.

The Structural Strategy in Three Parts

The structural scheme, designed by Triple M engineers, uses three groups of steelwork. Each has a distinct role.

1. A steel frame beneath the outrigger

A rectangular frame of steel beams sits beneath the retained outrigger and collects the load from the walls above. Rather than bringing that load down at the corner, the frame carries it to columns set back from it: one close to the party wall and one within the line of the kitchen.

This is what creates the column-free corner. The supports still exist; they have simply moved to where they do not interrupt the room or the view.

2. Goalpost frames to the garden

Across the extension, steel goalpost frames (two columns joined by a beam) form the openings to the garden. They define the edges of the large glazed areas. How each frame contributes to the overall stability of the extension is part of Triple M's structural design.

3. Folded roof steels

Above, raking steel beams meet to form the folded roof. Their lines follow the ridges and valleys that came from our daylight studies and the planning envelope. This is where the origami idea becomes literal: the steel traces the folds the architecture needs.

Together, the three parts turn a cellular ground floor into a single kitchen and dining space, with the retained outrigger above and an open corner towards the garden.

The folded ceilings in use: a family room for play and pause, lit from above through the rooflight.

Working With Triple M Engineers

Triple M's central contribution was a structural scheme that removes the column from beneath the outrigger's corner, carrying its load to supports positioned away from the view. That single decision shapes the whole ground floor.

Our role was to set out where openness mattered most, then coordinate the steelwork with the existing building and the folded roof geometry in our 3D model. The CGIs show this in X-ray view, with the steel in red. The model is an architectural coordination tool. The structural analysis and the sizing of each element are Triple M's.

The Steelwork on Site

The construction sequence at Origami House follows the engineer's temporary works design and the contractor's method. The planned sequence is:

1. Temporary support to the outrigger while its ground floor walls are opened up
2. New foundations to take the loads from the relocated columns
3. Steel installation: the frame, columns and goalposts lifted in, connected and packed to the brickwork above
4. Removal of temporary support once the engineer confirms the steelwork is complete
5. Roof steels installed to set the geometry of the folded roof
6. Ground slab cast over a damp-proof membrane

The site photograph shows the new steel frame beneath the retained outrigger, with the slab cast and the outer corner clear of any column.

Steel and Environmental Performance

Origami House is a fabric-first retrofit, with an air source heat pump and solar PV proposed, and AECB CarbonLite principles informing the design decisions. Structure and energy are part of the same conversation.

Thermal bridging

Steel conducts heat far more readily than masonry or timber. Wherever a beam crosses from the warm interior to the cold exterior, it can create a thermal bridge: a cold spot that wastes energy and risks condensation.

The design aims to manage this by:

• keeping steelwork inside the insulated envelope wherever possible
• using thermal breaks where structure has to cross the insulation line
• detailing airtightness membranes and tapes around steel connections

These junctions are being developed as part of the detailed design, alongside the structural information.

Embodied carbon

Steel also carries significant embodied carbon. A column-free corner needs more steel than a conventional post, and that is a real cost we weigh openly. It sits alongside the project's wider aim: retaining and upgrading the existing Victorian house rather than replacing it.

What the Column-Free Corner Gives the Home

The result is a kitchen and dining space with an uninterrupted view to the garden. Glazing can turn the corner without a post in the way, and the furniture layout can follow how the family lives rather than where the structure lands.

For anyone planning a similar Victorian house extension, three lessons stand out:

• Involve the structural engineer at concept stage, when the position of supports can still shape the design
• Decide where openness matters most before the structure is fixed, then ask the engineer to keep that area clear
• Allow for the knock-on effects: relocating supports can mean deeper steel sections, which affect ceiling heights, detailing and budget

The proposed extension at dusk: a folded portal to the garden and a glazed, column-free corner.

Frequently Asked Questions

What is a Victorian outrigger?

An outrigger is the narrow rear wing found on many Victorian terraces, often originally housing a scullery or kitchen. It typically leaves a side return alongside it, which many extensions now infill.

Can the corner column always be removed?

Not always. It depends on the existing structure, the loads involved, the foundations and the space available for steelwork. A structural engineer can advise whether it is feasible for a particular house.

Will removing the column affect ceiling heights?

It can. Carrying load over a longer span may need deeper beams, so it is worth coordinating ceiling heights and rooflight positions with the structure early in the design.

Thinking About a Victorian House Extension?

At RISE Design Studio, we believe the most sustainable buildings are the ones already standing. If you are considering a Victorian house extension, retrofit or low-energy renovation in London, we would love to explore how structure, space and performance can come together on your project.

→ Email us at architects@risedesignstudio.co.uk
→ Or call the studio on 020 3947 5886

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