Phragmites australis is known as "water reed", "common reed" or "Norfolk Reed". Knowing these alternate names is important when looking for information about the thatching craft.
In the UK, thatching is described as a growing business with the number of thatchers having increased from about 200 to about 1500 over the past 45 years (see here near the bottom of the page).
In the the Wikipedia entry for phragmites, uses are covered in section 4 including phytoremediation water treatment. Additional uses are as a craft material (for basket and mat making, paper, musical instruments), fences, cattle pens, fishing poles, spears, food (both human and animal) and bee keeping.
The Purdue Crop Index on phragmites gives additional uses for cattle grazing, as feedstock for rayon and board making, "a fine fibrous material suitable as a filler in upholstery", rope making, partitions and brooms. Food and folk medicine uses are also described.
Use of chopped, freshly harvested phragmites for biogas production with the by-product (sludge) spread on farmland in Sweden is described in this book.
Phragmites is harvested and sold commercially in China, presumably for roofing.
When you have lemons, make lemonade!
Thank you for your interest.
Lion's Head, Ontario, Canada
I have not seen any of the ultra tall variety yet.