Sometimes, when the popcorn ceiling has been painted it takes a little more time for the water to penetrate through the paint.

Excellent advice that I will embrace.

Here are my 21 tips for starting out:#1 – Learn From Others#2 – Plan to Market#3 – Know Your Type (Performing, Non Performing, Re performing, Investor Notes, Seller Financed, etc)#4 – First Refer A Deal#5 – Discover The Why Behind the Note Sale#6 – Get To ‘Know’ The Payer#7 – Verify Everything#8 – Embrace The Boring (Due Diligence Counts)#9 – Plan for The Worse#10 – Partials Are Your Friend#11 – Master The Time Value of Money#12 – Encourage Early Payoffs#13 – Originals Count (Get that original note and endorsements/allonges)#14 – Stay In Control#15 – Seek Professional Help#16 – Use Solid Servicing Procedures#17 – Understand When Laws Apply#18 – Get Self-Directed#19 – Spread The Risk#20 – Know When To Fold#21 – Be Creative If you PM me here on Bigger Pockets I can send you details on the individual tips. 

Improper or no drainage system can result in condensate penetrating your window sill/trim and/or leaking to the interior of your structure ultimately causing extensive wood rot and other water related damages.

Although I have had on two occasions found a drywall screw that penetrated a copper supply pipe during the normal course of construction (the pipes were not properly placed or protected), when the screws, after several years, corroded enough to spring a leak.Wax rings and supply line/stop valve replacements are also always going to be Owner responsibility, absent clear evidence of intentional physical damage.

Embrace the "slow" and tedious...

I agree with others on painting, if you can, without causing future issues with water penetration etc.  

Any repairs, service, replacements roof repairs/penetrations - anything.

I'm not sure of your background, but really embrace the education process.

Rather than risk time and money tackling a difficult problem alone, successful real estate investors know it is worth the additional costs (in terms of money and ego) to embrace other people’s expertise.10.