How to Build a Tiny House – Part 4: Building the Frame

Explore framing options and learn the essential steps toward framing your tiny house.

August 2014

By the Editors of Skills Institute Press

Backyard Sheds and Tiny Houses Book Cover

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 choosing and building a frame for 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.

Gazebo

The gazebo is an open post-and-beam structure, usually with five, six, or eight sides and a peaked roof. The version shown here is six-sided, and can be built up to 12 feet in diameter—a larger gazebo requires collar ties to connect opposing rafters; the collar ties are fastened to the bottom end of the rafters.  A gazebo can be left open or covered with woven reed or bamboo, with fiberglass or aluminum screening, or with lattice.

A gazebo’s foundation can often be as simple as concrete blocks or 6-by-6 wooden blocks set under the corner of the platform. If the site is uneven, embed the blocks in the earth. Before beginning, always check local building codes; some may require a more substantial footing.

 

 Gazebo Frame

Anatomy of a Hexagonal Gazebo

Six 4-by-4 posts toenailed to a wood platform and secured to the beam-and-rafter unit that forms the roof provide the uprights of this post-and-beam structure. The gazebo platform consists of perimeter boards, joists, and decking— all made from 2-by-6s. Six crossbeams, five handrails (all 2-by-4s), and six plywood arches give the structure lateral rigidity. The 2-by-6 roof rafters are nailed at their bases to the crossbeams and attached at their peaks to 2-by-4 spacers. The entire structure rests on concrete blocks. 

 Illustration of Gazebo Frame Anatomy of a Hexagonal Gazebo

Six 4-by-4 posts toenailed to a wood platform and secured to the beam-and-rafter unit that forms the roof provide the uprights of this post-and-beam structure. The gazebo platform consists of perimeter boards, joists, and decking— all made from 2-by-6s. Six crossbeams, five handrails (all 2-by-4s), and six plywood arches give the structure lateral rigidity. The 2-by-6 roof rafters are nailed at their bases to the crossbeams and attached at their peaks to 2-by-4 spacers. The entire structure rests on concrete blocks.

Cutting Parts for Different Shaped Gazebos

Post-and-Beam: A Classic Method Revived

Post-and-beam structures are an elegant complement to outdoor living. Built with pressure-treated wood and left without sheathing, the post-and beam framework can be used as an arbor or a trellis; roofed and sheathed with openwork materials, it becomes a garden shelter. With weatherproof siding and roofing, the structure can be a workshop, shed, or studio.

Foundations

For an open-roofed structure, a simple concrete slab or set of precast concrete piers is adequate foundation (page 86). A closed-roofed structure, particularly one that must bear the weight of snow, requires a turned-down slab or concrete piers with footings set below the frost line. The latter is similar to the footings for the brick wall except the blocks are built at each post location rather than along the whole outline.

The Posts and Beams

The size of the posts for an unroofed structure is determined by the building’s width. Long, narrow structures are easier to build; if the width is less than 8 feet, 4-by-4 redwood or pressure-treated posts suffice. If the structure is wider than 8 feet but less than 12 feet, use 4-by-6 posts. Determining the size of posts for a roofed post-and-beam structure requires more precise calculations and varies from area to area. Consult your local building code.

The size of the beams is determined by the span between posts. The width in inches of a 4-inch beam should equal its span in feet. Thus, a 4-by-6 beam can span distances up to 6 feet, a 4-by- 8 up to 8 feet, and so on.

 Rafter Sizes for Open Roof Choosing Rafters 

Rafters to bridge the beams can be spaced as far apart as 48 inches in an unroofed structure; use the table at right to determine the spacing and lengths of rafters for an open roof. If you plan to roof the structure, the rafters should be set no more than 16 inches apart. Use 2-by-4s for a structure up to 5 feet wide, 2-by-6s for up to 9 feet, 2-by-8s for up to 11 feet, and 2-by-10s for up to 14 feet.

Anatomy of a Post-and-Beam Structure

Metal connectors hold together the basic post-and-beam framework. The posts are attached to post anchors fastened to a concrete slab (right) or to precast concrete piers (Masonry Foundation Piers for Stronger Supports). At the tops of the posts, metal post caps secure the beams. Rafters are attached to beams with metal framing anchors. The beam ends overhang the posts below them, and the rafters overhang the beams. Diagonal 2-by-4 cross braces are attached with lag screws.

 Post and Beam Illustration
 

Erecting Posts

1. Setting the Post Anchors.

The U-shaped anchors are bolted to the concrete slab with an offset washer that permits post positions to be shifted slightly for alignment.

Snap chalk lines 2 inches in from each side of the slab.

Place anchors and washers at each post position and mark the location for the lead shield.

Drill a 3/4-inch hole 4 inches deep at each mark with a masonry bit. Drop a 3/4-inch lead shield into the hole.

Place the post anchor and washer over the hole, then tighten a 1/2-inch lag screw into the shield until it is snug but the anchor can still be shifted. 

 Illustration of Post and Beam

Set a post support inside each anchor.

 Post and Beam  Assembly Illustration 2. Raising the Posts.

Install post caps on the top end of the posts with 3 1/2-inch framing-anchor nails. Place a post onto the post anchor.

Have a helper hold the post plumb, checking with a carpenter’s level on two adjacent sides. Secure the bottom of the post to the anchor (left).

