Straight answers
What do off-grid house plans leave out?
A plan set specifies the building. It cannot tell you whether you may build it where you are standing, or whether its systems will work on your site, because both are decided locally. Four things sit outside every plan set: whether zoning permits the dwelling at all, whether the building code in force where you are permits the water and waste systems drawn, whether the health authority will approve on-site sewage, and how large the array and battery bank have to be for your winter rather than for an average one.
Figures verified against the sources below · September 11, 2026
01 — The longer answer
Zoning decides the dwelling; the drawing does not
Zoning governs whether a dwelling is permitted on the parcel and in what form, and that is settled before any drawing matters. In the Thompson-Nicola Regional District in the BC interior, the zoning bylaw prohibits recreational vehicles as dwellings in every zone, including on a temporary basis, while a modular home on a foundation is treated as a building. A plan set for a home on wheels is not the problem there. The format is.
The code in force is local, and some places adopt none
Wyoming's statewide adoptions cover public, business and industrial buildings and do not include the IRC, so whether a residential code applies to a house is a local decision there. Montana adopted the 2021 I-Code series statewide, with IRC Appendix Q for tiny houses of 400 square feet or less excluding lofts, under ARM 24.301.154. A plan drawn to one code edition in one state is not automatically permittable in another.
Sewage is a separate approval from the building permit
In British Columbia an on-site system falls under the Sewerage System Regulation, which is a different authorization from the building permit and turns on what the ground will accept. Choosing a composting toilet does not remove the requirement to deal with the rest of the wastewater. No plan set can promise that approval, because it is granted against the site rather than the drawing.
The structural and climate values are per-site
Frost depth, design roof snow load, wind speed and seismic category govern the footings, the roof and the connections, and they change by state and often by county or elevation. A plan set bought off a catalogue carries someone else's values. The state guides on this site publish the code in force and the design figures for each state, with the source for every figure, so you can check what your build actually has to meet.
Sizing comes from your site, not from the plan
The array follows from your daily consumption in kilowatt-hours, the usable sun hours at your location and a system derate for inverter, wiring and temperature losses. The battery bank follows from how many days you want to run without sun. Two identical homes on different sites need different systems, which is why capacity is specified at design time rather than taken off a package list.
Do you sell off-grid house plans?
No. We build finished homes rather than selling plan sets, and the design work happens as part of the build, with the power, water and waste systems specified before construction starts. If what you want is drawings to hand to your own builder, that is a plan publisher's product and not ours.
03 — Sources
Each figure above links to the authority it came from.
TNRD Zoning Bylaw No. 2400, consolidated to 13 August 2026, s.3.18.2: recreational vehicles and tents are not buildings and are prohibited as dwelling units in all zones, including on a temporary basis
tnrd.civicweb.netWyoming State Fire Marshal statewide adopted codes: the IRC is not among them, so residential code adoption is a local decision
wsfm.wyo.govMontana adopted the 2021 IRC with Appendix Q statewide under ARM 24.301.154 (tiny houses 400 sq ft or less, excluding lofts)
law.cornell.eduBritish Columbia Sewerage System Regulation (BC Reg 326/2004) under the Public Health Act governs on-site sewerage systems
bclaws.gov.bc.ca
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