How to Build a Tiny House – Part 7: Building the Roof

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How to Build a Tiny House – Part 7:
Building the Roof

It’s time to build the roof of your tiny house! Follow these simple, illustrated instructions.

October 2014

By the Editors of Skills Institute Press

Good things do come in small packages. Just ask internationally recognized small living expert, Jay Shafer. Ranging in size from 100 to 120 square feet, Jay Shafer’s DIY Book of Backyard Sheds & Tiny Houses (Skills Institute Press LLC, 2013) features beautiful small houses can be used as guest cottages, art or writing studios, home offices, craft workshops, vacation retreats or a full-time residence. Whatever your building goal, this book will teach you how to plan and build your structure from the ground up. The following excerpts from chapter four, “How to Build a Tiny House,” walks you through building the roof of your tiny house.

You can purchase this book from the GRIT store: Jay Shafer’s DIY Book of Backyard Sheds & Tiny Houses.

Looking for other steps? Check them out in How to Build a Tiny House.

Erecting Sloping Roofs

For small-scale post-and-beam structures, roof rafters can be measured and marked in position. Lumber sizes given in this section are guidelines; consult the building code in your area for possible variations. For an open roof, buy pressure-treated wood for all the parts.

A Shed Roof

This type of roof is defined as one that slopes because one side of the structure is built higher than the other. To calculate how much higher, start with the desired roof pitch, which in the example below is 1-in-12 (or 1 inch of rise for every foot of roof width). In this method, the 2-by-6 rafters butt against the crossbeam on the high side, but one-half their width (2 5/8 inches) fits into notches cut in the lower crossbeam. You will need to add this amount to the high side, or subtract it from the low side, when building the sides.

A Gable Roof

In this type of roof, the rafters rest on beams and meet at a 1-by-8 ridge beam, which forms the peak of the roof. This type of roof is easier to lay out than the shed because the sides are built at the same height. A simple marking guide will enable you to mark the rafters accurately with no calculation or guesswork.

Bracing With Collar Ties

Both types of roof suffer an inherent weakness. Since the rafters meet the beams at an angle, their weight and the loads they bear tend to push the sides outward. This can be overcome with collar ties. Brace a shed roof by attaching 2-by-6 collar ties to each pair of end posts, as shown below, with 3/8-by-3 1/2 inch lag screws. For gable roofs, which are more prone to spreading, join every third pair of rafters with a collar tie.


A Shed Roof

1. Marking the Rafters

Make rafter marks 16 inches on center on the crossbeams.

Snap a chalk line down the middle of a rafter board. With a helper, align the board so its top is flush with the top of the upper crossbeam and the chalk line touches the top edge of the lower crossbeam.

Tack the rafter to the upper crossbeam, and outline the edges of the lower crossbeam for a bird’s-mouth cut, a notch that fits the rafter snugly to the crossbeam.

Mark along the inner face of the upper crossbeam for the ridge cut, that fits the rafter to the upper crossbeam. With a level, mark a vertical overhang cut on the end of the rafter.


2. Cutting and Installing the Rafters

Support the rafter on a pair of saw horses and cut along the marked lines with a hand saw (left) or a saber saw.

Mark out the remaining rafters, using the cut rafter as a template.

To raise the rafters, toenail them with 3 1/2-inch galvanized common nails to the upper and lower crossbeam at the marked spots.

For additional support, secure each rafter to the lower beam with a multipurpose framing anchor (inset) with the nails recommended by the manufacturer.

A Gable Roof

1. Marking Rafters for a Gable Roof

Construct a marking guide by attaching a 1-by-8 upright to the center of a 2-by-6 plank long enough to span the structure. Secure the upright at 90 degrees to the plank with a 1-by-2 brace. Mark the desired height of the peak on the upright.

Set the marking guide on the crossbeams, 1 1/2 inches in from the edge, with the upright centered between the sides. Tack the guide in place.

Check that the upright is plumb and adjust the brace as needed. Snap a chalk line at the center of a rafter board and position the board against the guide as shown (right).

Mark the bird’s-mouth cut, the ridge cut, and, with a level, the overhang cut (above). Remove the marking guide. Cut the bird’s-mouth, ridge, and overhang, then mark and cut the other rafters using the first one as a template.


2. Assembling the Frame

Cut a 1-by-8 ridge beam to the same length as the crossbeams and mark it for rafters every 16 inches.

On one side of the beam, fasten a rafter to each end, nailing through the beam into the end of the rafter with three 3-inch galvanized common nails.

Toenail rafters to the opposite side of the beam (below).


3. Positioning the Frame

Brace the end rafters temporarily with 1-by-4s nailed across them.

With three helpers, lift the frame into place, setting the bird’s-mouth cuts onto the crossbeams.

If necessary, remove the temporary bracing so you can adjust the fit of the rafters, and replace it when they are correctly positioned.

Toenail the rafters to the crossbeam with 35-inch common nails.

To strengthen the rafter-and-beam joints, add framing anchors with the nails suggested by the manufacturer.

4. Fitting the Collar Ties

Set a 2-by-6 equal to the width of the structure atop the crossbeams and against a pair of end rafters, and mark it along the top of the rafters.

Cut the board at the marks and use it as a template for the other collar ties.

Nail the collar ties to the end rafters with six 3-inch common nails.

Mount the rest of the rafters, nailing a precut collar beam to every third pair of rafters as you go; then remove the temporary bracing.

For further instructions, see How to Build a Tiny House.

Reprinted with permission from Jay Schafer’s DIY Book of Backyard Sheds & Tiny Houses: Build Your Own Guest Cottage, Writing Studio, Home Office, Craft Workshop, or Personal Retreat by Jay Schafer and published by Skills Institute Press LLC and Four Lights Tiny House Company, 2013.Buy this book from our store: Jay Shafer’s DIY Book of Backyard Sheds & Tiny Houses.

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