Most people picture a commercial architect designing office towers, and that is a small slice of the actual work. A commercial architect spends far more time on fit outs, change of use conversions and hospitality projects than on landmark new builds, and each of those is a distinct discipline with its own rules.

Here is what the role actually covers, sector by sector, and where the real complexity sits.

Retail and Restaurant Fit Outs

A fit out is the work that turns a bare or previously occupied commercial unit into a functioning business. It is the bread and butter of commercial practice, and it is more involved than it looks.

The architect handles the spatial layout, but the harder work is compliance. Commercial premises carry requirements domestic projects never touch: accessibility under the Building Regulations, fire strategy for a space the public enters, ventilation and extraction for food premises, and often acoustic separation from neighbours above or beside.

A restaurant fit out is the clearest example. Kitchen extraction alone can drive the whole scheme, because routing a commercial flue up through a building affects everything around it, and neighbours and the council both take an interest.

Speed matters here in a way it does not on a house. Commercial tenants are usually paying rent from the day they get the keys, so the fit out programme has a direct cost attached to every week. A commercial architect designs with that clock running.

Change of Use

This is where a commercial architect earns their keep, and where the rules changed significantly in recent years.

The Use Class E framework, introduced in 2020, grouped shops, offices, restaurants, gyms and various other uses into a single class. Within Class E, a building can often switch from one use to another without a planning application at all, because it is not technically a change of use in planning terms.

That flexibility is powerful. A former shop can become a restaurant, an office can become a gym, frequently without the full planning process, provided the building can physically and legally support the new use.

The word “physically” is where the architect comes in. A commercial floorplate rarely translates neatly into a different use. The architect assesses whether the building actually suits the new purpose, considering structure, light, access, drainage, ventilation and Building Regulations compliance, then designs the conversion to work.

Extension Architecture handled exactly this kind of project in Kingston, converting a former butcher’s shop, an A1 retail unit under the old system, into a restaurant use. That conversion is a good illustration of the point: the planning position was navigable, but the practical work of making a retail space function as a commercial kitchen and dining room, with all the extraction, drainage and fire compliance that involves, is the actual job.

Not every change is permitted development, and some routes still need prior approval or a full application, particularly conversions to residential. Establishing which route applies is the first task, before any design.

Office and Workspace

Office work has shifted since the return to the workplace, and commercial architects in London have seen a genuine uptick in high end workspace projects as employers compete to bring people back.

The work here is about reconfiguring space for how people actually work now: a mix of collaborative areas, quiet zones, meeting space and amenity, rather than rows of identical desks. It also increasingly involves upgrading older buildings to modern energy performance standards, because tenants and regulations both now demand it.

The compliance backdrop is heavier than it used to be, particularly on larger buildings, following the Building Safety Act and its dutyholder regime. That has made clear accountability for design and fire safety a central part of commercial work rather than an afterthought.

Hospitality and Hotels

Hotels are their own discipline, and interestingly, a growing one. With residential planning slow and uncertain, developers have increasingly turned to hotels, which can be quicker to get moving and to generate returns.

Hotel design combines almost every commercial challenge in one building. Guest rooms need acoustic separation and consistent servicing. Public areas, restaurants and bars need to handle flow and fire strategy for large numbers of people. Back of house, kitchens, laundry, plant and staff areas has to function invisibly. And the whole thing has to deliver a guest experience that justifies the room rate.

It is a sector where the architect coordinates an unusually wide range of specialists, from structural and services engineers to acoustic and fire consultants, and where the operational brief from the hotel operator shapes the design as much as the site does. A practice offering hotel architects works to that operator brief from the first sketch, because a hotel that does not work operationally does not work at all.

The Thread Running Through All of It

Across every commercial sector, the same distinction separates commercial work from residential.

Domestic projects are judged mostly on planning and amenity. Commercial projects carry a much heavier compliance load: public access, fire strategy for numbers of people, accessibility, ventilation, acoustic performance and, increasingly, energy standards. The design has to satisfy all of that while still delivering a space that works commercially and can be built to a programme that respects the rent clock.

The other constant is that time is money in a way it rarely is on a house. A commercial client is usually losing money for every week a unit sits unable to trade, so a commercial architect designs with the programme as a live constraint, not a nice to have.

What to Look For in a Commercial Architect

Three things separate a practice that can genuinely handle commercial work from one that mostly does houses.

Relevant sector experience. A restaurant fit out, a Class E conversion and a hotel are different disciplines, and experience in one does not automatically transfer to another.

A grasp of the current compliance regime, particularly the Building Safety Act dutyholder requirements on larger buildings, because getting accountability wrong there is a serious problem.

And an understanding of the commercial clock. A commercial architect who does not design around the rent and the trading date is missing the constraint that matters most to the client.

The role is broader than the office tower cliché suggests. Most of the value sits in the unglamorous work: making a difficult space compliant, a change of use viable, and a programme deliverable while the client’s costs are running.