The circle somebody scaled off a supplier PDF
It usually arrives on the plan as a single circle about the size of a small bedroom, dropped into the lobby by whoever had a manufacturer's planning sheet open that afternoon. The number it was scaled from is almost always the internal drum diameter — the swept circle of the wings, which is the smallest of the several dimensions the finished assembly actually occupies. Around it the lobby is already committed: the grid is set, the core has a position, the slab edge has been issued to the structural engineer, and the client's fit-out consultant has drawn a reception desk on a line nobody wants to move.
What makes this worth an hour of proper checking, rather than a glance, is that a revolving door cannot be quietly shaved. A swing door leaf loses fifty millimetres and nobody notices. A sliding entrance drops from a bi-part to a single slide and the opening survives. A revolving door exists only in the diameters its maker builds, the steps between those diameters are coarse, and every one of them is tied to a wing count, a throat width and a canopy that came as a set. The fit test has one of two answers, and the useful moment to get it is while the lobby wall is still a line rather than a poured element.
So the sequence below runs outward rather than inward. Start with what the door itself reserves in plan, add the clearance the installation drawing asks for around it, then place the doors the accessibility and fire documents require beside it — because those are what usually break the arrangement, not the drum — and only then hand whatever wall is left over to the storefront framing, which is the one part of the entrance that will happily take any dimension you give it.
What an entrance revolving door is made of
- Canopy and drive head — houses the bearing, the operator and the controls on an automatic unit, overhangs the enclosure it sits on, and needs a service access route nobody draws until the ceiling is coordinated
- Wing assembly and centre shaft — the rotating part, glazed in safety glass with brush seals at every edge, and the only component whose swept circle equals the number most people quote as the door size Architectural Glass Weight Calculator
- Curved drum enclosure — the fixed curved glass and its posts, standing outside the swept circle, and the element whose outside face plus a working allowance is the floor area the lobby has to give up Commercial Revolving Door Vestibule Footprint Calculator
- Storefront head and jambs — the aluminium framework the enclosure lands against, bought by the linear metre of head, sill and jamb run once the door has fixed both of its hard points Storefront Aluminum Framing Linear Footage Calculator
- Threshold ring and finished floor — the levelness under the drum is a manufacturer tolerance rather than a normal lobby floor tolerance, and the matting recess has to be set out before the screed is poured
Four diameters, and the door is only one of them
The innermost figure is the drum, or internal, diameter: the circle the wings sweep. It is the number in every product name and the one a client repeats back to you. Outside it sits the enclosure diameter, which adds the curved glass, its framing posts and the thickness of the drum wall — a real increase, and it is measured to the outside face of the finished element, not to a centre line. Above both sits the canopy, which on most units is a shallow cylinder overhanging the enclosure so that the drive, the bearing and the ceiling lighting have somewhere to live; it is the widest thing in the assembly and the last one anyone remembers to check against a soffit.
The fourth figure is the one that actually decides the fit, and it is not published as a diameter at all. It is the enclosure plus whatever working allowance the installation drawing requires around it: room to stand a curved lite, room to shim and level the base ring, room to get a hand behind the posts to make the wall junction, and on an automatic unit room to reach the drive and the sensors after handover. That allowance is not a rule of thumb and it varies with wing count, with manual against automatic operation, and from one maker to the next. Take it from the specific unit's installation drawing and treat any figure you carried over from a previous job as a placeholder.
Wing count changes the arithmetic in a way diameter alone does not. A four-wing door always has two wings in contact with the drum wall, so there is never a straight-through path and the door behaves as a continuous air lock — which is usually why it was specified. A three-wing door of the same diameter offers a noticeably wider throat, which is what a building with luggage trolleys, pushchairs or delivery traffic needs, and it gives up part of the sealing behaviour to get it. Large two-wing automatic doors trade both away for a compartment big enough to take a group, and they are physically much larger for the same throughput. None of that is a preference to settle late: it moves the diameter, and the diameter is what you are trying to fix.
The throat is the dimension the building's users experience, and it is a consequence rather than an input. It falls out of the diameter and the wing count together, and it is the reason a door that fits the plan can still be the wrong door — a drum sized to the last free metre of lobby wall may have a throat too narrow for the traffic the entrance was designed to carry. Where throughput matters, ask the maker for the capacity figure for that specific diameter and wing count rather than deriving one, because the honest answer depends on the operating speed, and on an automatic door the speed is limited by the safety standard the unit is certified to.
