A chimney does two jobs: it holds itself up, and it keeps the gas inside. Exostack stops asking one wall of steel to do both. An aluminium exo-skeleton carries the load on the outside; a replaceable PTFE-coated fabric duct contains the exhaust on the inside. What arrives is two pallets, not a crane booking.
Complete 7 m × 1 m system. A double-wall stainless equivalent weighs over 900 kg.
Option B, 7 m × 1 m, delivered, erected and commissioned. Against roughly €83,000.
Two engineers, one visit, hand tools. Rigid stacks take three to five days across several.
Every module is under 15 kg and goes up the stairs. No crane, no road closure, no permit.
Ask a plant engineer what a rooftop stack costs and they will quote you the steel. Then the crane, the structural survey, the secondary steelwork and the road closure arrive, and the project is three times the number in the catalogue. That cost structure was built for a world of cheap labour, open crane access and flat concrete decks — none of which describe a modern industrial roof.
A 900 kg stainless stack means a 30–50 tonne mobile crane, a certified operator, two or three riggers and, on a constrained site, a road closure and traffic management plan. That is spent before a single bolt is turned — and on a rooftop the crane cannot reach, it is not a cost at all. It is the end of the project.
€3,500 – 4,500 per liftTrapezoidal sheet decking carries 100–150 kg/m² distributed. A double-wall stainless stack puts many times that through its base plate, plus an overturning moment that has to be traced back to the main frame. The fix is not a detail on a drawing — it is a secondary steelwork package that costs more than an entire Exostack system.
€14,000 – 28,000 in reinforcementAdding two metres to a stainless stack means a fabricated section, a crane and a coded welder: four weeks and five figures. Moving it costs much the same. So most plants quietly live with a stack in the wrong place, at the wrong height, for the wrong process — because changing it is harder than tolerating it.
€4,000 – 9,000 per height changeIn a conventional stack, one wall of expensive alloy resists wind load, carries its own weight, survives the acid and lasts thirty years. Every one of those duties pushes the specification — and the price — in a different direction, and the wall has to satisfy the worst of them all at once.
Exostack splits them. The aluminium exo-skeleton on the outside takes dead weight, wind and guy tension, and never meets the flue gas. The fabric duct on the inside meets the flue gas and carries nothing. Each is specified for one duty, and each is optimal at it.
The consequence is the interesting part: because the duct is not structural, it can be replaced in an afternoon without touching the skeleton — and because the skeleton never meets the gas, it outlives several generations of duct.
| On a working roof | Double-wall SS316L | Exostack |
|---|---|---|
| System mass | 900+ kg | 40 kg |
| Heaviest single part | 180 kg | 14 kg |
| Crane | Always | Never |
| Roof reinforcement | Almost always | Not required |
| Hot work on site | Welding, permit | None |
| Time on site | 3–5 days | 4 hours |
| Change the height later | €4,000–9,000 | Add modules |
| Move it later | €3,000–7,000 | Demount, re-erect |
| Renew the gas-wetted surface | Reline or replace | Swap the duct |
| Installed cost | ≈ €83,000 | ≈ €12,500 |
The aluminium structure is identical across the range — it never touches the gas, so it has nothing to be resistant to. What changes is the duct: its coating chemistry, its temperature ceiling and its abrasion tolerance are matched to the stream you actually have.
The value specification for moderate temperatures and mild chemistry — building and HVAC exhaust, generator stacks, food process ventilation.
Teflon® inert to essentially every industrial acid, Kynar® outside for 25 years of weather. Where most industrial exhaust lands.
Halar® over a Kevlar® base for streams that are chemically aggressive and abrasive at once — etching, plating, fly ash.
Exostack supply is genuinely cheaper — but roughly half the saving comes from work that simply never happens: no crane, no structural reinforcement, no second and third site visit, no permits for hot work. We publish the whole build-up, line by line, including the cost of replacing the duct at end of life.
Two engineers, standard hand tools and a working-at-height ticket. No crane, no welder, no hot work permit, no second trade waiting on the first. The clock on the left is cumulative — read it down and you have the whole day.
Set the base module out, drill through the trapezoidal sheet to the purlin below, and anchor with M16 stainless at 150 mm minimum embedment. Connect the process duct to the low-level inlet.
Each section is under 15 kg and goes up through a standard roof hatch by hand. Flanges align, M12 stainless torqued in a cross pattern, and the seven-metre skeleton is standing. Nothing is lifted mechanically at any point.
Three pre-swaged 6 mm stainless assemblies clip to the integrated eyelets at two-thirds height and run to their roof anchors. Turnbuckles are brought up in sequence with the supplied gauge until the skeleton reads plumb on both axes.
The duct arrives rolled and pre-formed. One engineer receives it at the head while the other feeds from below. Circumferential bands engage at each ring, the inlet collar and head ring are clamped, and the duct takes its cylindrical form as it comes up to tension.
Walk the flanges and seams, verify and log the three guy tensions, check the base for gas-tightness, and complete the installation record — the document the Bezirksschornsteinfeger or your inspection authority will ask for.
The question is never what industry you are in. It is how hot the gas is, what is dissolved in it and what is suspended in it. These are the nine environments Exostack is most often specified into, and the duct each one lands on.
H₂SO₄, HCl and H₂S streams where PTFE replaces an FRP stack at lower installed cost.
Option BNo hot work, no contamination risk, and relocatable when the line layout changes.
Option A or BA non-stick inner surface that grease and condensate do not build up on.
Option A or BRooftop process exhaust on trapezoidal decking without touching the structure.
Option A or BGenerator and UPS stacks installed without lifting plant over a live floor.
Option BFuel switching changes the flue chemistry. Change the duct, keep the structure.
Option CChromic, nitric and phosphoric fume — the duty ECTFE exists for.
Option BSilent, cold installation on an occupied hospital or laboratory roof.
Option AThe only stack designed to be put up, taken down and put up again elsewhere.
Exostack is a new product class, and any engineer specifying it will ask what is certified and what is still in the pipeline. Rather than make you dig for it, the status of every approval is on the page — complete, in progress or planned — and it is updated as each one moves.
Structural design to EN 1993-3-2 and ASCE 7 is complete, and the EN 1443 classification is settled at T260 N1 W. DIBt national technical approval and CE marking are the live workstreams; NFPA 211 and UL 1777 listings follow in the United States.
Four short steps — what the process is, what comes out of it, how big the stack has to be and where to reach you. An engineer reads every one, and if Exostack is the wrong answer for your exhaust we will say so rather than sell you the nearest option.