When you live in areas of the country where there is likely to be snowfall, tiny house design needs to consider the snow load for that area of the country.  Snow loads are figured in pounds per square foot.  I found the information on this page by Googling “Wisconsin Snow Loads.”  The following map is from the State of Wisconsin Structural Design Code.  The URL is:

http://dsps.wi.gov/sb/docs/sb-CommercialBuildingsCodeEnrolledReplacV1C.pdf

I am located in Dane County Wisconsin which is the county second from the bottom in the center of the state.  As you can see, the snow load that needs to be considered in structural design is 35 psf.

Of course this structure is on wheels.  Just to the northwest of Dane County is an area where the snow load requirement is 40 psf.  Travel beyond about 75 miles north of madison and the snow load requirement is 60 psf.  At this point we aren’t sure where our trailer is likely to be parked during the winter.  It makes sense to design the structural components to carry a 60 psf load.

As the show load requirement goes up, the structural timbers necessary to support the load go up with the requirement.  This will affect the floor joists, the size of headers over openings like windows, doors, long horizontal windows in dormers, tire fenders, and the size and spacing of rafters and cross ties.

Increasing snow load capacity has tradeoffs in the areas of cost, weight, head clearance in the loft areas of the first floor, and the loft itself.

Now that I know snow load capacity requirements, I need to do additional research into the effects on sizing of structural components.