zzita, we all stack jars, I think, but I wouldn't stack any higher than you already have, which I think is 3 layers? That bottom layer is getting a lot of weight....

The NCHFP says:

If jars are stacked in storage, be careful not to disturb vacuum seals. It would be a good idea to not stack jars too high directly on top of each other; one manufacturer recommends no more than two layers high. It would be best to provide support between the layers as a preventive measure against disturbing the seals on the lower jars. Jars could be placed in boxes to be stacked, or use some type of a firm solid material across the jars as a supportive layer in between them."

So, if the boxes can be stacked with something in between, so the weight is on the box and not the jars themselves, you're probably good to go, but if the jars themselves are bearing the weight, I'd not go any higher.

Annie

Agree I have lost seals to over-stacking in the past. Now I never go more than 2-3 deep only then with 1/2 pints on the top. Plus I put a layer of corrugated box - just slice off a side - in between each layer to distribute the weight.

Assuming you are stacking with the rings/bands removed as recommended, if you already have 3 layers I sure wouldn't go any higher.

Dave

Thanks, folks!

I do have them the boxes new jars come in, which are rather thin corrugated cardboard.

I suppose it's better not to disturb them, but if I end up moving them in the fall, which I probably will, I could put plywood in between instead. It would distribute the weight better.