Typical split: three down, two middle, one on top.
The top floor: one machine at most, two drops, and a terrace or roof door you can open for twenty minutes when it gets crowded.
2. Treat the middle floor as a pass-through. It receives from below and exports upward at the same time, so it holds fragrance poorly in circulation areas and well only behind closed bedroom doors. Put its machines inside rooms, never on the landing.
3. Give the top floor one machine at most. Often none. It is the terminus of the rising column and already receives a composite of both floors below. Two drops rather than four if you do run something.
4. Use a roof or terrace door as a vent. A three-floor house with roof access has a relief valve most homes do not. Twenty minutes with that door open clears an over-loaded top floor faster than any change of machine or fragrance.
5. Both stairwells stay empty. Two staircases means two moving columns of air. Neither takes a machine, and both landings are already scented by the floor beneath them.
Made in India, composed by an ISIPCA Versailles-trained perfumer — and a portion of every order supports girl-child education through Nanhi Kali.
Why the top floor is the hardest floor to keep neutral
The stack effect does not simply repeat on each storey — it compounds. Warm air rises through the stairwell from the ground floor and arrives at the first-floor landing carrying whatever the living room is producing. It does not stop there: it keeps rising, and on its way through the middle floor it picks up whatever that floor is producing too. By the time it reaches the top, the column is carrying a composite of two floors. The top floor of a triplex receives more scent, from more sources, than any other part of the house, and it has nowhere to pass it on to. A duplex upper floor is in mild surplus. A triplex top floor is in permanent, cumulative surplus.
Which changes the whole logic of what you do about it. In every other part of a house, a room that smells wrong is a room that needs a machine, a different fragrance or a better position. On a top floor the same complaint almost always means the opposite: too much is arriving from below. The corrections are subtractive — take a drop or two out of the ground-floor tanks, move a ground-floor machine further from the stair foot, run the lower floors earlier and for less time, and open a terrace or roof door for twenty minutes to vent the column entirely. Adding a machine to a top floor is treating an overflow by turning on another tap.
The three decisions in a three-floor house
SOSA Sukoon₹1,899Three Sukoons at ₹5,697 is the usual answer: two at opposite ends of the open living-dining and one in whatever ground-floor room has a door. The deficit here is larger than in a duplex because the column above is taller and pulls harder, so this floor genuinely runs at the top of the dose range — three to four drops per tank. Keep every machine as far from the foot of the staircase as the furniture allows. If the ground floor is one very large open double-height volume above roughly 2,000 sq ft, the waterless Vaayu at ₹11,999 is the machine for that shape — it nebulises neat oil and cannot use the water-based Hotel Collection.Floor by floor, all three
What each storey is actually doing to the air, and what to put on it. The weighting looks lopsided written down and is correct — the ground floor is supplying three floors, the top floor is supplying none.
| Floor | What it does to scent | What to put there | Drops |
|---|---|---|---|
| Ground ★ | Exports continuously to two floors above | 3 Sukoons — 2 in the open area, 1 behind a door · ₹5,697 | 3–4 per tank |
| Middle | Receives from below, exports upward | 2 Sukoons, both inside bedrooms · ₹3,798 | 2–3 per tank |
| Middle landing and corridor | Pure through-current | Nothing | — |
| Top | Accumulates everything, exports nothing | 1 Sukoon at most · ₹1,899 — often none | 2 per tank |
| Small shut room on the top floor | Out of the current behind a door | Boond ₹899 (150 sq ft) | 2 per tank |
| Both staircases | Two moving columns of warm air | Nothing | — |
| Terrace or roof door | The only vent in the system | Open it for twenty minutes | Free |
| Six Sukoons is ₹11,394 and includes eighteen 15ml fragrances. For more area add another Sukoon — never a Megh, which costs ₹3,499 and covers 215 sq ft against the Sukoon's 270–320. The Megh is a hundred-hour runtime and humidity machine for one dry room. | |||
Sukoon · five to seven₹1,899Shop → 
Boond · a top-floor room₹899Shop → 
Hotel Collection · one familyFrom ₹299Shop →
Drops, venting and the order the floors run in
Set the doses as a descending ladder: three to four drops per tank on the ground floor, two to three on the middle, two at the top. That gradient is not aesthetic preference, it matches what each floor is receiving for free. If your top floor feels crowded, take the ground floor down to three drops before you touch anything on the top floor itself — in a three-storey house the lower floors are the input and the top floor is only ever the output. The same applies to run time: shorter downstairs sessions reduce the top-floor load far more effectively than shorter top-floor ones.
