Finnmark FD-7 Thermo-Aspen – Outdoor Hybrid Infrared & Traditional Barrel Sauna (6x6)

Finnmark FD-7 Thermo-Aspen: The Low-Maintenance Outdoor Barrel Sauna

The Finnmark FD-7 is a 6x6 outdoor barrel sauna built from 1.5" full-length Thermo-Aspen staves with a Canadian Cedar interior. It seats four, reaches 185°F, and combines Spectrum Plus™ infrared panels with a traditional rock heater.

It is the same barrel as the cedar FD-6 in every functional respect — same dimensions, same heating systems, same manual. The difference is the exterior wood, and if you have been trying to work out what "thermo-aspen" actually means, that is the question worth answering first.

What Thermally Modified Aspen Actually Is

Thermo-aspen is aspen that has been heat-treated at high temperature in a controlled, chemical-free process. The heat alters the wood's cell structure, and the result differs from untreated wood in ways that matter outdoors:

• It absorbs far less moisture. The treatment reduces the wood's ability to take on water, which is what causes swelling, warping, and cupping in outdoor timber.
• It is dimensionally stable. Less movement through wet and dry seasons — useful in a barrel, where staves are held in tension against one another by stainless bands.
• It resists decay without chemicals. Where cedar relies on natural oils, thermal modification removes much of what fungi feed on.
• It is pale and warm-toned rather than the reddish-brown of cedar, giving a lighter, more contemporary look.

Thermo-aspen tends to ask less of you over time than untreated softwood. That said, Finnmark's warranty still requires wood preservative on all exterior surfaces after installation — see below.

Wood Care and Your Warranty

This is the most commonly missed requirement on outdoor barrels, and it applies to the FD-7 as much as the cedar FD-6.

Finnmark's warranty excludes damage caused by failure to apply wood preservative to all exterior surfaces immediately after installation, including doors and windows. Thermal modification improves the wood's natural resistance, but it does not remove this obligation.

Coverage also excludes damage from failing to keep the barrel on a flat, level, hardtop surface with adequate drainage, and from failing to keep the exterior clear of plants, trees, grasses, soil, and snow deposits.

Budget the preservative into your installation. Ask us and we will tell you what Finnmark recommends for thermo-aspen.

FD-7 or FD-6? An Honest Comparison

	FD-6 Cedar	FD-7 Thermo-Aspen
Exterior wood	Canadian Red Cedar	Thermo-Aspen
Interior wood	Canadian Cedar	Canadian Cedar
Appearance	Warm reddish-brown	Pale, contemporary
Decay resistance	Natural oils	Thermal modification
Scent	Strong cedar aroma	Milder (cedar interior still scents the cabin)
Preservative required	Yes	Yes
Size, heating, features, manual	Identical

Worth noting: the FD-7's interior is still Canadian Cedar, so you get the cedar scent inside regardless. The choice really is about the exterior appearance and how you want it to age.

Hybrid Heating

The FD-7 runs two heat sources:

• Finnmark Spectrum Plus™ infrared panels (UL-Listed, third-party tested) for lower-temperature, directly penetrating heat.
• A traditional rock heater for authentic Finnish steam — ladle water onto the stones for humidity.

Outdoors in a northeastern winter, that flexibility earns its keep. Bringing a barrel up to full traditional temperature takes real time on a January evening. The infrared panels give you a usable session sooner, while the rock heater delivers the complete experience when you have the time.

Maximum temperature is 185°F. The infrared heaters shut off at 170°F by design when running alongside a traditional heater.

Electrical Requirements

Finnmark's manual lists the FD-7 barrel's own requirement as 15 A / 120 V / 1750 watts, which covers the infrared system and controller.

Your traditional rock heater is a separate unit with its own supply requirement — a 4.5 kW heater such as the HUUM DROP typically needs a dedicated 240 V circuit. The exact figure depends on which heater you choose, so confirm it against that heater's specifications.

For an outdoor installation this means getting power out to the sauna — buried conduit or an exterior run with weatherproof connections, installed by a licensed electrician per NFPA 70. Finnmark requires professional installation and all wiring by a licensed electrician following local codes. In New York City this generally requires permits. Have the run quoted before you order; the distance from panel to sauna is usually the biggest cost variable in the whole project.

Siting and Foundation

• Base: Finnmark specifies a flat, level surface — concrete, gravel, or wood decking. Over grass or organic ground, place pavers or flagstone under the cradles to prevent sinking.
• Drainage: the manual specifically calls for proper drainage in heavy-snow regions, which includes the New York area.
• Clearance: leave access around the barrel for airflow and maintenance.
• Cover: position under an awning or overhang where possible to keep heavy rain off the roof.
• Permits: check with your local buildings department before construction.

Assembly: What It Actually Involves

Finnmark requires professional installation and a minimum of two physically able people. The barrel arrives as components for on-site assembly across roughly two dozen steps — cradles, drain assembly, staves, front and back panels, benches, stainless bands, trim, rain wedges, heater connections, rainguard membrane, and shingle roof.

Tools needed: impact driver, circular saw, hand sander, chalk line, tape measure, 4 mm allen key, adjustable wrench, rubber mallet, 3 ft level, and a step ladder. A level and pencil are included in the accessory box.

