How I Turned Wasted Space Into Under-Deck Storage With a DIY Corrugated Ceiling

We FINALLY completed a massive deck expansion – going from roughly 15′ x 18′ to a 40′ x 18′ deck. We built on, we maneuvered the stairs to better fit our yard and the natural flow of our space and finally was able to finish it all off with a new coat of solid stain. But what was bothering me during our deck expansion was seeing how much potential was UNDERNEITH the deck. I saw untapped storage options under there that I knew I had to take advantage of. So I did what any sane person would do, I made the deck project EVEN LONGER by adding a watertight ceiling, enclosing the space in, and even incorporating an 8′ drawer to the lowest point so we can still maximize even the area that was too small to crawl in. So let’s get into how I took under my deck and made it into massive storage instead of an area that otherwise would be…nothing.

After clearing out under the deck, it was important to me to make it completely water tight so we could store our lawn mower, snow blower, wheelbarrow, etc. without getting rained on or getting rusted out. One option would have been to install underdecking directly over our joists BEFORE installing our top deck boards, but this idea came to be a bit too late, so we had to go with option two. I purchased enough PVC corrugated panels to hang from directly to the bottom of my deck joists, accounting for a slight overlap on each.

Since decks are completely level, you will need to create a slope leading to whatever end you are rerouting the water (with a gutter system or a straight runoff). I did so by cutting leftover pressure-treated 2x6s into blocking and attached them under my deck joists. I cut my first set of blocks at 1″ pieces, then my next set at 1.5 inches, then at 2 inches, and finally at 2.5 inches. You will need to cut however many are necessary for the size of your deck. I attached 5 to each joist and spaced them out by putting the next larger blocks 3 joists past the last one.

After attaching the blocking, I attached a 2×4 to the row of blocks so I had one solid piece to screw the corrugated panels into.

**If you are wanting to install the 8′ hidden drawer I’ll share with you tomorrow – you will need to attach your 2x4s to your deck joists vertically in their locations NOW, before attaching your ceiling panels**

I installed these using 3″ SPAX screws that are completely rust-proof and include a small rubber washer to keep moisture from dripping through. Looking back, my biggest piece of advice would be to have a second person help you as you are installing as they are flexible AND 8′ long. It was very difficult to keep them in a straight line while trying to attach.

I would also be sure you are starting at one end and working your way across your space so the panels aren’t bunching and causing them to not lay flat on the ceiling.

I attached the screws every other ridge to allow for water to be able to run smoothly down each panel and not be too pinched. Each time I had to add another panel, I was sure to use a significant amount of sealant so no water would cause issues in between each panel.

All of these materials I used can be found HERE:

At the end of the panels, I installed a gutter system to allow the water to flow off the panels, into the gutter, down the drain pipe, and out into my landscaping outside my deck.

The gutter is extremely inexpensive from your local hardware store. I chose to go with a 5″ gutter in the event of any heavy rains we may get here in the midwest.

Your gutter will also need to have a slight pitch to it so no water sits in it and instead, flows smoothly down to the drain pipe. I followed the order of about a 1/2″ slope for every 10′ of gutter. I capped both ends of the gutter and cut out a hole for my drain pipe to attach. This does require several pieces but each of the pieces needed are extremely inexpensive and easy to work with. I followed THIS TUTORIAL to help me with this installation.

Once I had the ceiling attached and the gutter system in working order, I tested it for any small leaks I may have and fixed those by adding waterproof exterior sealant to the area. I allowed to dry for 24 hours and retested. I really wanted to be sure I wouldn’t have leaks before moving in my tools.

When it was fully sealed and water tight, I rolled out 40mil plastic sheeting to the space to kill out all the weeds and ivy that were under the deck and to keep all the mosquitos that tended to lay eggs under my deck at bay. Using a local Facebook Marketplace, I had 2 tons of gravel delivered to my driveway and moved the gravel back on top of the sheeting.

This is just step one of this under deck storage. There is so much fun stuff to come with this space! Stay tuned for tomorrow where I share the under deck 8′ hidden drawer that has been a game changer for storing all my shovels and rakes!

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