Loft Floor Framing and Sheathing

Marc Bilodeau/ Building, Tiny House

With the main floor complete, the next major step in construction is framing and sheathing the loft floor and roof. This step completes the rough framing and pave the way to the individual systems such as plumbing, propane, and electricity.

The loft floor in this tiny house on wheels consists of a sleeping area, closets, and storage loft.

The original loft floor plan
The original loft floor plan

Although there are changes to this floor plan, the layout of the sleeping area and storage loft remain the same.

Scope of Work

[more photos of this process]

Like the subfloor and main floor framing and sheathing, breaking down the job into smaller tasks insures each step is completed properly and accurately. The steps for this phase of construction are as follows:

  • Build and raise the walls in sections
  • Adding the Storage Loft
  • Framing the loft floor windows
  • Framing the roof, twice!
  • Sheathing the outside and roof
  • Celebrate!

Build and raise the walls

The primary concern with the loft floor and roof is to make sure it doesn’t exceed the height restrictions when traveling on roads and highways. The height from the ground to the roof tip measures 13′ 4″ (~ 4.06 Meters) which is under the typical height limit of 13′ 6″ (~ 4.11 Meters).

Framing the loft floor and roof
The quick summary of framing and sheathing the loft floor and roof from start to finish.

The walls of the loft were built in sections and the roof framing was added as the wall sections were raised. We started from the sleeping loft and worked our way to the storage loft.

Adding the Storage Loft

This tiny house includes a 2′ (~ 61 cm) wide storage loft above the entrance. The roof slopes steeper over the loft for the purpose of outside aesthetics.

Phases of constructing the storage loft
Phases of constructing the storage loft. (top) shows the floor framing (bottom) shows the floor and roof

The storage loft floor framing uses three 2″ x 4″ (38 mm x  89 mm) support joists. One of the support joists attaches to the wall frame. The other two support the storage loft floor. The supporting joists attach directly to the first floor loft frame which provides additional stability to the tiny house. They are attached to the first floor walls using 3″ (~ 76 mm) deck screws.

Framing the loft floor windows

Due to the limited height of the loft, the windows can be no more then 18″ (~ 46 mm) in height. Three 16″ x 32″ (~ 41 mm x  ~ 82 mm) windows will be installed in the loft floor. One in the sleeping area, and one on each side in the great room area.

Framing Loft Windows
(upper row) [left] areas where windows will be installed [middle and right] loft window framing without and with sheathing. (bottom row) [left] frame of an upper window in the great room [middle] loft skylight framing before cut out [right] loft skylight framing after cut out

Typical designs similar to this tiny house have two windows side by side in the loft. However, the intention is to build closets and shelf spacing in the loft area. Therefore, two windows will not fit side by side. Instead, a skylight will be installed above the mattress for night time stargazing and serve as a second egress in case of an emergency.

All rough framing for both the first floor and loft floor are 2″ x 4″ (38 mm x  89 mm) studs. The roof is 2″ x 6″ (38 mm x ~ 152 mm) studs for the rafters and ridge board.

Framing the roof, twice!

The skylight requires a 3:12 minimal pitch to effectively drain water around it during a rainstorm. After some math, I calculated the maximum wall height of 2 feet (~ 61 cm) and roof height of 3 feet (~ 91 cm). Wanting to maximize headroom in the loft, the roof beams extended from the roof and attached on top of the loft wall using hurricane ties.

The roof beams sit on top of the loft frame to maximize loft head room
The roof rafters sit on top of the loft frame to maximize loft head room

Since the progress of the roof was going well, I read the documentation for the skylight to order it for installation. That is when I discovered the actual angle for a roof of 3:12 pitch, which is 15 degrees. The tiny house roof is 12 degrees. Oops.

So, what went wrong? I began to search the web concerning roof framing and discovered the culprit after several pictures and diagrams. The roof rafters must be notched (also known as a birdsmouth notch) where they attach to the loft frame. This means the roof rafters must be replaced. The existing rafters are unusable since the angle and length change. It is better to find out at this point instead of completely finishing the roof.

The roof rafters are now correct, and the angle is 15 degrees for the skylight.

the correct and complete roof framing
Roof rafter framing with birdsmouth notch and the correct angle of 15 degrees

Despite the miscalculation on framing the roof rafters, the overall construction went well and I’m happy with how it came together.

Sheathing the outside and roof

The ZIP System panels come in different sizes. This tiny house has 5/8″ panels (~ 16 mm) on the roof, and 7/16″ (~ 11 mm) panels on the walls. Typically the thicker panels are for the roof, while the thinner panels are for the walls. However, the system allows for use of any thickness for either wall or roof.

TinyHome.io Loft and Roof framing and sheathing

Zip System Flashing Tape covers the areas where the panels come together. I found the ZIP System in general is easy to use and installs quickly. It certainly saved time and materials for this tiny house on wheels.

Celebrate!

After 38 hours of work between two people, the loft floor, roof framing, and sheathing are complete. With each milestone make sure to take the time to reflect and celebrate the work and treat any friends and family for their efforts.

[more photos of this process]