Learn how to build an a frame house (complete with a cozy sleeping loft) in this illustrated, step-by-step guide.
One of the sturdiest of all structures is the A-frame, whose skeleton consists simply of a row of triangles. The A-frame roof is defined (and identifed) by its iconic triangular shape and steep roof pitch, forming the hallmark of the A-frame style. The bases of the triangles are the joists that support the floor, and the sides are the rafters that hold the combined walls and roof.
This simple but strong architectural house style is often featured in compact cottage house builds. The simplicity of construction and comparatively low cost make it a popular choice for vacation cabins or an off-grid home. Any style of foundation can serve as its base. Slab, pier, and crawlspace options all work well as foundations depending on local weather conditions and sourounding enviorments.
A-frames gained widespread popularity in the post-World War II era, especially in the 1950s and ’60s, when they became iconic as affordable second homes and ski cabins in North America. Their angled sides efficiently shed snow and rain, making them ideal for mountainous or heavily wooded environments. The steep rooflines and sloped roof make them particularly suited for colder climates and snowy climates, where snow load is a consideration.
While traditional A-frames use wood framing and asphalt shingles, modern variants may incorporate metal roofing, SIPs (structural insulated panels), and solar arrays for improved insulation and off-grid performance(Eco friendly options). Their energy efficiency and compact A-Frame floor plan make them a great choice for vacation home design or year-round living.
Pros of A-Frame Cabin Plans
Cost-Effective & Easy to Build
The simple structure uses fewer materials and is often quicker to construct–ideal for budget-conscious or DIY builders. Their straightforward construction and minimalistic design also reduce purchasing materials costs.
Excellent Snow & Rain Shedding
The steep pitch of the roof naturally sheds snow and rain, making it perfect for snowy or wet climates.
Strong Structural Integrity
The triangle design offers exceptional durability and wind resistance, ideal for remote or rugged locations. This durable architectural style is favored for vacation homes in exposed environments.
Loft-Friendly Layout
The vertical space accommodates lofts for sleeping or storage, adding usable square footage without increasing the footprint.
Planning Your A-Frame House
The most common shape is equilateral — joists and rafters are equal in length and set at angles of 60 degrees to each other. This creates the classic A-frame roof shape and is the basis for a typical plan. You can use different angles to modify the shape, however (see “Common Floor-to-Rafter Angles,” below).
An A-frame can be built to almost any size simply by varying the number of triangles and their dimensions, but a cabin with a sleeping loft must have rafters at least 20 feet long to allow adequate headroom on both floors. A-Frame floor plans are often customized to suit both compact and extended living needs, often including outdoor spaces like decks or porches for extended outdoor living.
For a small structure like the one described here, three people can lift the assembled triangles into place without the assistance of special equipment. A structure with rafters greater than 24 feet may prove too unwieldy for a crew of amateurs. Frame doors and windows in the end walls. For a large A-frame, plan a lot of windows. This enhances natural light in the living space and integrates well with designs emphasizing outdoor living.
A-Frame Tools
- Screwdriver
- Circular saw
- C-clamps
- Electric drill
- Hammer
- Carpenter’s level
- Carpenter’s square
- Plumb bob
- Wrench
- Saber saw
A-Frame Materials
- 1-by-2s, 2-by-4s
- 2-by-6s, 2-by-8s
- Pressure-treated 2-by-6s, 2-by-10s, 4-by-4s
- Exterior-grade plywood (3/4-inch)
- Wood glue
- Common nails (2-inch, 2 1/2-inch, 3 1/2-inch)
- Galvanized common nails (2 1/2-inch, 3-inch, 3 1/2-inch)
- Ring-shank nails (2 1/2-inch)
- Wood screws (1 3/4-inch No. 8)
- Roofing materials
- Carriage bolts (5/8-inch-by-6-inch; 1/2-inch-by-4-inch, 6-inch)
- Lag screws (1/2-inch-by-4-inch)
- Multipurpose and framing anchors and nails
- Wooden ladder
- Concrete mix
A comprehensive materials list like this is essential for accurately purchasing materials before beginning your build. The choice of materials, especially natural materials like pressure-treated wood and plywood, impacts both durability and energy efficiency.
Anatomy of an A-Frame House
This 20-foot-per-side equilateral A-frame rests on tripled 2-by-10 pressure-treated beams supported by masonry block piers. This structure reflects a typical A-Frame floor plan found in compact vacation homes. The triangles, spaced 24 inches apart, are formed of 2-by-8 rafters joined at the apexes with plywood gussets and sandwiched at the bottom by pairs of pressure-treated 2-by-6 joists. (A cabin larger than this structure would require correspondingly larger framing lumber.) At the end walls and under the sleeping loft, horizontal 2-by-6 collar beams are fastened between the rafters.
The rafters of the end walls are doubled to provide a flush nailing surface for the exterior sheathing. The sleeping loft, reached by a ladder, is framed by a railing secured to posts and rafters. Knee walls along the sides of the cabin provide concealed storage areas. The deck rests on 2-by-6 joists set 16 inches apart.
Posts for the railing are secured to the deck joists. The stairs are set on concrete footings and are attached to the deck with metal framing anchors. All exposed wood is pressure-treated lumber. An asphalt-shingle roof is shown.