There is one more number that belongs on the same sheet even though it has nothing to do with normal use: the aggregate clear width the door produces when its wings are collapsed. That figure is a fire and egress input, it comes from the collapsing arrangement rather than the drum, and the section on egress below is where it is spent. Record it with the other four rather than chasing it later from a different consultant.
| Dimension | What it measures | Where the figure comes from |
|---|---|---|
| Internal drum diameter | The circle the wings sweep | Door maker's planning drawing |
| Enclosure diameter | Outside face of the curved glass and its posts | Door maker's planning drawing |
| Canopy diameter and depth | The overhang above, plus the headroom it eats | Canopy detail, checked against the ceiling |
| Reserved floor circle | Enclosure plus the installation working allowance | Installation drawing for that specific unit |
| Throat width | The clear passage a user actually walks through | Diameter and wing count together |
| Collapsed clear width | Aggregate width with the wings folded | Fire strategy, against the adopted code |
Take the enclosure diameter and the clearance from the installation drawing, not the drum diameter from the product name, and this returns the circular floor area the lobby has to surrender before anything else on the plan can be trusted.
The overall diameter of the revolving door drum/enclosure.
The extra clearance required around the door beyond its diameter.
Required vestibule footprint area
63 ft²
Clearance allowance and exact footprint shape vary by manufacturer and door configuration (3-wing vs. 4-wing, manual vs. automated) — confirm the specific unit's required footprint from its installation drawings.
They open the calculator with your figures already in it
Commercial Revolving Door Vestibule Footprint Calculator: 63.03 ft² — shown in imperial, US market. The link sets both, so the result they see is the one on your screen.
What this calculation does not cover
- Covers the drum and nothing beside it. A revolving door cannot serve as the required means of egress on its own: codes call for a conforming side-hinged swinging door in the same wall within about 3 m (10 ft), and they credit the revolving door with only a capped share of the occupant load. That swing door and its own maneuvering clearances have to fit into the vestibule alongside this circle.
- The circle is not an accessible route. Wheelchair users, strollers and anyone with a service animal use the adjacent door, which needs clear floor space on both sides and the approach clearances for its swing — planned as part of the entry rather than squeezed in after the drum is located.
- Plan area says nothing about what happens above and below it. The canopy carries the drive, the controls and the drum ceiling, so it needs a supported header and a soffit depth to hide it, and the floor takes a recessed pivot ring or threshold detail that has to be set into the slab before the finish goes down.
Nothing that revolves is on the accessible route
The 2010 ADA Standards for Accessible Design are unambiguous at Section 404.2.1: revolving doors, revolving gates and turnstiles are not permitted to be part of an accessible route. ICC A117.1, Accessible and Usable Buildings and Facilities, carries an equivalent position, and ISO 21542 treats the subject the same way for projects working to an international brief. So a compliant swinging or sliding door has to exist beside the revolving door, and it is not a concession or a secondary entrance — for a meaningful share of the people using the building it is the entrance, and siting it as an afterthought at the far end of the elevation is a design failure that will be read as one.
That door brings its own floor area, and this is where lobby schemes usually come apart. A manual swinging door needs a maneuvering clearance on both faces, sized by the direction of approach and by whether the person is pushing or pulling — the table at ADA Section 404.2.4.1 sets those depths, and they are larger on the pull side and larger again on a latch-side approach. The clear opening width is measured with the leaf open ninety degrees, not from the frame. And the floor within that maneuvering space has to be effectively level, which on the outside face means the paving fall that was drawing water away from the threshold now has a flat landing sitting in the middle of it.
Draw both clearances on the plan as hatched rectangles at the same time as the reserved circle, and draw the exterior one on the landscape drawing too. Two things routinely eat them: the reserved circle itself, when the swing door is pushed hard against the drum to keep the elevation tidy, and the reception or security line inside, which is set out by a different consultant working on a different drawing. A clearance that overlaps the swept circle of a revolving door is not a clearance, and neither is one that a speed gate stands in.
The revolving door has no swing, but the compliant door beside it does — set the approach direction and whether it is pushed or pulled, and this gives the clear depth that has to be kept free on that face before the lobby layout goes any further.
The direction someone arrives at the door from in a wheelchair.
Whether the door swings toward the person or away from them.
Whether the door has a self-closing device.
Whether the door has a latch that must be released to open it.
The clear width through the doorway with the door open ninety degrees.
Required clear depth at the door
60 in
The clear opening entered is at or above the 32 in minimum. The space alongside is measured beyond the latch side for front and latch approaches; for a hinge-side approach, check the figure in 404.2.4.1 for which jamb it is taken from before setting out. The maneuvering space must be level, within a slope of 1:48 in any direction, and must be clear of the door's own swing. Matching the figures quoted is not compliance. The rest of the requirement, and the installed work, are outside what this page can see.
