What is a good choice for sealing plywood base so water from scenic spray doesnt warp it
I guess a normal sealant like Thompson’s Water Seal would work. Although it sounds kind of a waste as I doubt what little spray would get on the plywood would warp it unless maybe you were spraying the water out of a firehose.
I agree entirely. The plywood will only come unglued and warp with long exposure to wet conditions. Your sprayed or dribbled glue will dry in a few hours at most, assuming you don’t have high ambient and uncontrolled humidity. Besides, if you use the latex paint first, then ground cover and bushes, etc, I would let that dry, effectively sealing the plywood all by itself. Then, do an overspray of glue solution for better anchoring, and that should be all you need.
BTW, this may provide justification for those who, elsewhere in a very recent thread, were suggesting that the plywood base be painted BEFORE ballasting since that process does impart a fair bit of water to a small area.
I agree with painting/ sealing of the plywood as mentioned, howerver, you should not experiencing any distortion with your plywood unless it not fastened properly, much too thin for your needs or it is a poor grade of plywood to start with. The small amount of water and the short period it stays wet shouldn’t have any affect. Is this a plywood deck or subroadbed? What grade of ply is it and how is it fastened is what I would suspect first.
Bob K.