Common Floor-to-Rafter Angles
(Rafter length, joist length, rafter/joist angle, rafter/rafter angle)
- 16 feet, 12 feet, 68 degrees, 22 degrees
- 16 feet, 14 feet, 64.1 degrees, 26 degrees
- 16 feet, 16 feet, 60 degrees, 30 degrees
- 20 feet, 12 feet, 72.5 degrees, 17.5 degrees
- 20 feet, 14 feet, 69.5 degrees, 20.5 degrees
- 20 feet, 16 feet, 66.4 degrees, 23.6 degrees
- 20 feet, 20 feet, 60 degrees, 30 degrees
These measurements are especially useful for customizing A-Frame construction plans to meet specific spatial needs or to create extra space under the roof.
Cutting A-Frame Joists and Rafters
- To cut the joists and rafters quickly, make a jig for each angle to be cut.
- Mark a scrap board at the angle of the joists or rafters and set it on a work surface.
- Place a 2-by-4 on each side of the board and fasten them down with screws.
- Align a 1-by-2 with the mark and screw it to the 2-by-4s as a cutting guide.
- Run a circular saw along the guide, cutting a kerf through all three boards.
- Remove the scrap board and replace it with a joist or rafter, marked to length.
- Align the mark with the kerf and cut the board.
- Cut the other end so both cuts angle toward the middle.
Assembling the A-Frame Triangles
- Clamp the ends of two joists around the base of a rafter, aligning the ends and edges of the boards, and drill a 5/8-inch hole through the three layers.
- Fasten the boards together with a 5/8-by 6-inch carriage bolt, washer and nut.
- Bolt the opposite ends of the joists to the base of another rafter in the same way.
- From 3/4-inch exterior-grade plywood, cut two triangular gussets to the same angle as the A-frame.
- Butt the top ends of the rafters together and fasten the gussets to each side of the seam with wood glue and 1 3/4-inch No. 8 wood screws.
- Add a second carriage bolt to each joist-rafter joint.
- Assemble the remaining triangles in the same way, but secure gussets to just one side of each end triangle.
- Allowing for at least 7 feet of headroom, mark both rafters of each triangle at the end walls and under the loft for collar beams. For each triangle, cut two collar beams to fit between the outside edges of the rafters, and then bolt them on as you did the joists.
- Cut 1-by-2 spacers to the joist width and fasten them with 2-inch common nails between all of the pairs of joists and collar beams at 2-foot intervals.
- Double the rafters of the end triangles: Cut four lengths of rafter lumber — two to fit between the joists and collar and two between the beams and rafter peaks — and nail them to the outsides of the rafters with 2 1/2-inch nails.
Erecting the A-Frame Triangles
- Mark the triangle locations on the beams at 2-foot intervals.
- Nail scabs — 1-foot-long 2-by-4s — to the insides of the outer beams on each side of the marks for the front end triangle.
- With a pair of helpers, lift and position the end triangle on the beam between the scabs.
- Plumb the triangle and brace it with two 2-by-4s nailed diagonally between the rafters and outer beams so the top of each brace is least 4 1/2 feet from the base of the rafters.
- Position and plumb the remaining triangles in the same way, bracing them with a 1-by-2 nailed to each side of the adjacent triangle.
- When all of the triangles have been braced, remove the scabs and attach the triangles to the beams, installing a multipurpose framing anchor to each side of every joist. In a high-wind area, use hurricane ties. Nail the bottom corners of the triangles to the beams.
- Sheathe the outside of the frame, laying decking for shakes, or 4-by-8 panels of 5/8-inch exterior-grade plywood for metal roofing or asphalt shingles. Work from bottom to top, fastening the sheathing with 2 1/2-inch common nails. Leave a 1/8-inch gap around panels and stagger the joints. Remove the bracing after you lay the bottom course of panels.
- Cover the floor with plywood.
Finishing Touches
If the A-frame includes a loft, provide it with stairs or a ladder and a sturdy railing. Rest a deck, if you build one, on the same foundation as the main structure and surround it with a railing. Buy deck stairs at a building center or construct them on site. Decks are key elements in outdoor living design and contribute to the total square footage of usable space in many A-frame plans. Install insulation between the floor joists, rafters and end wall studs as you build. High-quality roof insulation improves energy efficiency, particularly in colder climates.
Common Questions About A-Frame Cabin Plans
How much does it cost to build an A-frame cabin?
Basic DIY kits can start as low as $10,000-$20,000, while fully custom A-frame homes typically cost between $100 to $200 per square foot, depending on size, materials, and location. But by doing it yourself it can be much cheaper.
Can I build an A-frame cabin myself?
Yes, A-frames are popular for DIY builders. Their relatively straightforward design, especially with prefab kits, makes them beginner-friendly. However, experience in basic construction or hiring a contractor for critical tasks is recommended. Following detailed construction plans and a comprehensive materials list can help you stay organized.
Are A-frame cabins good for year-round living?
They can be, if properly insulated and built with quality materials. The roof can limit attic space and insulation depth, so using modern materials and energy-efficient windows is key for cold climates. This house style excels in weather conditions common in mountainous regions.
Do A-frame cabins require special foundations?
Not necessarily. Most A-frames can use traditional foundations like slab, pier, or crawlspace types. The best foundation depends on soil conditions, slope, and climate.
Reprinted with permission from Cabins & Cottages, published by Fox Chapel Publishing, 2011.
