How to Post Frame Construction

Post and frame construction leaves flexible, open spaces.

Post frame construction refers to a building design in which the structure is supported by posts sunk into the ground or mounted on a concrete slab. Wood framing is used to build the walls between the posts and to construct the roof which is supported by the posts. Lateral strength against wind loads is provided by the cladding on the walls. Post frame construction is popular because it is very flexible and the designs are simple.

Things You'll Need

• Posts
• Beams or lumber for roof trusses
• Framing lumber
• Hardware for connecting the posts and roof trusses
• Siding for walls
• Sheathing for the roof

Instructions

1. Place posts of adequate dimensions to support the roof loading around the edge of the building. Posts are usually placed on concrete pads in holes reaching below the frost line. Pads must be designed to support the projected loads. Posts can also be mounted on grade level concrete pads, if extra-thick support pads have been poured where the posts are to be mounted. Posts are generally solid-sawn or laminated wood columns sized to support the weight of the roof structure and projected snow loads.

2. Mount the roof trusses. Post and frame roof trusses are beams or framed lumber structures which are attached to the tops of the posts to span the interior space. Special fittings are used to connect the roof trusses to the posts. Ideally the roof trusses will rest on top of the posts and be bolted into place with the connecting hardware. For smaller buildings, trusses are sometimes attached to the sides of the posts and the fittings may be self-fastening or be screwed or nailed into place.

3. Fill in the walls and roof structure with framing lumber. Mount horizontal framing lumber across the posts to make up the walls and across the roof trusses to form the roof. Construct the roof overhangs and eaves. The framing lumber must be of adequate strength to support the wall and roof cladding. Its strength and the way it is fastened to the posts and trusses must also be adequate to transfer lateral loads from the cladding to the posts and trusses.

4. Mount the siding on the framing lumber of the walls and the sheathing on the roof following the manufacturer's instructions. For industrial and commercial buildings, metal siding and roofing is often used for post and frame construction. If the roof is going to be insulated, make adequate provisions for roof ventilation. The interior can now be finished with great flexibility and configured to suit the building's purpose.

References

• NFBA: Post Frame Construction Guide
• American Wood Council: Design for Code Acceptance, Post Frame Buildings