Don Vandervort, Head Homeboy, has written more than 30 DIY home improvement books, been a segment host on HGTV, served as MSN.com's home improvement expert and written countless magazine articles.
Whether an open-style roof is made of thin latticework or substantial beams, construction techniques are similar. Some can even be built apart from the structure and then installed.
Lath, Battens & Boards Whether you are using lath, battens, boards, or larger lumber, the width of the pieces and the spacing between them will determine the effect created by your overhead.
Creating shade. Wood thickness and spacing can vary greatly—as can the amount of shade the variations create. For example, 3/8-inch lath laid flat and spaced 3 inches apart will not cast much shadow. But 2 by 2s spaced half an inch apart—or 1 by 3s on edge—will cast considerable shade.
Here are some spacing guidelines used by landscape architects: Space lath that is up to 1/2 inch thick 3/8 to 3/4 inch apart. For stock that is 1/2 to 1 1/8 inches thick, make the spacing between 3/4 and 1 inch. You can space 2 by 2s up to 2 inches apart under certain circumstances, but spacing them 1 to 1 1/2 inches will make the patio more comfortable in most cases.
The direction to run the roofing material depends on the time of day you want maximum shade. If you want the greatest relief from sun at noon, run the material east to west; if you want shade in the early morning and late afternoon, run it north to south.
It's a good idea to test your roofing material by temporarily nailing a small amount of it at various spacing intervals to the rafters so you can study the effects of each configuration at different times of the day. Keep in mind that the angle of the sun changes from season to season, not just during the course of a day.
Roof height will also affect the degree of light that falls on your patio or deck. The higher the roof, the more diffused the light becomes. The lower the roof, the sharper the shadows it will cast on the ground.
Suitable spans. To prevent lattice-style roofing from sagging and warping, be conservative about the distances it spans. Do not span lath and batten more than 2 feet apart. You can span 1-bys up to 3 feet apart, but 2 feet is better; with 1-by-2-inch stock laid on edge—or with 2 by 2s—you can span 4 feet without objectionable sagging, but the boards may warp or curve a bit. Do not span any material more than 4 feet.
Sight down lumber to check for any crown (a curve along the edge); if the material has a crown, always face the convex side upward.
Nailing. Before nailing any boards, double-check that they are spaced evenly and aligned perfectly. Set aside pieces that are overly twisted or bent. To keep the spacing consistent between closely spaced lattice or boards, cut a scrap of lumber to use as a spacer.
Always use galvanized or other corrosion-resistant nails to secure the wood to the framework. With 3/8- or 1/2-inch-thick lath, use 3d or 4d common or box nails. For use on 1-inch stock, choose 8d nails. Use 12d or 16d nails for thicker materials. Nail twice at each rafter, and join cut ends directly over the rafters. If your wood tends to split, drill pilot holes before nailing.
Preassembly. To reduce your time on the rooftop, preassemble panels and fasten them as shown in the illustration above. You can make the panels practically any size, but 3 by 6 feet is the optimum dimension for lightweight material. Be sure the structural framing is true enough to receive the panels without a struggle. Patio Roofs & Gazebos All you need to know about building outdoor structures, from an inspirational gallery for unique ways to extend your living space outdoors, to step-by-step photo sequences to build an outdoor structure precisely suited to your needs.
It's a good idea to test your roofing material by temporarily nailing a small amount of it at various spacing intervals to the rafters so you can study the effects of each configuration at different times of the day. 