avoiding building codes with wofati/oehler tiny house

I'm going to build a tinyhouse on my property (which already has a normalhouse). I'm trying to squeeze thru the local code loophole where I can build a structure under 100 sq/ft without permits and taxes. Well, really that loophole is my fallback... First I'm hoping that nobody finds it, even though I live in an urban area.

Beside all the typical advantages to building underground, I figure that it will especially suit my situation for these additional reasons:

- Typically an inspector would measure the outside of the building to see if it stays under 100 sq/ft. Underground he doesn't really have this option...

- I want it to be well insulated, but I don't want to waste my precious square footage on thick, above-ground walls. Using the PSP method, the walls are thin, but all the earth around the building takes care of insulating.

- I can add protruding secret closets beyond the 100 sq/ft unnoticed.



Here's the design I came up with. It will be built with un-milled logs, but flat surfaces were easier to work with in sketchup. The pink areas on the wings are the "secret closets". The site is on a hill sloping down to the south, with the privacy mostly to the south. It will of course be covered in earth, but these pictures don't really show that...

Any advice would be very much appreciated. I relish the opportunity to tap the collective brilliant mind of permies. Thanks.

Looks like a fun project Jon. I would challenge a couple of your assumptions. An inspector could still measure your project from the inside. I dont really see this project as something that would garner the attention of most building depts but since youre in an urban area, better be careful.

I know its debatable, but in a heating climate the ground is going to rob your structure of heat, not insulate it. Whether it makes sense to insulate your below grade walls depends on lots of variables.

Not sure if the hidden aspects of your project negate it but the slope to the south makes it a great candidate for passive solar design.

Keep us posted with pics!

Thanks for the thoughts. I definitely don't know what I'm doing, so I truly appreciate warnings and advice from you all.

- I'm going to keep the interior dimensions within 100 sq/ft so that even if an inspector measures inside, I will be safe within the loophole. The "secret closets" will be concealed so the inspector won't find them.

- I'm counting on the dry earth to give "annualized thermal inertia" as paul calls it in his wofati article, or "passive annual heat storage" as john hait calls it.


My biggest question is whether this roof design will work well. I know Mike Oehler is a bit cautious about gable roofs. Mine is like a pitched gable. The whole roof pitches downhill, while the gable pitches to the sides. Do you guys think this roof looks effective? Will it present any extra construction challenges?

I'm also exploring what the best way to build the footings is in my Post in ground techniques thread.

I love the design and I do think it conforms with Oehler's main requirement(all drainage is hitting earth.). The reason he states that he does not use a pitched roof is that it's more difficult to build. I think the big exception is if you are building on flat land, This design would seem to make more sense as it disperses half of the water over more of the soil.

I'm pretty new to all of this too, so I'm just going with what I've gleaned so far.

Jon Piper wrote:I'm counting on the dry earth to give "annualized thermal inertia" as paul calls it in his wofati article, or "passive annual heat storage" as john hait calls it.

That only works if you have no water getting any where near your structure. Where is your water table? What will you be doing for drainage around your building?

I will do the big poly underground umbrella extending maybe 20ft around the structure. Hopefully that will keep the earth dry.
The roof should shed water far away from the building, and if the uphill patio works the way Oehler says it will, I should be ok. I'm a bit weary of the uphill side. Maybe I can add some drain pipes before backfilling that will bring water from the uphill patio around the structure and down the hill.

The water table shouldn't be a problem.