- Clear space required alongside the doorway
- 18 in
- Total clear width of the maneuvering space
- 50 in
- Minimum clear opening width at the door
- 32 in
They open the calculator with your figures already in it
ADA Door Maneuvering Clearance Calculator: 60 in — shown in imperial, US market. The link sets both, so the result they see is the one on your screen.
Add the equipment this sizes
This result is a specification — 60 in — not a quantity. Put the thing it sizes into your project: how many, what you call it, and your supplier’s price.
What this calculation does not cover
- Manual swinging doors and gates only. Sliding, folding, automatic and power-assisted doors are covered by different provisions, and doorways without doors different again.
- Does not cover doors in series, recessed doors, or the additional clearance a recess deeper than 8 in (203 mm) imposes on the approach.
- Says nothing about opening force, closing speed or hardware operability, which are separate requirements a compliant landing does not satisfy on its own.
What has to stay clear at both mouths
A revolving door discharges people at two points on its circumference, and both need somewhere to arrive. Inside, that space is nearly always contested: it is where the entrance matting stops, where the desk sits, where the speed gates line up, and where the lift lobby traffic crosses. Outside, it is where the canopy drip line lands and where the paving starts to fall. The relevant accessibility check on both is the turning space — a circular clear floor area of the minimum diameter ADA Section 304.3.1 sets, unobstructed by protrusions or fixed elements, with the same requirement expressed in ICC A117.1.
Check it as an available rectangle rather than as a drawn circle, because that is what the lobby actually offers: the width between the drum and the nearest fixed thing, against the depth from the storefront line to the desk or gate line. If the shorter of those two dimensions is under the required diameter, the space fails regardless of how generous the plan looks, and the fix is almost always to move a piece of furniture that has not been ordered yet rather than to move a door that has.
Measure the width and depth of the clear floor at each mouth of the door — to the desk line, to the gate line, to the drum — and check the limiting dimension against the turning space the standard requires.
The available clear width of the floor space.
The available clear depth of the floor space.
Limiting available dimension
5 ft
MEETS the 60 in (1,524 mm) circular turning space minimum. This checks only the 60-inch (1.524m) circular turning space requirement of ADA Section 304.3.1 — it does not check the alternative T-shaped turning space option (Section 304.3.2), floor slope (max 1:48), surface requirements, or obstructions/protrusions into the space.
- Required minimum diameter (ADA 304.3.1)
- 5 ft
They open the calculator with your figures already in it
Wheelchair Turning Space Clearance Checker: 5 ft — shown in imperial, US market. The link sets both, so the result they see is the one on your screen.
What this calculation does not cover
- Two dimensions can only describe a rectangle. A bathroom that wraps around a vanity, or a landing that narrows past a radiator, has no single clear width and depth — enter the overall room and this reports a pass while no 60 in circle actually fits anywhere in the clear area. What has to fit is one continuous unobstructed circle in one location, and on an irregular plan that gets drawn, not measured twice.
- The turning circle is one geometry in the room and it has to coexist with others. Maneuvering clearance on the pull side of the door and clear floor space at each fixture are separately dimensioned areas with their own rules, and a room can hold a compliant circle while the door approach or a fixture approach has nowhere to go. They are permitted to overlap one another, which is what makes this a layout exercise rather than a sum of areas.
- 60 inches is this document's minimum, not a design target and not the only figure in play. Larger powered chairs and mobility scooters need more room to come about than the minimum circle allows, and a space held to a different standard — a dwelling unit, or a jurisdiction working from ICC A117.1 rather than the 2010 ADA Standards — is measured against that document's own dimensions instead of this one.
What the door counts for when the building empties
A revolving door is treated as a special door by the means of egress provisions, and the arithmetic is restrictive everywhere. In jurisdictions on the International Building Code the governing material sits in Chapter 10, Means of Egress, within Section 1010, Doors, Gates and Turnstiles; that section has been renumbered between editions, so read the edition your authority has actually adopted rather than a subsection number carried over from a previous project. NFPA 101, Life Safety Code, addresses the same door type where it is the adopted document. In the United Kingdom the position is set by Approved Document B, Volume 2, and by BS 9999, Code of practice for fire safety in the design, management and use of buildings.
The shape of the restriction is consistent even where the numbers are not. The code caps how much occupant load a single revolving door may be credited with, caps the proportion of the total required egress capacity that revolving doors may make up, requires a conforming swinging door within a stated distance in the same wall, and requires the wings to collapse under a defined force to give an aggregate clear width. Speed is limited too, with the limit keyed to diameter and to whether the door is manual or power driven. Each of those is a real number in a real table, and each differs by document and edition — which is exactly why this guide does not print them.
