For many of our trailers, you have a choice when it comes to the axles. These choices can include ‘drop axles’ and higher capacity axles.
Drop axles are special axles that allow the deck (or top surface) of a trailer to be between 3 to 4 inches lower. This can be especially useful for tiny houses since there is a cap on the total height of your house, usually 13.5 feet. Thus the only way to gain additional interior height is the lower the deck. That doesn’t mean that drop axles are required though. When we build our houses we don’t normally use drop axles and we still have a comfortable amount of height both above and below our lofts. On the down side, drop axles reduce the ground clearance of your trailer. This is less of a concern for shorter trailers but can become more of an issue on longer trailers. Finally, because of the way drop axles work, they take up a little more room between the wheels and so there is a little less space between the fenders.
When it comes to axle capacity, all of our trailers include axles that are rated to exceed the anticipated weight of your house. For our 20 foot and shorter trailers, we use two 5200 lbs. axles which gives the trailer a capacity of about 10,000 lbs. (GVWR). For our larger trailers we use either 2 or 3 7000 lbs. axles for a total weight capacity of between 14,000 and 21,000 lbs. It’s unlikely that you would need to upgrade the capacity of your axles unless you plan to build a house that you expect to be much heavier than a typical house of its size. An example of this would be if you were building a house that was to be used as a food truck.