Left my insulation rolls outside in the rain and they turned out fine

Similar thing happened to me last year, though mine was my own fault. I'd stored a few packs of Pink Batts under the house ahead of a bedroom reno, and a leaking downpipe soaked one of the packs without me noticing for a week. By the time I found it the outer batts were soggy and the pack had gone a bit misshapen.

I rang the manufacturer's helpline about it and they said the same thing basically, that glass wool dries out fine as long as it hasn't been sitting wet long enought to grow anything. They told me to check for any discolouration or smell, and if it looks and smells normal after drying it's good to go.

I laid mine out flat on a couple of timber racks in the shed with a fan going for about four days, flipping them halfway through. One batt had a slight musty smell even after drying so I chucked that one and used the rest. Two winters on, no issues in the wall cavity at all. One thing I'd add to what you did, don't squeeze the wet batts back into the pack to dry them compressed. I did that with the first couple and they took way longer to dry and never quite bounced back to full loft, so I ended up leaving those ones out of the job.

I'd have baulked at leaving them standing for three days personally. When my ceiling batts got rained on during a renovation a few winters back, I didn't have the patience to dry and inspect them, so I just rang the supplier and had the whole pack swapped under delivery insurance. Cost me nothing but a week's delay and it meant I never had to lie awake wondering if there was damp hiding in the middle somewhere.

The other thing I'd flag is that a soaked batt can come up fine on the surface but end up slightly flattened or lumpy once it dries, especally near the corners of the pack. If the wool doesn't spring back to full thickness, you're losing performance in the spots that matter. When I checked the replacements against the old pack side by side, the difference was obvious. So drying works for some people, clearly, but if it was delivered damaged, that's the supplier's problem, not one you have to solve yourself.

Did the same sort of rescue with some ceiling batts that got caught in a storm while the roof was off. What actually saved me was borrowing a cheap moisture meter from a mate who does flooring. I'd been going off feel, wich is hopeless with glass wool because the surface dries way before the middle. Took readings in a few spots each day and only installed them once the numbers matched the dry batts from another pack. Made the whole thing way less of a guess, and none of them have given any trouble in the two years since.

Good to hear it worked out. I'm doing my loft soon and the delivery slot they gave me is a day I'll be at work, so this is honestly reassuring to read. Does the fluffy stuff go flat and stay flat if it gets squashed while it's wet, or does it spring back once it's dry? I've got no room to lay it all out flat, my plan was just to shove it straight up there if the weather holds.

To answer your question, it does spring back if it dries while it's got room to fluff up. If you squash it wet and let it dry like that, it tends to stay thinner, which kills the R value a bit. Mine came good after I draped a couple of batts over a clothes airer in the garage, so you don't need heaps of floor space. Just don't bung them up there damp, they won't dry properly once they're sealed in the cavity.