The Cost of Triplexes vs Group Living

I've gone from renting a large house with 5-7 people for the past ten years in Philadelphia to living in a unit of a triplex that I own.

As part of this process, I've been amazed at how more expensive it is to run a triplex than a large home -- with an equal number of people and the same square footage. A lot of my goal of being a landlord is to provide affordable quality housing. This means that I try to keep unnecessary costs low, as our rents are directly based on our costs.

Here are some of the additional costs

1. Philadelphia homestead exemption
The city of Philadelphia just created a property tax homestead exemption. If everyone lives in the same house and someone owns it you get the full $30,000 exemption. If you live in a third of the house you only get $10,000.
Cost of triplex: $20,000 * 0.0134 (tax rate) = $268/year

2. Hard wired smoke alarms
If you have a house you can get about the same quality of fire detection without having to have a hard-wired system. If you have a triplex, it can cost several thousand dollars to install the system (our's cost $4500 -- one of our biggest house maintenance costs so far and one that did almost nothing to improve the residents safety or living experience -- in fact it likes to lose its phone connection and emit high beeping noises which annoy everyone) and then $50/month to maintain it (annual inspection, two cell phone lines, and alarm service).
Cost of triplex: $600/year (not including installation)

3. Trash service
A single home doesn't pay for trash service.
Triplex: $300/year

4. Separate utilities: electric and gas
We have four electric services and three gas services. A regular home needs only one of each. That is cost of around $50/month in flat fees (fees that don't depend on usage). In addition we need to maintain three gas water heaters (cost of 2*$1000 every 12 years). This doesn't include the additional electrical work from maintaining four electrical panels and extra water piping.
Triplex: $300/year + $160/year= $460 year

5. Separate utilities: Internet
A single home can share internet service. In Philadelphia the cost of basic high-speed internet is $55/month.
Triplex: $110/month or $1320/year
If you have triple play - tv, phone, and internet - the cost of the triplex is $200/month or $2400/year.

Total extra costs for a triplex: $2948/year.
The extra costs of running a triplex compared to a single family home are as high as 10% of the total cost of rent in my neighborhood (or 7-8% of the cost of rent plus utilities).

So what do people do? My guess is that many people are sharing internet service or not getting it. That they are using mobile phones and not getting cable tv. I suspect the rule about a hard-wired fire alarm system is widely ignored. I wouldn't be surprised if a lot of people weren't paying their trash service fee or getting a rental license. And there might be some people who are running the entire house off a single electrical panel, and/or a single gas water heater (the latter is probably legal and actually a pretty good idea so long as it is big enough).

6. Rental License
If you are just renting out rooms in your house, you can probably avoid this.
Triplex cost: $150/year (debatable)

There might be additional costs that I'll think of later and add.