Standard Framing Techniques
What is it:
Standard framing is what you typically see in wood framed structures across America. Wood studs (Douglas Fir standard), usually 2×4 but sometimes 2×6, are spaced 16″ on center so that sheet goods like plywood sheathing, OSB sheathing and drywall (which come in 4’x8′-12′ sheets standard) can be fastened to the structure on the perimeter, these are the walls ‘base studs’. If the spacing was any less or any more than 16″ on center this wouldn’t line up on the edges of your sheet goods and could lead to more cuts and compromising the integrity of the material (sheathing is structural and offers less structurally in small pieces). These studs are spaced on top of a ‘bottom plate’ which is how the wall is fastened at the bottom. There is a ‘double top plate’ which refers to the top portion of the wall consisting of two layers of studs which distribute the weight of the roof downward equally through the wall studs. Generally standard framing is fastened with 16 penny (aka 16-d) framing nails which are 3.5″ long.
It has most commonly been recommended to use sheathing (either OSB or Plywood) that is at least 7/16″ thick in order to offer your structure enough shear strength. There are alternatives to this such as additional strapping and T-111 siding.
Roof ‘rafters’ are generally 2×4 -2×8 lumber (Douglas Fir) placed 16″-24″ o.c. depending on dead and love loads to accommodate and length of span required as well as amount of insulation desired. Various roof styles require different size rafters.
After you have all of your studs spaced out at the appropriate distances you can start to add your door and opening (window) locations. Standard door and opening are framed like this:
Each opening has a ‘header’ which collects the weight that would otherwise be carried by the wall studs and distributes it downward through a trimmer and king stud. A ‘king stud’ is a full length stud and may or may not be one of the studs you’ve got spaced 16″ on center. A ‘trimmer stud’ directly fastens to the king stud but stops at the header which defines the rough opening height (generally 2″ taller than the height of the door being placed). For windows you have an additional ‘sill’ which defines the bottom of the rough opening for the window. The rough opening is generally 2″ bigger than the actual window being placed, dependent on the size of the window flanges on the window (you need enough room to level and plumb you window in case the opening is slightly out of square but not too much that you cannot fasten the window flanges on the entire perimeter). The sill is supported by cripples which are aligned with the base studs that are placed 16″ o.c.
Generally a corner condition where two walls come together in a standard framed home looks like this:
You’ll notice there is an extra stud that creates a nailing surface for the wall finish in the inside corner. The 16″ dimension would start from the outside corner of the structure to assure that you have a nailing surface every 4′ along the outside perimeter of the structure for your sheathing (which is structural)
This is very commonly known, there is a lot of information out there on standard framing. It is typically ‘over engineered’ for a tiny house and is safe so long as you follow the general rules.
There is more lumber used than in ‘advanced framing‘ which can lead to greater amounts of thermal bridging and more weight.
Tiny House Specific and Regional Considerations:
Standard framing is itself not enough when considering the forces a tiny house is exposed to while in transit, you will need to use additional strapping to secure your roof components as well as hurricane ties to tie your rafters to the walls. Additionally you will need to secure your walls solidly to your foundation using a minimum of 3/8″ lag bolts (recommended at 24″ o.c.). It is also recommended to add Simpson Hold-downs at the front corners.
Wall, roof and floor thicknesses may vary based on the amount and type of insulation desired. Typically they are 2×4 construction but in some cases more depth may be desired.
This is a collaborative site, if you have something to add/correct leave a comment! If you have some words of wisdom on any of the methods mentioned feel free to share in the comments!