How waterproof is 1500 mm nylon?

[Gotte]

I've got a tent with a groundsheet that's a little porous now. It doesn;t leak badly, but gets a bit damp on wet ground. I was toying with the idea of getting a footprint for it, but then remembered I had a poncho. It fits just about right, and is waterproofed at 1500 mm. Is this enough to keep water out with pressure, like kneeling etc, or will it give after a while?

 

[JAG009]

Your going to looking for min 3000mm. good tents normally have between 5000mm to 10000mm groundsheets ,but if you are putting it under your tent ground sheet 3000mm should do the job
the 1500mm is a measure of proofing it is normally put in terms !500mm hydrostatic head this means it can support a column of water 1500mm in hight before leeking
hope this helps

Jason

 

[Gotte]

Thanks for that - so if it was doubled up, would it do the trick, or does it need to be one piece 3000 thick?

 

[sasquatch]

Try it and see...you could throw down an ipk and if that isn't enough throw the poncho on top of that. An ipk should be enough and only cost a few quid.

 

[Minotaur]

If it good material, you could treat it?