I bought my Waterlust kit the first day they were available back late in 2016. I was that excited to get going, I'd been following reports of the design's genesis here for some time.

Still, things being what they were with having moved 200 miles recently things were "unsettled" enough I had to wait almost three years before I could put epoxy to okoume ply.

When the kit's components were delivered mid-Febuary '17 I immediately unpacked everything to inspect for damage. Nothing but one puzzle joint lobe on a deck piece had suffered, and what damage had taken place was easily fixed when time came to assemble the deck.

Taking everything out of the BOX (it was a big, heavy one!) made it easier for me to shift parts to my basement, where they remained until I could commence assembly.

I stored everything flat on the basement floor, on top of the supplied corrugated cardboard box's top, after laying a piece of polyethylene vapor barrier on the concrete floor under the cardboard to avoid any potential problems with moisture and the plywood parts.

(If your chosen storage has any potential for water intrusion, look elsewhere for an alternative. Soon after taking up residence in our new abode I learned the basement was prone to minor flooding. It took me a couple of years to fix the various issues contributing to these events so by the time my kit arrived I'd seen no water present in over 18 months. Even still I was anxious every time it rained hard until I could get started with my build.)

As shipped, the kit's parts were standing vertically in the truck that made final delivery rather than laid flat, which may have caused what minor damage was evident. So from that I infer it's best to leave the flat parts flat if possible, or resting on the carton's longest edge if space is at a premium.

Before unpacking I took note of how well everything had been packed in that carton so as to preclude damage. Despite that there was but the one mishap, easily fixed with some epoxy & a bit of time.

   We've recently completed a teardrop in the custom shop that was stored for 4 years. The very slight warping was easily fixed. I don't think you'll have any problems if you stow it flat and raised off the floor in or out of the packaging. 

   Thank you both!

Great replies, and super fast as well.

I will take your advice, and store flat in the basement atop a vapor barrier.

I hope I don't have to wait too long, but I wanted to be safe.

It gets well below zero for days at a time here in the winter, so I should have plenty of indoor "quality time" coming up!

Thanks again...

   For long term, days/weeks/months, storing flat seems risky.  There's no exposure to air flow, and thus, evaporation.  Also, basements seem more prone to harboring moisture in the air due to being below ground.  Would recommend storing individual pieces upright, at ground level or above, leaning against a wall, with all four sides exposed, if possible, out of the elements.  A large jar of Damp Rid in the room can't hurt, helping avoid mold, sucking up moisture, and/or supplemented by a plug-in dehumidifier. 

My experience conflicts with what you're suggesting kurlanny.

Normal practice for storing full sheets of plywood is to have them stacked, laid flat with solid & uniform support. Storing on edge, unless held truly vertical, may induce cupping over time.

CNC'd plywood parts don't rest easy standing on edge or end, owing to the difference in shape and lack of support. Better to leave them flat as best you can, with largest pieces underneath the smaller stuff, re-stacking as needed once assembly's begun.

Humidity's another concern. Indoors is best with attention paid to uniformity and low degree of change. Obviously you want to protect from liquid contamination whether from above (leaks, condensation) or below (flooding). That stored components need to be accessable suggests keeping them at bench-height when possible, or perhaps under a bench or shelving as long as there's solid support once again and allowance for air flow around parts not wrapped/bagged in protective vapor barrier plastic.

Heated indoor storage humidity can vary quite a bit during seasonal changes but generally ought to stay between 40 - 60% which isn't going to cause problems as long as the CNC'd parts are well supported. Lower is better (up to the point where plywood can become brittle from being too dry) and higher than ~ 60-65% RHI may suggest some means of moisture removal should be engaged.

If you use DampRid (Calcium Chloride) for this you need to monitor the accumulating liquid which is very corrosive to steel tools and should be disposed of properly while also avoiding spillage. Too, its effect is best limited to the smallest volume of space to be kept at a lower humidity so 'tenting' your storage in plastic sheet may be helpful.

Once all the solid CaCl has been dissolved its usefulness is over and should be refilled/replaced. High ambient humidity can be mitigated with a space heater or the electric dehumidifier you've mentioned.