Placement follows the current. Ground-floor machines go as far from the stair foot as the room allows, about a metre off the floor, and in a double-height living room at seating height rather than on anything high. Middle-floor machines go deep inside bedrooms, away from the landing door, because the corridor is through-traffic for air as well as for people. Top-floor machines go into the room furthest from the stairhead. And nothing at all goes on either staircase — two flights means two rising columns, and a diffuser in a moving column of air is the least productive place a machine can stand.
Ventilation is the tool a triplex has that smaller homes do not. Roof access, a terrace door or a stairhead window at the top of the column will vent the entire house in about twenty minutes if you open it, because you are giving the stack somewhere to go. Use it in the evening before you run anything, not after. Then run the floors in order — ground first on a two-hour timer, middle an hour later, top last and briefly — so each floor is joining a settled state rather than an active one. Rinse tanks between fragrances and use filtered water in hard-water cities.
What a triplex costs
Every tier with the arithmetic shown, and each Sukoon includes three 15ml Hotel Collection fragrances of your choice — so a six-machine triplex arrives with eighteen bottles.
| Setup | What you get | Covers | Total |
|---|---|---|---|
| Ground floor only | 3 × Sukoon ₹1,899 · includes 9 × 15ml scents | The floor that supplies the house | ₹5,697 |
| Ground and middle | 5 × Sukoon ₹1,899 — 3 down, 2 middle · includes 15 × 15ml | Two of three floors, properly | ₹9,495 |
| The full triplex ★ | 6 × Sukoon ₹1,899 — 3, 2 and 1 · includes 18 × 15ml | All three floors | ₹11,394 |
| A large triplex | 7 × Sukoon ₹1,899 — 4, 2 and 1 · includes 21 × 15ml | Bigger ground floor, more bedrooms | ₹13,293 |
| Very large open ground floor | 1 × Vaayu ₹11,999 — waterless, neat oil, cannot use the Hotel Collection — + 3 × Sukoon ₹5,697 | Open volume below, bedrooms above | ₹17,696 |
| Running, per year | Two 300ml bottles at ₹1,799 (~₹6/ml) | Six machines, three floors | ₹3,598 |
Versailles
The three-floor houses I have worked in are almost all in Bengaluru and Hyderabad, and the complaint is identical every time: the top floor smells of the kitchen, or of last night, or of something nobody can name. The owner has usually bought a machine for that floor and is asking me which fragrance will fix it.
None of them will, because the top floor is not producing the problem. It is the end of a pipe. Two floors of a house have been feeding a rising column all day and the top storey is where that column stops. The first thing I do is turn the ground-floor machines down a drop and shorten their timer, and the second is to ask whether there is a door to the terrace. There usually is, and nobody has thought of it as part of the scent system, which it absolutely is — twenty minutes of that door open in the evening resets the whole house.
So: five to seven machines, weighted steeply downwards, a descending ladder of drops from ground to top, nothing on either staircase, and a vent at the top you actually use. If you buy one machine fewer than you planned for the top floor, you have understood this correctly. A portion of every order supports girl-child education through Nanhi Kali.
Frequently asked questions
- How many diffusers do you need for a duplex? — the two-floor version of this.
- Should both floors of a duplex smell the same? — the shared-note rule.
- How many diffusers do you need for a villa? — when the house spreads instead of stacking.
- Complete duplex and multi-floor buying guide — everything in one place.
- Brand: the SOSA founder story.
SOSA products & prices (verified August 2026): Hotel Collection water-based ultrasonic diffuser fragrance 15ml ₹299 · 100ml ₹999 · 300ml ₹1,799 · Pack of 7 (15ml, all fragrances) ₹1,799; refills 100ml from ₹999. Seven scents: The Ritz-Carlton-inspired (white tea · bergamot · cedar), Westin-inspired (white tea · aloe · cedar), 1 Hotels-inspired (cedarwood · vetiver · green leaves), The St. Regis-inspired (amber · violet · woods), Shangri-La-inspired (jasmine · green tea · white tea), Four Seasons-inspired (citrus · floral · sandalwood), W Hotels-inspired (citrus · pepper · amber). Diffusers: Boond 300ml ₹899 · Sukoon 500ml ₹1,899 · Megh 6L ₹3,499. Water-based, phthalate-free, composed to IFRA standards for home diffusion; 3–6 drops per tank. Made in India, Pune. The Hotel Collection scents are SOSA's own interpretations inspired by the world's finest hotels; all hotel names are trademarks of their respective owners and are used only to describe the scent style — SOSA is an independent Indian fragrance house, not affiliated with or endorsed by any hotel brand. Prices and availability subject to change — see the live product pages.