The consequence for the plan is the part that matters at concept stage. A revolving door will not, on its own, discharge a lobby. The swinging doors beside it are carrying most of the required exit width, and they are sized by the occupant load of everything that drains through this entrance, which for a tall building is a substantially larger number than the lobby itself suggests. On a large entrance that frequently means a pair of doors either side of the drum, not one door tucked against a jamb, and that is a very different elevation from the one that gets sketched.
The safety standards for the door as a machine sit alongside the fire code and are separate from it. ANSI/BHMA A156.27, Power and Manual Operated Revolving Pedestrian Doors, covers the North American requirements; BS EN 16005, Power operated pedestrian doorsets — Safety in use, covers powered doorsets in Europe and the UK, and ANSI/BHMA A156.10 governs the powered swing doors that may end up beside the drum. These decide sensor coverage, the entrapment protection zones and the stopping behaviour, and they occasionally decide geometry too, because a sensor needs an unobstructed field and a signage panel bolted to a drum post can be enough to interfere with one.
Drawing the storefront once the circle has stopped moving
The moment the reserved circle is agreed, the entrance elevation gains two hard points where the drum enclosure meets the wall line. Everything else on that elevation is now discretionary, and the storefront around it is the discretionary part. Set out from those two points outward in both directions to the next fixed thing — a column, a return, a core wall — and reconcile the remainder against the storefront module. A remainder that does not close leaves either a make-up bay or a redistribution across every vertical, and both are cheap decisions on a drawing and expensive ones after fabrication has started.
The head over an entrance deserves separate thought. Storefront framing is a floor-to-head system installed between structural elements, and it is not designed to take vertical load from the structure above it. Where the entrance sits under a slab edge, a transfer beam or a long-span lintel that will deflect, the head detail needs the deeper channel that lets the structure move without pushing that movement into the frame and the glass. This matters more at an entrance than along a shopfront run, because the drum enclosure below is a rigid cylinder that will not accommodate anything.
The interface between the two packages is the recurring commercial problem, and naming it early is worth more than detailing it well later. The door maker supplies and usually installs the drum, the wings and the canopy; the glazing contractor supplies the storefront. The joint between them belongs to whoever the contract says it belongs to, and if that is unstated it becomes a variation at the worst possible moment, because it is the last joint sealed and the first one water finds. Agree the tolerance across it too: a curved enclosure is fabricated to the door maker's tolerance and the aluminium framework to the glazing contractor's, and the difference lives in that joint.
Only then is the framework worth quantifying. The head, the sill and both jambs of every opening in the run are one continuous purchase of extrusion, and it is bought by the linear metre with an allowance for mitres, splices and cut waste. A straightforward elevation carries a modest allowance; an entrance with returns, a recessed reveal and several corners carries more, and the honest response to a complicated set-out is a larger waste percentage rather than a hopeful one.
- Fix the reserved circle on the plan first, dimensioned to the enclosure face rather than to the drum.
- Mark the two hard points where the enclosure meets the wall line, and treat them as immovable.
- Place the code-required swinging doors and hatch their maneuvering clearances on both faces.
- Measure the remaining wall in both directions to the next structural fixed point.
- Reconcile that remainder against the storefront module and decide where the make-up bay lands.
- Total the head, sill and jamb runs for every opening and add the waste allowance the set-out actually deserves.
Once the door has fixed the elevation, the aluminium is a single linear quantity: add the head, sill and jamb runs of every opening in the entrance and put a waste allowance against the number of corners and splices the set-out contains.
SettingsSettings for this calculation
Waste is set to 5% by hand. Pick a tier above to replace it, or keep your own figure.
The combined length of head, sill, and jamb framing around the storefront opening(s).
Extra material to allow for cut waste, corner miters, and splices.
Track framework needed
69.3 ft
They open the calculator with your figures already in it
Storefront Aluminum Framing Linear Footage Calculator: 69.3 ft — shown in imperial, US market. The link sets both, so the result they see is the one on your screen.
Estimated cost — your price
This site holds no price list for this material — local prices vary too much to publish honestly. Enter your supplier's price and the result is costed with it.
What this calculation does not cover
- One lumped run cannot be ordered. Head, sill and jamb are separate extrusions with separate part numbers — the sill is normally a different profile again, often over a subsill or flashing receptor, and the head may be a deeper receptor where the structure above will deflect into it. The total has to be split by position before it is priced, because the rates are not the same and the pieces are not interchangeable.
