Could you please share experience of owning 100+ yr plex? I've never owned a plex, but am seeing a 117 yr old triplex interesting. Looks like it can generate a good cashflow, but I'm not too sure what kind of headache I should expect with 100+ yr old plex.

@Chanitnan K. To help responders you should illuminate the type of plumbing, if the electric is knob-and-tube, etc. Some of these “big” items are either issues that have been dealt with or will likely need to be dealt with.

I have a 4-unit is from 1903. It's pretty amazing. The electrical was fine. Some plumbing was updated as part of the sales agreement. The bones are very good. It was a SFH that was turned into a 4-unit around the year 2000.

There was some leaking in the basement when it rained (literally every property I have purchased has had this issue because most landlords had slumlord PMs working for them) and I fixed that issue on my own using mortar (it costs under $2.50 a bag at Lowes). 

My newest property was built in 1917 - that had knob and tube - but not a lot of it. I paid $1900 to have it removed and replaced and to have some upgrades made (added some lights, moved some light switches, etc.). 

If you move forward, definitely get a good inspector in there as he'll point out what needs replaced and perhaps you can get the seller to pay for some/all the repairs. 

On my 1903 4-unit the seller paid for a lot of needed repairs/upgrades. 

Though old homes tend to have inferior windows. My newest property has some new windows but a few aren't very nice. One is definitely badly in need of repair (it seriously has paper towels stuffed in a crevice toward the top) and I'm paying $335 installed to have that window replaced (they had to special order it). 

As a general rule, I never buy anything over 115 years old. Lol.

Thank you! @Karl B. what type of plumbing did the building have and what did you update it to? And how did you tell the bones of the building were good?

I own a 1912 duplex. You just need it to be inspected properly. As others said main concerns are knob and tube, windows and plumbing. In my case all of those have had to be updated. I have had multiple experts tell me my foundation is in tiptop shape. 

One annoying thing is horsehair plaster walls - still have those. Embrace the picture rail at the ceiling.

My original roof, made of VT slate (this is a common New England material for roofs) could last 150-200 years total with regular maintenance. I just did a big repair to it in January of this year because of past neglect but am expecting it to last for a long time and perform better than a shingle roof. 

In some cases the materials and work quality is higher in something this old than in something you build today. All depends, though so you have to be very careful. Something could have been made cheaply back then just like it could be made cheaply or well today.

@Chanitnan K. No problem. Thank you for thanking me. :-)

Some of the plumbing had been updated - the seller paid for that. The big problem (according to my plumber whom I recommended to the seller and performed the repairs) is the cast iron drains, which rust and then cause leaks. I didn't actively replace them but of the plumbing repairs that were made prior to sale...  there was a leak in a pipe underneath one toilet and that plumbing (and floor) was repaired, the main stack pipe in the basement was replaced and some minor unrelated repairs were made (one sink was missing a pipe - seriously, some drain clogs, etc).

In the duplex I bought on July 31st there was a plumbing issue prior to me buying it (2nd floor bathroom pipes). They had to bust a hole in the ceiling to get to the pipes. And so when I bought the place the piping was showing in the 1st floor closet due to the hole. I had my handyman install a removable ceiling in the event we need to access those pipes again. 

Prior to sale you can always have a plumber meet with you to check out the property you may want to buy and give you recommendations are far as potential issues. If you've worked with a plumber a few times he shouldn't charge you for this.