Unraveling The Tiny House Roof

Each day brings new tiny house fans. Just when you think there is nothing left to talk about you realize that a new crop of “NOOBS” to the tiny house world, shows up. The same questions – or seemingly the same questions – get asked and discussion ensues. What type of heater should I have? How do I know which trailer to buy? Is there a siding that is better than the other? Do composting toilets stink? 

courtesy of John Riebli

Recently though I have found myself reviewing the roof types of tiny houses try to challenge my design ideas on what makes a better mobile unit, which space gives more headroom, and which may work best for a treehouse.

There is a reason for every roof shape in a build. The roof is perhaps the most impactful part of the overall design. It is important to note then that there are six basic roof shapes including: Gable, Gambrel, Flat, Hipped, Mansard, and Shed (sometimes called a “French Roof”). It is worth saying that there are advantages and disadvantages to every roof shape. The final choice should be made according to what fits the appearance of the tiny house best. The following three are what I see most when touring tiny house builders spaces and festival events.

GABLE

The gable roof design is what we have all drawn since childhood when envisioning a house with mommy and daddy. It is sometimes referred to as an ‘A-frame’ roof and is measured in pitch in regard to the two planes. To find the size you would multiply length (A) x width (B) to get the square footage for each plane, then add the two planes together to derive the total square footage of the roof. For example:

Plane 1: 12′ x 10′ = 120 sq. ft.
Plane 2: 12′ x 10′ = 120 sq. ft.
Plane 1 + Plane 2 = 240 sq. ft. for the total square footage of the roof.

To further explain the gable roof, the pitch of said roof is its vertical rise divided by its horizontal span (or “run”), what is called “slope” in geometry, or the tangent function in trigonometry. The rise is typically first and the run second. In the USA, the run is denominated by the number 12, giving a ratio of how many inches of rise or fall there are to each 12 inches (one foot) of run.

courtesy of Wikipedia

GAMBREL

The gambrel roof is known throughout the United States as a “barn roof”. It is usually symmetrical in design with two-sides – a slope – on each side. (Historically this style of roof was known as a “Dutch roof.”) The upper slope is positioned at a shallow angle, while the lower slope is steep. This design provides the advantages of a sloped roof while maximizing headroom inside the building’s upper level and shortening what would otherwise be a tall roof. The obvious disadvantage is that this style roof is harder to build (more angles) and typically weighs more.

SHED

Shed roofs use single slope roofs. Depending on their height, they can be the perfect way to increase headroom in your tiny house. They are also (and arguably) the easiest roof to build as they have few angles. This type of roof only slopes down in one direction and involves one wall being built taller than the opposite one to create the pitch. It allows good drainage and while not the most aerodynamic from front to back, makes mounting on top of the roof (solar panels, TV antennas, etc) easy.