- Adding up each opening's perimeter double counts whatever two openings share. In a continuous storefront the member between two bays is one jamb, not two; at a corner the two jambs become a single corner post or a two-piece assembly; and where framing dies into a wall it is a perimeter channel rather than a jamb. Measure the openings independently and the tally comes in over.
- Entrance doors are not framed in this track. A door opening takes heavier jamb and header profiles, usually reinforced and machined for the closer, pivot or panic hardware, with a threshold below it that is a different item again — so a run containing a doorway cannot be carried at the standard framing rate this number implies.
Above the canopy and below the finish
Headroom is the constraint that kills more revolving doors at planning stage than floor area does. The enclosure height, the canopy depth and the service clearance above the canopy stack up into a dimension that has to fit beneath the lobby soffit, and on an automatic unit the canopy is not a cosmetic lid — it holds the drive, the bearing and the control gear, and every one of those has to be reachable after the ceiling is finished. Coordinate the access route at the same time as the ceiling grid, because the alternative is a maintenance visit that starts by dismantling a plasterboard bulkhead. Power and controls need a route to the canopy as well, and on a manual door a speed governor and any locking arrangement still need one.
Below, the floor is a tighter piece of work than a lobby slab normally is. The wing seals sweep the floor at a fixed radius, so any deviation in level across the drum shows up either as a gap the seal cannot close or as a wing binding on the finish. Manufacturers state a levelness requirement across the door diameter, and it is routinely tighter than the general floor tolerance a lobby slab is specified to under ACI 117, Specification for Tolerances for Concrete Construction and Materials, with the measurement itself made by the method of ASTM E1155, Standard Test Method for Determining FF Floor Flatness and FL Floor Levelness Numbers. Take the number from the door maker's drawing, put it in the concrete package as a local requirement over the entrance area, and check it before the unit is delivered rather than on the day it is being set.
Two more things are decided at slab level and cannot be recovered afterwards: the matting recess and the threshold ring. Entrance matting has to sit flush, has to start outside the door and continue inside it far enough to do any good, and its recess depth is a screed decision made months before the mat is chosen. The threshold ring or base plate that the enclosure lands on has a thickness of its own that finished floor level has to accommodate. Get either wrong and the correction is a diamond saw in a finished lobby.
Why it was specified, and what quietly cancels the reason
Most revolving doors are on the drawing for a building physics reason rather than an architectural one. A tall building has a pressure difference across its entrance driven by stack effect, and a pair of swinging doors under that pressure is hard to open, noisy, and a continuous hole in the envelope; a revolving door breaks the column of air because there is no moment at which inside and outside are directly connected. That behaviour is why the door is recognised in the entrance infiltration provisions of ANSI/ASHRAE/IES Standard 90.1, Energy Standard for Sites and Buildings Except Low-Rise Residential Buildings, and in the commercial provisions of the International Energy Conservation Code, as a way of dealing with a requirement that would otherwise be met with a built vestibule taking considerably more floor area.
The reason evaporates in use, and it evaporates through the door beside it. If the compliant swinging door is the convenient one, or is left on hold-open, or is the only route a trolley can take, then the entrance is a swing entrance with an ornament next to it, and the energy case that justified the floor area was spent on nothing. That is a planning decision more than an operational one: the revolving door should be on the natural desire line and the swinging door should be immediately beside it and obviously available, rather than the arrangement being reversed to keep an elevation symmetrical. It is the one part of this exercise that no calculation settles, and the one most visible on the day the building opens.
The fit test, before the storefront is drawn
Work outward from the swept circle to the wall line. Each item below is a dimension somebody else's drawing is holding, so record where it came from as well as what it is.
- Reserved floor circle — Enclosure outside diameter plus the working allowance from the installation drawing for that specific unit — not the drum diameter in the product name.
- Canopy diameter, depth and service access — Checked against the soffit and the ceiling grid, with a route to the drive and controls that survives the finished ceiling.
- Code-required swinging doors and their clearances — Hatched on both faces, on the landscape drawing as well as the lobby plan, and level within the tolerance the accessibility standard sets.
- Clear floor at both mouths — Width and depth to the nearest fixed element — desk line, gate line, drum face — with the limiting dimension recorded rather than the generous one.
- Collapsed clear width and egress credit — Taken from the adopted code edition and the fire strategy, not from a previous project's schedule.
- Storefront head, sill and jamb run — Measured from the two hard points where the enclosure meets the wall, with the make-up bay placed deliberately.
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