Locus Gear Tyvek?

Tyvek is water resistant, not waterproof. And that new type 14 that seems to be the craze in the hiking world that last year or so is (understandably) even worse at water saturation. Highly durable, and water resistant – but not waterproof.

I have used my sublite in 12 hours straight rain and the tyvek completely wetted out.

Fortunately the living space remained drip free and dry as long as I avoided touching the walls.

I have been using a Ty-Sublite as well for several years starting with a prototype and later the production model that I currently use. The longest rain was an overnight rain in thevGrand Canyon several years ago and no problems at all. I live in California and hike in the Sierras. This is the climate it was designed for. It is perfect for me. It keeps the water out and I have never had a problems with condensation. I recommend Tyvek tents for folks with the same use profile as me. I have never used it in enduring, unrelenting rain.

I have fiddled with the Sublite Tyvek in my backyard.
My impression is pretty much the same as the one from Chris and John.
It breathes better than any other tent I have (PTFE/Epic/Polyester and several types of nylon and silnylon) .
It also very cool under a hot sun (afternoon nap…) and yes it will remain dry after hours of light to medium rain but I would not trust it under heavy rains nor high winds.
So a niche product that does what it was designed to do.

There are a lot of different versions of Tyvek out there with verying levels of hydrostatic head (waterproofness) and breathability. Tyvek 1443 is the most readily available version and it has a Hydrostatic head of about 30 inches and minimal breathability (dupont doesn't list a breathability rating for 1443). They don't list the tyek number on the web site but state it it is "soft Tyvek with UV coat". That might be 1460 tyvek which has a hydrostatic head of about 50inches and a breathability rating of less than 800 g/m2/24hrs. the hydrostatic head rating is high enough that it should stop all but the heaviest rain storms. The breathability rating is way below most waterproof breathable fabrics.

I don't have that shelter so I cannot state how well it actually performs.

I just love how theory does not always work in practice…
(it would if the theory was correct by taking into account all factores)