Locate the straw that you want to use for thatching. Choose straw that was sowed in the winter, because it is longer and stronger. Harvest the straw before it becomes ripe, as ripe straw breaks easier than unripe straw. Ask the supplier to allow freshly cut straw to dry for two weeks before you pick it up.
Lay the straw out before you use it and sprinkle it with water so it softens slightly. Gather the straw into bundles that are as big as you can fit in both hands -- about 5 inches wide and 18 inches around.
Tie each bundle tightly together and bring it up onto the roof. Attach the bundles to the roof beams with string so they are accessible when you need them.
Secure the straw in position using long, metal thatching hooks, called crooks, by hammering them into a beam. Start at the eave of the house and work your way across, laying each bundle tightly next to the previous.
Pound a nail into the end of each beam so 1 inch of the end sticks out. Wrap a piece of strong, galvanized wire around the nail. Stretch the nail across the row of straw bundles and wrap it around the nail on the other end. Tighten it as you wrap it. Trim excess wire with wire clippers.
Continue laying rows of thatch in this manner with each row overlapping by at least 3 feet. Wire the rows in place and pound crooks into the beams to secure them.
Create tight rolls with long, thick pieces of straw and wedge them into the sides of the roof frame to stop any drafts. Secure them in place with wire and crooks. Do the same on either side of the roof's peak.
Stuff any holes with loose straw or small straw bundles and wire them in place.
Groom your thatched roof according to your plans. You can cut the ends of the thatch flush using hedge trimmers and a piece of wood as a guide or you can leave the straw natural or taper the ends for a softer look.
Lay netting over the roof and secure it to the beams along the side with nails and hooks. The nets keep animals away and protect the roof from wind.