Designing a Mobile Sauna Under 2,000 Pounds

In recent years mobile saunas have picked up steam. Recently this post on Reddit really sucked me in. Living south of Boston with so many great beaches, kettle ponds, and lakes I can’t help but scrap all my ideas for a sauna building and go deep on mobile.

Our first month of the year “January” dip into the lake and another adventure with my wood burning mobile sauna!

A few weeks ago I was scoping out the true cost of an 8×12 sauna building (on land, not a trailer) using the Sauna Times plans. At the time I quickly looked at what it would cost to make it mobile and with large enough trailers being $3,000 or more, I let it go. But by downsizing from 8×12 to say 5×8 or 6×10 the cost of the trailer drops to about a third.

After some digging around it looks like Tractor Supply is the best place for trailers near me. They deliver them free to your local store and there’s one half an hour from me. They’ve got a 5×8 trailer for $899 and 6×10 for $999.

At first I was wishfully thinking I could build a sauna-and-changing-room-combo building but weight is a huge constraint unless you have a legit truck. My wife and I have a Jeep Wranger and RAV4 Hybrid. Both vehicles max out at about 2,000 pounds tow capacity. The Rav’s official tow capacity is 1,750 but this Youtuber had good luck going through mountains with a 2,000 pound load. For a few moments I entertained getting a(n also tiny) pick up truck but it’d be a little too crazy to get a truck specifically for sauna.

This 4×4 Ford Ranger from ’99 towing a dark green sauna would look mint. If it’s got the tow package it can handle a load just under 6k pounds. $3,400.

With loads of optimism I fired up Google Sheets, thinking for sure I can build a 6×12 sauna with a changing room on one of these tiny trailers. Using this handy wood species calculator and weight details from product pages, I came up with some early estimates. It looked like a 6×12 build would be about 2,500 pounds. With my poor estimation skills it’s probably more like 3,000. I tweaked the sheet to allow for experimenting with various dimensions.

I realized I can’t go any bigger than 6×9 which means no changing room. It’ll have to be the car or a pop-up shower tent!

Assumptions and iffy bits:

  • I’ll use clear tongue & groove white pine on the inside. It’s local, it’s cheap ($1.20 per SF), and I’m looking to do this build on a low budget.
  • I’m guessing removing the trailer gate saves me 200 pounds.
  • I haven’t quite finalized the floors but given the trailer itself has a deck I doubt I’ll put in a full platform with 2×6 rafters and all. This is missing from the cost and weight estimates. I wonder if I can get away an uninsulated floor and basically bolt 1/2″ plywood on top of the trailer deck, covered in cement board.
  • LP SmartSide panel is the lightest siding after vinyl, looks decent, and lasts a while. I’d love to use local rough-cut pine but makes my siding almost 600 pounds vs 400. Plus the rough cut pine is likely to be green and even heavier.
  • I’ve no idea about the cost and weight of the roofing.
  • I’m using seagrass for insulation and the weight at 100 pounds is a wild guess.
  • I haven’t built in the weight of the door, windows, hardware, bolts for securing the building to the trailer, nails and probably a few other things.

I’ll probably end up shooting for 6×8. Even that’s a stretch at an estimated 2,133 pounds.

I’m tempted to follow my buddy Sauna Matt’s advice from a phone call this morning: Buy the trailer and get started. Maybe I’ll end up in that red pickup after all.

The estimates are easiest to to see in Google Docs. You’re welcome to grab a copy and play with it by going to File > Make a Copy.

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