Align the outside post edges with the building lines and tighten the lag screw (inset). Repeat for all the other posts.

 

3. Plumbing and Bracing the Corners.

While a helper holds the corner post plumb—checking with a level—brace the post with 2-by-4s nailed to stakes and to the post at least 20 inches from the top.

Repeat for each corner.

 

 Post and Beam Illustration
 Illustration of Post and Beam Frame

Raising Beams

1. Attaching the Beams.

Mark the tops of the beams for rafters, spacing them as desired; refer to the table on page 88 for maximum spacings and spans. Make the first mark to position the outside edge of an end rafter flush with the outside edge of a corner post.

Set each beam in the post caps atop a row of posts, marked-side up, aligning the outermost marks with the outside edges of the corner posts.

Have a helper hold the beam steady while you nail the corner post-cap flanges to the beam with 3 1/2-inch nails designed for connectors.

Plumb the intermediate posts with a level, then nail them to the post-cap flanges (above).

 Alternative Ways to Attach Post to Beam
  2. Putting Up Rafters.

Measure and cut the rafters following the table on page 88, adding 24 inches to the total length to give a 1/2-inch overhang on each side.

Nail a framing anchor to the top of one beam on one side of an end-rafter mark with 2 1/2-inch connector nails.

Nail another anchor on the top of the opposite beam, on one side of the mark.

Make a mark on the side of a rafter 12 inches in from each end, set the rafter against the anchors, and nail it in place with 1 1/2-inch nails (left).

Attach the remaining rafters the same way.

 

3. Mounting the Braces.

The 2-by-4 braces can be cut ahead of time. For most applications cut them at a 45-degree angle at each end and 26 inches in length along their longest edge.

Tack the braces in position so one end is flush with the top of the beam and the other is aligned with the center line of the post. (For the end post align the lower end of the brace with the outside edge of the post.)

Drill a 5-inch-diameter pilot hole through the brace and into the beam or post. Secure the braces with 3/8-by-3-inch lag screws and washers, driving the screws in with a socket wrench.

Attach the end braces similarly, but position the higher end flush with the top of the rafter, as shown on page 90. This will mean cutting longer pieces than the standard cross braces.

Remove the temporary nails and bracing.

 

The A-Frame: A Tent Build With Plywood

A Frame Illustration 

One of the simplest of all buildings takes the form of a braced triangle—an A-frame—rising from the ground. The rafters serve as both roof and walls and enclose a structure that is practical for many types of small outdoor buildings. A low A-frame, with a peak 3 to 5 feet above the ground, might be used as a pet shelter or a storage shed; a higher one, with 6 or more feet of headroom, can serve as a garden house, playroom, or studio.

Rafter Length

In every A-frame, the walls that form the roof are of equal length, but the angle at the peak may vary considerably, affecting both headroom and floor space. A typical A-frame, like the one on these pages, is an equilateral triangle, with a base and sides of the same length. A-frames with steeper sides have more headroom, but proportionately less floor space; flattening the triangle has the opposite effect.

Planning the Foundation 

As long as the A-frame is kept relatively small—less than 12 feet high— it does not need a full foundation extending below the frost line. It can rest on a concrete slab (above) or on concrete piers (Masonry Foundation Piers for Stronger Supports). Smaller buildings can rest directly on level ground or on a bed of gravel. Like the rafters of a roof truss, the A-frame rafters will tend to spread unless they are tied together. One way to secure them is by fastening floor joists to the rafters. This works well for a playhouse or a garden shed. Another method is to bolt the sole plates to the slab.

Anatomy of an A-Frame

The rafters of this typical A-frame are 2-by-6s joined at their peaks with triangular plywood gussets. (The gussets on the outermost side of the doubled end rafters are omitted so the sheathing will lie flat against the vertical walls.) Multipurpose framing anchors connect the base of each rafter to the 2-by- 8 sole plates bolted to the concrete slab. The end walls are framed with conventional 2-by-4 sole plates and studding, and the entire structure is covered with plywood sheathing and a weatherproof covering.

A Versatile Structure

 

Large outbuildings like the one shown below can serve as garages, storage areas, studios, workshops, or some combination of all of these. Almost any purpose can be accommodated, even living quarters. Each use, however, has requirements that should be considered early in the planning process.

A garage needs a driveway, walkways, a main entrance, and perhaps a side door. The floor must be sloped for drainage. For garden storage, include a door that provides easy access to the garden. A studio or shop should have windows, and possibly a loft for storage. If you need electricity and water, consult your local utility companies about preparing the structure for their installation.

Planning the Construction

Draw a floor plan of the building on a map of your property to ensure it is located at least as far from the house and the property lines as local codes require. Then sketch front and side views of the building on graph paper to determine whether the building will harmonize with the main house and surrounding property. You will probably need a building permit.

Bring along your diagrams and sketches, and be prepared to describe the type of foundation, wall construction, and roof design that you propose. Some localities require a soil test to determine whether it will support the proposed structure. And set up an inspection schedule well in advance so that work will not be delayed.

Anatomy of an Outbuilding

With the help of a few ingenious professional techniques, a turned-down slab eliminates the need for costly forms or uncommon masonry skills; stud walls can be built on the ground and erected as units; and prefabricated trusses, which require no tricky rafter cuts or a ridge beam, make the installation of a sloping roof a simple assembly process.

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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