[Greenbuilding] Hot Tub Building

[Ken Beiser]

While you guys help figure out the energy part, I can pipe in on the 
construction since I have plans to do an indoor tub that will probably 
either be concrete ("ferro-cement") or wood (cold molded fir or cedar).  In 
either case, I planned to insulate it even though it's indoors.  That makes 
it easier to keep a tub of water warm, too.  I am in the foundation stage of 
that timber framed and straw bale wing right now.  I have so many projects 
going on now it is suffering and I hope I do not push myself into the 
winter.  That's when the tub was supposed to happen....between ski trips.

Both techniques are proven in the boat building arena.  The ferro-cement is 
actually easier and can be pretty free form.  Not really that much concrete 
when push comes to shove.  The idea is to make a form and stretch chicken 
wire over it in multiple layers tied together and then pull the form and 
"plaster" from the inside and out at the same time.  Many owner-builder 
boats were built that way in the 70's and even to recently.  They do not 
have good resale however.  Huge recreational vessels have been done this 
way.   I looked at a 72 foot Herschoff square rig design in Grenada.  All 
the wood on the vessel had termites and almost all neglected vessels 
including fiberglass lose their integrity over time.  This vessel's hull was 
incredibly good.

The other technique using wood strips is a time tested method for boat 
building called cold molding.  While it is considered a wooden boat 
technique. it uses a lot of epoxy for laying up the layers.  It is arguably 
the most maintenance free method of boat construction.  It make a light 
strong vessel, too.  For a tub, it would look like the inside of a boat and 
could be finished bright (clear coat with varnish).  It would look great but 
it is a little less free form and uses epoxy which is a "little" toxic and 
some people get allergies to it.

I have also thought about an outdoor hot tub but more like a hot spring.  I 
was thinking of digging a hole and spraying urethane foam over it and 
applying my mesh (chicken/poultry wire) and then plastering with a cement 
stucco mix and throwing in some rock ledges etc for "comfort" and looks. 
Another one of those projects I would love to do but probably will die 
before I can.  At least I will never get bored.

Let me know what you all think!

Ken
Whitefish, MT