alternative to tarps for covering stacks of lumber

We have big stacks of lumber on racks outdoors that were covered with tarps to keep off rain.  I hate tarps as they fall apart in sunlight after a few years and also tear easily.

Someone is suggesting we use "panda plastic" which I see is also called "panda film" to cover the stacks instead of tarps.  I've never used this material before, but I imagine that like most plastic, it will eventually become brittle and fall apart in sunlight, and may also tear from falling branches and stuff (the racks are under big trees).  Does anyone have experience with panda plastic or panda film and know the answer to this?

We want to find a relatively low maintenance way to keep this lumber stored and not rotting.  It's almost all old growth redwood which is quite valuable and also rot resistant so it seems possible to store it a very long time if done right.  (We use it regularly too).  We just don't have an indoor space to store it all.  The tarps have worked but they are starting to get brittle and can't keep on like this forever.  We could put new tarps on that might last another 5 years.

Pond liner could work for longer, but it's around $1/sqft I believe, which is a lot.  I imagine pond liner degrades eventually too in sunlight, just not as fast as tarps because it's thicker.. so it's probably not any better in the long term.

How about used metal roofing?  Silicone blob on any nail holes and you're good to go...

plywood? maybe just build a simple shed roof?

For just loosely covering stacks, used metal roofing is pretty good, better than ply imo as it usually cheaper and lasts longer.

For lengths up to 8', old truck canopies are pretty great.

If the racks are suitable, I would be inclined to put permanent roofs on them; steel over small wooden trusses, probably.. easier to access the lumber, and there will always be a use for covered storage...

If its valuable D Nikols suggestion is good, create a low shed for it.

:)  Not surprised everyone's answer is to build an actual roof.  It's been moved around a few times so I think there's reluctance to build something permanent because it will probably want to be moved again someday.. but yeah I suppose a shed roof is always going to be useful for something anyway.

Well, if its been moved around a lot, any value it had may have been consumed in labour.
Why not sell it and use the cash wisely?

Philip McGarvey wrote::)  Not surprised everyone's answer is to build an actual roof.  It's been moved around a few times so I think there's reluctance to build something permanent because it will probably want to be moved again someday.. but yeah I suppose a shed roof is always going to be useful for something anyway.

Ah, the.good old farmyard shuffle... simply placing a thing usually increases the odds of needing that space for something else by about 8x...

Fortunately some consideration when building a modest shed can leave it relatively easy to move around later; pick it up with a loader, drag it with any number of machines, or jack it up and slide a trailer under it...