Tiny House Trailers – How do you find the usable space in a tiny house?

How do you find the usable space in a tiny house?

FYI for your tiny house design – Everyone does things differently in the DIY world, so telling you how much space is going to be inside your tiny house is very complicated.  Here are some of the general measurements and averages you will find in tiny houses.

Width 8 1/2 max = Width of outer walls – 8 1/2 feet Living dimensions average around 7 1/2 feet inside  (12 inches for walls)
Height 13 1/2 max = Ground to top of roof – 13 1/2 feet (162 inches) Living dimensions average somewhere between 9.5 feet – 11.8 feet inside ( 48 inches deck, floor and roof – 20 inches deck, floor and roof ) Allow for the loss of the raised fenders in the floor plan in your design.
Length 12-39 max = Width of outer walls + the length of the trailer tongue (See below) Living space for a trailer that is 39 foot long is around 31 feet inside

Stick your trailers tongue out – A trailer tongue can add an additional 3 1/2 feet and up to 7 feet to the overall length of the trailer dependent on the trailers design.   Length of a trailer is generally advertised as the exact size of the bed.  Often the V of the tongue and fenders are excluded from the trailers advertised length.

The trailer you select can change your usable living space before you begin building – Knowing how trailer lengths are measured and how they can vary based on who sells it or what it was originally designed for.  Most trailer manufactures measure the usable space not actual length and width.   The most common causes of measurement confusion;

  • Enclosed V nose cargo trailers – Measures the forward extension V on the trailers tongue.  With the cargo enclosure removed the trailers usable area is again measured like any other trailer.  A reduction of 2 feet or more.
  • Fifth wheels – Fifth wheels and goose neck trailers used for a tiny house are often measured to include the area covering the fifth wheel.  If they are measured in this way you loose much of the vertical space available on standard pull trailers of when both are measured properly.
  • Travel trailers and other trailers that utilize pull outs or extend the usable space onto the tongue or a rear deck.  When  dismantled the actual usable space is sometimes dramatically reduced.
  • Used trailers are often sold with incorrect measurements.  They may claim the trailers length is from hitch tip to the tail end instead of usable space.  Always measure the usable space yourself or you could pay far too much for a smaller trailer.
Lofts and pull outs increase your living space in a tiny house – Every square foot of living space is critical in every tiny house.  Lofts are a good way to increase living space.  Using more of your vertical space between 9.5 feet – 11.8 feet of inside height.  Pull outs increase living space without the loss associated with additional ceiling, frame, floor thickness needed for a loft.
Trade some vertical space to gain a lofty increase in your living space – You loose on average around 8 inches or your inside living height when you add a loft.  If floor to ceiling is 6 1/2 feet (78 inches) then your loft is  going to be somewhere between 30 and 58  inches high.  A 36 inch loft will force you to notice differences in pitched, rounded and vaulted ceiling designs.
Increase living space with pull outs in your tiny house – A DIY tiny house pull out is not recommended for the novice tiny house designer.  It takes a great amount of engineering research and consideration.  A pull out will expand your living space with little or no loss to existing space.  Here are a few considerations when you create your design:
  • Support of the extended or retracted pull out is needed for long term weight distribution while parked or traveling.
  • Weather seals need to withstand long term exposure to elements while parked or traveling
  • Locking pull out extensions for travel is needed.  Take into account everyday g-force stresses associated with common driving with a load (see minimums in the diagram below)
Forward acting forces Backward acting forces Sideways acting forces
0.8 g 0.5 g 0.5 g

What choices you make affect your final measurements – Some things may take less time to install, come free or cheap only to  consume precious space needed inside your tiny house.  Here are some things to monitor carefully or avoid completely:

  • Cedar siding can reduce your living space by 6 inches or more.
  • Using sheet rock or wood interior siding
  • Roof eves, gutters or downspouts or shutters designed for traditional houses
  • Secondary insulation needed to repair initial improper insulation methods
NOTE: Plan for travel – Beware of anything outside the edge of your width, height or length limits – Rolled up canopies, awnings, snap on emergency lighting or decorations can cause you to exceed the legal limits in a state.  Excess of one inch in any direction can cost you greatly in tickets, repairs or your life.  Travel tips that could affect your design
  • Some bridges marked XX feet xx inches could be inches less
  • Pay attention to overpasses-bridges and street signs – No trucks = less then 13.6 feet
  • Height or clearance markings measure from the lowest point in a ROAD, the shoulder clearance could be less