You can, or could, buy Tyvek groundsheets from Bob at Backpacking Light. I have two of different sizes. They are excellent as a footprint if you want one. They did not need washing or scrunching up to make them useable. They do get softer and more pliable with use. But they are NOT completely waterproof and I would not, therefore, rely on Tyvek as a groundsheet in Scotland in May.

Thanks David,i got one when i got my scarp 1 in 2009/10 ish but never used it.It's been hiding in my garage forgotten about ever since and it never got used.
I have just purchased a duomid and was toying with the idea of trying the tyvek out, just wanted some views on it.

Cheers.

Yes, I've used Tyvek up until now.

Used a sheet direct from the builder's yard and it's tough stuff. Not noisy and easy to clean and waterproof.

Also bought a sheet from Backpacking light, bit crinkly, but you can peg it out and is water resistant enough.

Now bought a tub from Oookworks.