I ride motorcycles and I camp in a tent, even when it’s raining. I’ve suffered the indignities of waking up to find puddles of water sloshing around in the tent, and I’ve spent sleepless nights shivering in a wet sleeping bag because of those puddles.
The cause of my discomfort wasn’t the tent itself, instead it was the “ground cloth”.
This article shows the construction of an inexpensive, waterproof ground cloth made from Tyvek sheeting.
Click the link to view the PDF file: Tyvek Ground Cloth For Your Tent