How to change the space under my deck to DYI workshop?

We used verigated galvanized tin, shimming under the last three deck joists to create a slight angled grade on the tin so the water drained from under the decking surface in one direction. Each sheet was joined to the next by slightly overlapping and caulking every joint and around/over each screw head, attached with a rubber washer. We then enclosed the space around the vertical edge to create an awesome, weather sealed space for secured storage of summer lawn equipment, winter snow removal equipment and off season items like water toys, lawn chairs, and winter/summer tires for vehicles. We put a padlock on it to discourage thieves. That was 12 years ago! No leaks or issues as of yet, and living in Canada I think that’s impressive! Warmer climates could use fibreglass panelling and get similar results! Happy woodworking and All the best!😊

Candace is right, you basically have to build a roof UNDER the deck to keep the rain from draining through. She has an excellent solution. No matter whether your weather is as cold as hers or is warmer rain is still the problem. A tarp will give you a quick fix and may be all you are interested in. Corrugated tin or fiberglass panels are probably the best for a long term solution.

They actually sell "gutters" just for this kind of situation. Here's a youtube video on how they're installed so you can get a look at them. https://www.youtube.com/watch?v=PGAededTruk

Hello, hope this helps you out,

https://www.youtube.com/watch?v=62ZYa0nbhDs

tin is used to keep the water out

I think you would have to have a very sturdy and well insulated room built under the deck. You'll want to keep out water from above and keep out the rain!

They make under deck drainage systems just for that purpose! https://www.youtube.com/watch?v=ObuFCtqLXRE