Can I include shared space when calculating expenses/depreciation for a room I rent out in my house? TT instructions say to only use sf of the room; IRS says it's okay.

IRS Publication 587 (Business Use of Your Home): While this primarily applies to home office deductions, it uses the same principles for dividing personal vs. business (or rental) use of a property. It explicitly allows a proportional share of common areas to be included when determining business use percentage. The IRS allows reasonable methods of allocation, with square footage being the most common. Are TurboTax instructions incomplete for this issue?