Cold plunge
Cold plunge floor load: weight, footprint and when to call an engineer
Plunge currently lists the All-In at 1,150 lb filled over a footprint of about 16.8 sq ft, or roughly 68 lb per square foot averaged over that footprint. That is not a pass/fail comparison with the IRC's 40 psf room live load — the two describe different loading cases. On an elevated wood-framed floor, joist span, spacing, orientation, species and grade and the support conditions are the questions that decide it.
Short answer. On a concrete slab on grade, weight is rarely the question that decides it. On an elevated wood-framed floor it is: 1,150 lb standing over about 16.8 sq ft has to be carried by particular joists, and only a structural engineer or another qualified building professional can tell you whether yours carry it. That answer is worth having before delivery rather than after.
The arithmetic
Plunge publishes the numbers for its All-In model, so the figures below are theirs rather than a generic estimate.
| Published figure | Value |
|---|---|
| Footprint | 76¾ × 31½ in |
| Water capacity | 105 gal |
| Weight, empty | 238 lb |
| Weight, filled | 1,150 lb |
| Footprint area | 16.8 sq ft |
| Average pressure on the floor | ≈ 68 lb / sq ft |
The 2024 IRC design live load for habitable rooms is 40 psf, and 30 psf for sleeping rooms. Those two numbers get put next to each other constantly, and the comparison is not a valid one.
"But a bathtub is heavy too"
It is the first thing everybody says, and it is worth taking seriously rather than waving it away. A filled bathtub is a comparable load, and bathrooms do not collapse. Two things differ. A tub is shorter, so its load lands across a different length of span. And the room it sits in was framed knowing it was going there, whereas a plunge arrives into a room that was designed without it. If your engineer looks at the span and the support conditions and says it is fine, it is fine. The question is not whether the load is enormous, it is whether anyone has checked it in this room.
Where the question changes shape
On a ground-floor concrete slab, on a patio, or outdoors on grade, the question usually shifts from joist capacity to slab or base condition and to the manufacturer's placement requirements — which is a large part of why so many of these end up outside. If your deck is a raised structure rather than a ground-level platform, you have moved the same question to a different framing member rather than removed it. Ask about the deck too.
The electrical side, and a manufacturer contradicting itself
Dated discrepancy. Plunge's support article specifies a dedicated 20 A circuit for the same model. It is kept here as an earlier document rather than presented as equally current: if your unit's nameplate says 20 A, size to the nameplate.
A plunge is a smaller electrical problem than a sauna: 15 A or 20 A at 120 V rather than 20–50 A at 240 V. If you are planning both in the same room, the home sauna electrical requirements page carries the 125 % continuous-load arithmetic and the NEC 220.83 capacity check that the sauna side turns on.
Across their documentation:
- All-In: dedicated 15 A on the current product page; 20 A in the older support article (checked 2026-09-06)
- Evolve Standard: dedicated 15 A
- Evolve Pro: dedicated 20 A
- Plunge Gen 1: dedicated 20 A
- GFCI-protected cord supplied with all models
- Extension cords prohibited on every model — which quietly means the outlet has to be where the tub is, and that is another electrician conversation
These are modest loads compared with a sauna heater. The word doing the work is dedicated: it is a new circuit, not a spare outlet. If you are already having a sauna circuit run, having both done in one visit is the obvious economy. The planner will fold both into one estimate.
Chiller sizing, and why this site will not give you a formula
Plunge publishes real performance figures for the All-In: a 0.75 HP chiller rated to hold 37 °F in an ambient of 120 °F, cooling at 10–12 °F per hour and heating at 4–5.
What you will also find online is a set of rules of thumb — one horsepower per 150 to 250 gallons depending on how aggressively you want it to pull down, roughly 9,000–10,000 BTU per horsepower, derated 15–25 % as ambient temperature climbs from 70 °F to 95 °F. Those figures come from retailer and community sources, not from chiller manufacturers.
They are probably in the right neighborhood. They are still not presented here as engineering, because the whole point of this site is that the numbers on it have somewhere to point back to. If you are buying a chiller separately, give the manufacturer your water volume, your target temperature and your worst-case ambient, and make them size it.
Who should ignore this page?
Not everyone needs a floor-load page. If the plunge is going on a slab on grade, or outdoors on a prepared base, the structural question here mostly does not arise — the manufacturer's placement requirements and the circuit are what to read instead. This page is for someone putting a filled plunge on an elevated wood-framed floor: a second story, a room over a basement or crawlspace, a deck.
Three price points
The same logic as the sauna cost page applies here: the listed price is the part of the total that varies least.
Plunge All-In
$7,990 (from $9,990) — 105 gal, 0.75 HP integrated chiller, the published performance figures above. The premium option, and the one whose numbers I have actually been able to check.
View current listingSun Home Cold Plunge Pro
$13,899 (from $14,499) — 150 gal, 34×78×33 in, 120 V / 12 A on an 8 ft cord, 30–55 °F range. More water, more money.
View current listingRedwood Outdoors Alaskan
$2,999 — 130 gal, 37 in diameter, 250 lb dry. No chiller and no outlet. You supply ice. It removes the electrical question entirely and costs a third of the All-In, at the price of a daily errand.
View current listingThe ice-based option is the one I would suggest to anyone who has not already established the habit. Several thousand dollars of chiller is a lot to spend on a routine you have not yet proved you will keep, and the resale market for barely-used recovery equipment is not kind.
On the health question. This site does not make health claims about cold water immersion, and you should be skeptical of any site that does. Cold immersion carries real cardiac risk for some people, the cold shock response is a genuine drowning hazard, and none of that is settled by an internet article. Talk to a doctor. What this site can help with is whether the thing will fit, what it weighs, and what it needs to plug into.
How this page was researched
The weight, footprint and circuit figures come from each manufacturer's current product page, read on the date shown beside them. Where a manufacturer's own support article disagrees with its current product page, both are shown and the older one is marked as dated rather than quietly dropped. Nothing here is a structural calculation. These are the inputs a professional works from, not the answer.
| Source class | What it carries on this page | Last re-read |
|---|---|---|
| Manufacturer product page | Filled weight, empty weight, footprint, volume and the dedicated circuit | 2026-09-06 |
| Manufacturer support article older than the product page | The 20 A figure, kept as a dated discrepancy rather than deleted | 2026-09-06 |
| Code text | The IRC design live load, quoted for what it is and explicitly for what it is not | 2026-09-06 |
| Retailer and community source named as such, not used as engineering | The chiller rules of thumb, which is why this page will not turn them into a formula | 2026-09-06 |
| Editorial calculation | Pounds per square foot averaged over the footprint. Calculated here, and not a structural verdict | 2026-09-06 |
What changed
- 2026-09-06 — the headline was changed from a claim that a filled plunge weighs more than your floor is rated for. Averaged pounds per square foot is not a pass/fail comparison with the IRC's room live load, and the page now says that before it says anything else.
- 2026-09-06 — four assertions that could not be supported were deleted, including a claimed factor of safety and a claim about where bathtubs sit relative to structure.
- 2026-09-06 — the Plunge All-In circuit was updated to the current published 15 A. The 20 A figure from the support article moved into its own dated-discrepancy note.
Sources. Plunge All-In current product page · Plunge electrical requirements (support) · IRC 2024 R301.5 floor live loads · Sun Home Cold Plunge Pro · Redwood Alaskan · Chiller sizing rules of thumb (community source, not a manufacturer).