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Discussion Starter · #1 ·
I need some experienced guideance on how to waterproof the underside of a number of decks I have. I'm located in Truckee, CA so I have to deal with snow and ice. I would like the option of running electrical through the ceiling but it's not mandatory. I've been looking at Under Deck and Rain Tight. Under Deck doesn't work for me because my joists are not evenly spaced (don't get me started!). I would prefer a DYI solution over a prefab install if I can save some $. Any ideas or experiences with either DYI solutions or prefab products? Thanks in advance for any replies!
 

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Low Slope Roofing
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One thing I can think of that would be quick and easy would be to use a flush reveal wall panel. It would also at the same time have a nice finish for the bottom of the deck.



Hang them from the underside depending on the what way you run the panels and what way the joists runs you may have to add some 2X's to have something to attach them to. May need to slope it the direction you want them to drain to.

Then they could just spill out in to a gutter.


I generally prefer to waterproof on top of the deck but this may or may not be possible.
 

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I actually just did this and did a bunch of research before I did. Now I was rebuilding my deck so I was able to use a very cost effective product called Rainescape by Trex and it's working great. Unfortunately that's only an option if you can apply it before you put down the decking. There are many, many systems that are secured to the bottom of the joists and double as a ceiling, but I found virtually all of them to be quite expensive.
The only DIY approach I even considered was one that uses those PVC roofing panels that are wavy. You can get them at Home Depot. You would need to rip long strips at a slight angle and nail/screw them to the bottom of your joists to apply a pitch to get the water to move away from the house. You then attach the PVC Roofing to the joists, overlapping as you go. From the DIY's I read, it seems to work pretty well but you would need to get creative if you're going to run electrical since it would be in the wet zone. You also would need to deal with water coming down the siding on of the house. You would need some kind of flashing to move the water from the house siding to the PVC roofing. At the other end you could run the roofing into a gutter attached to the bottom of the Rim Joist, or just let it run off the end.
It's not the prettiest method, but it's certainly the least expensive.
 

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Discussion Starter · #4 ·
Thanks for the advice. I had the same idea for a DIY solution and have it pretty well mapped out. Thought about then putting some siding across the joist to cover it up. But I might redo the top boards anyway and would definitely do the other option in that case. Thanks for the confirmation.
 
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