Well, let’s talk about a tarp really. You will need about an ounce I guess for the smallest Polycro groundsheet (unless you don’t use one, because you are perhaps desert hiking). To that you have to add the weight of a fly. I calculated that I could make my Pocket Poncho Tent (which weighed 185 grams in the silpoly I used) in .32oz/yd2 cuben fibre, in which case it would weigh about 75 grams. It gives a reasonable shelter on at least three sides (which I think is desirable). There are some tarps out there available commercially which push close to that.
For example there is Mountain Laurel Designs ‘Grace’ Tarp in cuben at 140 grams for a roof which is 5’ at one end, 7’ at the other and 9’ long: https://mountainlaureldesigns.com/product/mld-grace-tarp/ It will set you back US$270 (Sept 2018)
Zpacks have the http://www.zpacks.com/shelter/hexamid_pocket.shtml again in .51 cuben fibre with a claimed weight of 96 grams. These weights are for the tarps alone without guys, stakes, etc. Its price is US199 (Sept 2018) which seems very reasonable for what it is.
A firm called Lightwave seem to make a couple of very light tarps. The Starlight 2 at a claimed weight of 96 grams (The site also says 130 grams) and the Starlight 1 at a claimed 77 grams (or 100!) This one is UK304.99 (Sept 2018) making it just about the most I have seen anything quoted on a per gram basis though!
I calculate this would have side flaps of approx 2.3 x 1.75 x 2.5.
There are a few other folk have a variety of cuben tarps (.51oz/yd2) around the 100 grams, so I think that is about the limit for now. Given that you could make your own in say a .9 oz Silpoly eg from Dutchware at US$5.20 /yd (Sept 2018) for around US$20 – I like the Dark Olive colour myself – (Minimum required for an 8’ x 8’ square tarp would be 3.6 yards), and that it is only just straight sewing (plus tie-outs) I think you should. It should weigh about 190 grams.
Such a tarp can do double duty as a hammock tarp with the addition of a 150-200 (inc suspension) hammock for a super-flexible camping system – you can use the hammock as a groundsheet when you are camping on the ground, so you don’t need the Polycro. You will notice I have sewn an extra couple of wings on my cuben one which weighed around 150 grams before I put the guys on it to provide just a little bit of extra shelter. This has added less than 50 grams to its weight (ie 8’/2.4 metres of .51oz/yd2 cuben). The ‘wings’ are the width of the cuben wide at the widest end – a bit over 4’6″. You can see it here: http://www.theultralighthiker.com/hammock-camping-double-bunking/ but this is a better method of double bunking:http://www.theultralighthiker.com/simple-hammock-double-up/
A snap on (Universal) Hemmer Foot such as this might make the job easier. I intend to purchase such as set before my next project.
If you wanted you could have a go at making your own Starlight 2 from the dimensions above. In the above material it should weigh around 180 grams. Happy sewing.
So, to conclude, the answer seems to be a minimum of about 70-100 grams in cuben; probably about twice that in the lightest waterproof nylon.
Other hammock related posts: