Whether you're taking a first floor on Richmond Hill or rethinking a tired unit on Aviation Park, the same question comes up before anything else: how many people will actually fit? The honest answer is that the legal minimum and the workable figure are miles apart, and knowing both stops you signing a lease you'll regret.
The Workplace (Health, Safety and Welfare) Regulations 1992 set the floor at 11 cubic metres per person. With a standard 2.4m ceiling that works out at roughly 4.6 square metres of floor area, and any ceiling height above 3m is ignored in the calculation. Space taken up by furniture, storage and partitions doesn't count towards it either.
Treat that as a compliance backstop rather than a target. An office planned at 4.6 sq m per head feels cramped, gets noisy fast and tends to breach fire escape and desk spacing guidance long before anyone complains about the square metreage.
Those headline figures cover far more than a desk. A 1400mm x 800mm desk with a chair and a 700mm pull-out zone occupies around 2.5 to 3 sq m. Circulation, the walkways and gangways that let people move without squeezing past chairs, typically eats another 25 to 40 per cent of the floorplate.
Then come the shared areas. A four-person meeting room needs roughly 9 to 12 sq m, a six to eight person room 16 to 20 sq m, and a decent tea point with a sink, fridge and a bit of standing room rarely works below 8 sq m. Two acoustic booths for calls will take another 3 sq m or so. Add WCs, a comms cupboard and a coat and storage run and you can see where the difference between 4.6 and 10 sq m goes.
Most Dorset businesses we speak to no longer plan one desk per employee. A desk sharing ratio of 0.6 to 0.8 desks per head is common where people are in three or four days a week, which means 30 staff might need 18 to 24 desks rather than 30.
The catch is that the space you free up rarely stays empty. Hybrid teams need more meeting rooms, more call booths and better video kit, because the days people do come in are the collaborative ones. Plan on reinvesting most of the saved floor area rather than banking it, and be realistic about your busiest day rather than your average.
Advertised floor areas are usually gross internal or net internal, and neither is what you can plan on. Once you deduct the core, structural columns, riser cupboards and the lobby, the truly usable area in an older Lansdowne or Old Christchurch Road conversion can be 10 to 20 per cent below the headline figure. Period buildings with deep bay windows and awkward returns lose more again.
Ceiling height matters too, both for the cubic metre calculation and for what you can do with lighting and acoustics. Anything under about 2.6m makes suspended acoustic rafts and high partitions difficult. Before you commit, walk the space with a tape measure and a rough furniture layout, and check where the existing power and data floor boxes sit. Moving small power in a fitted-out office is one of the more avoidable costs, and it's easier to plan desk runs around what's there than to rewire the floor.
A quick way to test a space: take the net usable area, subtract your meeting rooms, tea point and storage, then divide what's left by the number of desks you need. If the answer drops below about 6 sq m per desk, something has to give.
Test layouts cost far less than a bad lease. A simple space plan drawn over the landlord's floor plan will tell you within a day or two whether 40 people fit properly or whether you're really looking at 32.
Yes, 11 cubic metres per person is the minimum under the 1992 Workplace Regulations, which is about 4.6 sq m at a 2.4m ceiling height. It is a legal floor, not a sensible design target, and most offices planned that tightly feel unpleasant to work in.
Around 1,000 sq ft is roughly 93 sq m, so at a comfortable 10 sq m per person that's about nine people including a small meeting room and tea point. Push it to eight sq m per head and you might get eleven or twelve, but circulation and storage start to suffer.
Yes, the 9 to 12 sq m benchmark is meant to cover the whole floorplate including meeting rooms, breakout, circulation and storage. If you only count desk space you'll consistently underestimate how much building you need by a third or more.