canvas tarps

Canvas leaks when flat, but may help some. Good to keep snow off though.
Canvas rots when damp. Lost a nice canvas tent when I put it away damp.
Better to not cover than use canvas for most of the year. Better air flow with out it. IMO.
To me the rigid covers are the best, pieces of metal roofing (Like BWS uses) or painted plywood at a slight angle so the water runs off & still good air circulation, if you can keep them on in the wind..
If the wood is good & dry. Carbon_Liberator uses old lumber yard tarps nailed/screwed down to hold in the wind. https://www.hearth.com/econtent/index.php/forums/viewthread/81797/P18/#991387
"Covering or not covering" is an on going debate here, I think both have merit for certain conditions.
I have a bunch of spruce uncovered & it dried/seasoned well.
If I was going to use it this winter, I'd cover it similar to CL method to keep the snow off & make it easier, snow free access when needed. Wind here would blow the metal roofing a long ways off. (been there, done that)
Not even sure CL method would work with our wind, but it's a better method than I used when I used tarps.

Agree with Dave. Canvas does not make a good cover for wood. The wood is better off without any cover than to use canvas.

There's all kinds of canvas available. Plain canvas will rot very quickly, but awning canvas is awesome stuff that will take an incredible beating and won't rot because it is impregnated with some sort of vinyl. We dabbled in recanvasing awnings some years ago to make a few extra bucks. I have some nice remnants that I've used for years to cover stuff and they're still usable. If you can get some of that stuff it will make a very durable cover. A grommet holds very nicely in the stuff as well.

BTW anybody want a commercial sewing machine? My wife insisted that we sold it years ago, but I just found it the other day under a pile of fabric while I was packing up my old darkroom. You can take the sewing machine for free, but you have to take all the fabric as well. ;-)

I tried using a canvas tarp to cover my hot tub when it was going to snowcover. When it snowed, it was fine. When it we had mixed parcipitation (rain, snow, sleet), it got wet and then it froze. Once it froze, it hardened. I would not recommend canvas, go vinyl.

I have roughly 1/2 of an old awning from parents old motorhome before they sold it some years back.Temp firewood cover for a few weeks,since then its been covering a bunch of reclaimed Hard Maple,Birch & Birch plywood on outdoor workbench.Gets very stiff in cold temps & sounds like its gonna break in two,but keeps things dry underneath with no holes or weather damage yet.Its probably at least 20 yrs old now.

Try to contact a commercial roofing company that utilize rubber roofs. The old rubber roof or large scrap pieces of new are ideal for covering the top of a wood pile. I was fortunate to get alot of it a few years ago and use it on my wood piles. I cut the pieces 5 feet by 10-15 feet long, secure a screw eye into a few splits near the ground and run a rope from the cyclone fence ( adjacent to my pile) to the screw eye every four to five feet to secure it in case of high winds. The rubber roofing will last for years.

I found an old spinnaker sail from a very large sail boat for free on craigs list. Sail fabric is idea to cover wood as it is water proof an very tough. But the shape is not always ideal unless you build triangular wood piles. If given the option to only use boat sails, I would. They last forever whereas I only get 2-3 years from expensive tarps.