TLDR Plumbing and windows.
Each unit needs its own kitchen and bathroom(s) which means you have to run additional stacks all the way to the sewers.
Commercial windows are allowed to be less efficient than residential windows because they are generally bigger, have more glass, and are made of more expensive aluminum.
You don’t necessarily need a full kitchen and bath in each unit–a toilet and kitchenette plus a larger shared kitchen and bath can work and will certainly lower the rent charged. There are a lot of brand new places going up that are doing just this.
It’s not the size of the room, it’s the number of drains. Nobody is building with shared bathrooms in downtown Boston, but even if they did, they would still need to increase capacity to account for showers on every floor.
I was guessing it’s “because they are offices”.
Thank you.
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it’s still less work than making all new buildings
This isn’t true. Well, it’s not true about 60% of the time. Here’s why:
- Office buildings–especially old ones–were often built with toxic building materials like asbestos (e.g. pipes, not insulation). If you’re renovating an office space these things aren’t much of a problem because as long as you leave them alone they’re not going to hurt anyone and most office renovations don’t require removing such things (and office space regulations are much more lax than residential for things like that). Converting an office to a residential space though requires removing toxic stuff like that which is very expensive. In these situations it’s almost always cheaper to demolish and rebuild.
- Office building floor heights are not the same as residential. It sounds simple, “so people living there will get extra tall ceilings… Who cares?” It’s not so simple! Even basic high-rise building codes require things like minimum air exchange and the ability to seal off areas to prevent gasses/smoke from fires freely moving throughout the building. In an office you usually have acoustic tiles and then like 2-10ft (sometimes up to 20ft!) of empty space above them. That’s not a big deal for an office that keeps the entire building/floor heated/cooled with several industrial air handlers but not so efficient (or safe!) if you have to subdivide that same space into several apartments.
- Running new plumbing to dozens of new locations on every floor is expensive because it requires cutting out large spaces for the pipes. Why is that expensive? Because safely cutting huge ass holes though floors and walls made of concrete and steel requires expensive building engineers and specialized tools that you don’t normally use in enclosed spaces that could contain a lot of toxic stuff. For example, using a jackhammer on a street or even underground in a tunnel only requires so much precision. Doing it at edge of a high-rise floor, 20 stories up is an entirely different matter.
There’s actually dozens of other more technical problems with such conversions. Nothing insurmountable, of course! Just expensive. Even just hiring a pair of lawyers–one versed in commercial real estate laws and one versed in residential laws–is going to be expensive.
I do love the “OH IT’S TOO EXPENSIVE SO WE SHOULD JUST DO NOTHING” comments you usually find in these threads. I’m pre-popping my popcorn.
You OK with the extra carbon footprint that expense comes with?
Is it bigger than the extra commute footprint?
I’ll allow you to be the first to shout from the mountain top that we should dismantle our economy.