Hi, Rhiannon,
According to this site:
http://www.thatchco.com/thatchpg/faq.htm
"Thatch weighs only 7 pounds per square foot".
If anyone out there (are you there, Mr Gray?) wants to do the maths as to what the amount required would be to roof the structure, jump onboard........ If nothing else, it's an intriguing "take" on Stonehenge. :-)
Peace
Pilgrim
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