A pergola is basically an arbor or trellis, which is a structure usually consisting of parallel colonnades supporting an open roof of girders and cross rafters. A pergola can be used to create shade, or as an architectural addition to your yard.
Most pergolas or arbors consist of at least 2 posts if attached to your house on one end, or 4 posts for a free standing pergola. Depending on size, the amount of posts used is limitless, and spacing is decided on size and length of the beams running between the posts. The beams running between the posts usually carry rafters. Rafters are one of the most important parts to creating shade.
For maximum shade, you will want to situate your pergola so the rafters are running parallel to the movement of the sun. Furthermore, you’ll want to use a tall enough rafter, spaced close enough together, to create shade whenever the sun isn’t directly overhead. The rafters are then topped off with battens. The battens are usually 2×2 or 2×4 material. The closer the spacing, the more sun will be blocked at the noon hour. The battens also act as in integral part in tying the whole structure together. Finally, a pergola can be capped with a variety of materials. Such as corrugated roofing, poly sheeting, etc, to create total shade, or to keep the rain out.
Pergolas can be constructed in a variety of materials including wood, aluminum, vinyl, steel, and composite material. Check out my post titled “How to Choose the Right Material for Your Pergola“.