Soggy paper.
Never a good thing, and a difficult salvage job.
Much of your paper may have originated from digital systems, which hopefully are backed up offsite. Some routine paperwork may not be a big loss. But some paperwork may be critical, and you do not want to lose that.
Critical Documents:
Entity legal documents, board minutes, licenses, tax returns, blue prints, warranties, vehicle titles ..... all of these may be critical to your business operations, and some may be difficult to replace.
Advisors and Vendors:
Your CPA and attorney should have backups of some of these documents (if your CPA or attorney office is in your same neighborhood you should ask about their digital backup planning). This can be a great help, but advisors will not have day-to-day paperwork. If you use a payroll service the service will have digital backups of your payroll details. Your bank will have digital copies of your banking records for multiple years.
Digitizing Records:
A flatbed scanner can be had for less than $100 dollars, and is handy for quick scans of small numbers of documents. A faster document feed scanner can be had for under $300. These allow the capture and backup of digital images. This allows for easy digital backup offsite and can cut your file cabinet usage.
Not the Basement:
Many commercial building have basements, and it provides for close but out-of-the-way storage.
Basements are also the first to flood. Bad place for paperwork.
Retrieving and rebuilding your records is time consuming and costly, which justifies the time required for backups.
Assess your risk. Some locations are riskier than others. All locations have at least some fire risk, and most have some level of wind risk. And some are in hurricane zones.
You may be lucky, you may not. Do not depend on luck.