Thatched palm roofs can last over ten years before needing repairs when properly maintained. Durable, "green" and waterproof, they provide a tropical feel to any outdoor building. They are widely used in outdoor bars and gazebos. Sitting under a thatched palm roof on a hot summer day will keep you cool and out of the sun's harmful ultraviolet rays. The best palm fronds to use to construct your thatched palm roof come from the aptly-named thatch palm. Fronds from the cabbage palm and huano palm also work well. An 8 foot-by-4 foot roof requires 300 to 400 palm fronds. If your roof is larger, collect more fronds.
Split the fronds down the spines. Start on the large end using a large knife. Pound a metal pole into the ground and use that as an aid to split the frond down the entire length of the spine. Make two piles of fronds -- one for the right-sided fronds and one for the left-sided fronds.
Tie right-sided fronds to the roof structure using natural-coloured rope or twine. Starting at the bottom, progress all the way around the structure with the spines running horizontally. Place them in groups of two with the spines along each others' side. The fronds need to be installed correct side up. (The correct "up" side is the side that faces up naturally when the frond is on the palm tree.) The leaves of the fronds will hang off the edge of the roof and face diagonal down and right. Tie them down to your structure every few feet.
Install the fronds for the next row. Use the left sided fronds and install them in the same manner as Step 2. The leaves should be facing diagonal down and left.
Continue alternating right sided and left sided fronds until you complete the entire roof. When looking at your roof from the inside, you should only see the spines of the palm fronds.
For the roof cap, lay down several woven mats, and tie them down to the structure over the palm fronds.
Trim the fronds around the roof line to make a tidier look. You'll want several feet of overhang if possible, though.