Exostack hardware is genuinely cheaper than an insulated stainless stack. But the larger part of the difference is not hardware at all — it is the crane, the secondary steelwork, the extra site visits and the permits that a 900 kg stack drags along behind it. Below is the whole build-up, on both sides, with nothing rolled into a lump sum.
Set the geometry and the roof, choose what you are comparing against, and the model rebuilds both estimates line by line. It runs in your browser — nothing is sent anywhere.
2025 German market rates · indicative, not a quotation
Measured from the roof deck to the head of the stack.
Nominal bore of the flue path.
85% less than double-wall insulated stainless 316L, delivered and installed.
A 7 m × 1,000 mm stack on trapezoidal steel sheet decking, the most common industrial rooftop situation in Europe. Both bars are drawn to the same scale.
Saved on this reference installation — an 85% reduction on delivered project cost. Two thirds of it is hardware; the rest is crane, secondary steelwork, extra site visits and permits that simply never enter the programme.
Roof reinforcement is €19,500 on this reference case and it is almost never in the first budget, because it only appears once a structural engineer has looked at the deck. On trapezoidal sheet it is the single largest surprise in a conventional stack project, and on Exostack it does not exist — the guy wires spread the wind moment across three anchor points instead of concentrating it at a base plate.
On a concrete deck that needs no reinforcement, and against a single-wall rather than insulated stack, the gap closes considerably. Set the calculator above to that case and you will see it honestly: the saving is smaller, and it is still worth having. We would rather you found that out here than felt misled later.
An Option B duct lasts 12 to 18 years, so a 20-year horizon usually includes exactly one replacement. That is a planned four-hour job on a skeleton that stays standing, and we put it in the total rather than leave you to discover it.
The honest comparison on the other side is not a stack that needs nothing for 20 years either. Rigid stainless typically wants relining or recoating around year 12, and that means a crane, a shutdown and a five-figure invoice.
| Over 20 years | Rigid 316L | Exostack B |
|---|---|---|
| Initial installation | €84,650 | €12,503 |
| Duct replacement, year 15 | — | €5,028 |
| Reline or recoat, year 12 | €8,000 | Not required |
| Crane for mid-life work | Included above | Not required |
| Production downtime | 2–3 days | 4 hours |
| Annual inspection | Specialist visit | 30 min, in-house |
| Twenty-year total | €92,650 | €17,531 |
If you switch fuel or add a scrubber inside those 20 years, the rigid stack is often wrong for the new flue chemistry and has to be replaced outright. Exostack takes a different duct on the same skeleton for the price of the duct.
An 85% saving is a large claim and you are right to interrogate it. Here is the basis, so you can check it against your own quotations rather than take ours.
The stainless figures are supply prices for CE-marked, insulated double-wall stack from established European manufacturers — what a contractor actually invoices. They are not raw 316L tonnage rates, which would understate the comparison and flatter us.
Crane hire, rigging, structural steelwork and installation labour are verified 2025 rates for the German market. Rates in other European markets and the United States differ, sometimes materially, and we re-run the model per project.
Everything is normalised to 7 m × 1,000 mm on trapezoidal sheet, then scaled: skeleton cost with height and diameter, duct with developed area, reinforcement with system weight. The calculator applies the same scaling you see here.
No allowance for road closure, out-of-hours working, scaffolding or production downtime during a conventional install — all of which are real, all of which favour Exostack, and none of which we have counted.
Coated fabric pricing spans a wide range by source and grade, which is why replacement costs are quoted as ranges rather than points. Reinforcement cost varies with the specific deck and frame more than any other line.
If you hold a real quotation that contradicts a figure on this page, we want to see it. Either it improves our model or it tells us something about your market we did not know. Both are worth more to us than being right.
Send it to engineeringThe calculator gets you within a working range. To get a figure you can put in a budget submission we need the stream, the geometry and a look at your roof — which is four short steps and a two-day turnaround.