Most buyers hire a contractor. If you are handy and have a second person, it is achievable, but it is a full project rather than an afternoon.

Features

• Construction: 1.5" thick full-length Thermo-Aspen staves, FSC certified.
• Interior: Canadian Cedar dual-level benches with backrests.
• Controls: Wi-Fi LCD touchscreen via the Smart Life app — start the heat-up from indoors, schedule sessions, and set temperature and lighting remotely.
• Lighting: RGB under-bench mood lighting with selectable colours, including a red setting usable for red light therapy during sessions.
• Glass: 8 mm tempered glass door and window panels.
• Roof: rainguard membrane and full shingle roof kit included.
• Safety: UL-Listed and ETL-certified components, third-party tested heaters, 2024 Safety Award recipient.

Specifications

Specification	Details
Model	Finnmark FD-7 Thermo-Aspen Combination Barrel Sauna
SKU	FD-KN007
Sauna Type	Hybrid — traditional rock heater + infrared
Capacity	4 persons, dual-level benches
Dimensions	6' x 6' barrel
Exterior Wood	Thermo-Aspen, 1.5" full-length staves
Interior Wood	Canadian Cedar
Heating	Finnmark Spectrum Plus™ infrared + traditional rock heater
Heater Option	HUUM DROP 4.5 kW (sold separately)
Temperature Range	Up to 185°F
Barrel Electrical	15 A / 120 V / 1750 W (traditional heater supply is separate)
Control Panel	Wi-Fi LCD touchscreen, Smart Life app
Lighting	RGB under-bench mood lighting
Door & Windows	8 mm tempered glass
Placement	Outdoor
Shipping Weight	Approx. 953 lbs across 3 crates (287 / 234 / 432 lbs)
Included	Shingle roof kit, rainguard membrane, stainless bands, drain assembly, level, pencil
Sold separately	Heater, sauna stones, Wi-Fi controller

Warranty Coverage

Component	Coverage
Spectrum+ heaters	Lifetime
Carbon heaters	10 years
Craftsmanship	10 years
Electrical components	10 years
Audio components	10 years
Lighting remote	1 year (accessory)
Commercial use	5 years

Warranty applies to the original retail purchaser and is not transferable. Replacement-component shipping is covered within 30 days of receipt; after that it is the customer's responsibility. See the manual for full terms and exclusions.

Product Manual

Download the Finnmark FD-6 / FD-7 barrel sauna installation manual for the complete step-by-step assembly sequence, parts list, controller and Wi-Fi setup, safety precautions, troubleshooting, and full warranty terms. Worth reading before your barrel arrives, particularly the foundation and wood-preservative requirements.

Shipping & Delivery

Freight cost: This product ships free to the contiguous United States. Canada is $490. On rare occasions, remote or complex delivery areas may not qualify for these rates — if that applies to your address, we will contact you before processing the order.

Delivery is curbside by freight carrier in three crates totalling roughly 953 lbs. Plan this properly: have help or equipment arranged, the route from curb to final position cleared, and your foundation finished before delivery day.

Inspect the crates and document any damage on the delivery paperwork before signing. Freight claims are far easier to resolve with damage noted at delivery.

Frequently Asked Questions

What is not included with the FD-7?

The heater, sauna stones, and Wi-Fi controller are sold separately. The barrel is pre-fitted to accept a traditional steam heater but does not come with one. Contact us for a complete package quote so nothing is overlooked.

Is thermo-aspen better than cedar for an outdoor sauna?

Neither is better — they resist decay by different mechanisms and both perform well outdoors. Thermo-aspen is more dimensionally stable and paler in tone; cedar has natural oils and the classic aroma. Both require wood preservative after installation to maintain warranty coverage. Choose on appearance.

Do I really need to apply wood preservative?

Yes, and immediately after installation. Finnmark's warranty explicitly excludes damage caused by failing to apply preservative to all exterior surfaces, doors and windows included. Thermal modification helps, but it does not exempt you from this requirement.

Does the FD-7 still smell like a cedar sauna inside?

Yes. The interior benches and backrests are Canadian Cedar, so you get the cedar scent during sessions regardless of the thermo-aspen exterior.

What foundation does it need?

A flat, level surface — concrete, gravel, or wood decking. Over grass or organic ground, place pavers or flagstone under the cradles to prevent sinking. Allow for drainage, which the manual flags specifically for heavy-snow regions.

How heavy is it and how does it arrive?

Roughly 953 lbs total, in three crates of 287, 234, and 432 lbs. It arrives as components for on-site assembly, not pre-built. Finnmark requires a minimum of two physically able people and recommends professional installation.

Do I need a permit for an outdoor sauna in New York City?

Often yes, especially for the electrical supply and sometimes the structure itself. Requirements vary by borough and installation type. Check with your local buildings department before you begin.

How long should sessions be, and how often?

Finnmark advises no more than three sessions a week for the first four weeks while your body adapts, moving to daily sessions after about six weeks if you want. Noticeable results generally come from sessions of at least 30 minutes; 45 minutes for therapeutic use. Always hydrate before, during, and after.

Questions Before You Buy?

We are an authorized Finnmark dealer based in Staten Island, New York. If you are torn between the FD-6 in cedar and the FD-7 in thermo-aspen, tell us where the sauna will sit and how exposed it is, and we will give you a straight recommendation rather than a sales pitch.