3 Story vs. 4 Story vs. 5 Story Apartments

by EVstudio AEP on August 2, 2018

We recently did a search for a good synopsis of the basic differences in costs and requirements for different heights/stories of apartment buildings. Finding none we decided it was time to fix that.

3 stories

Type VB construction does not require rating of the structural frame.
(Just ratings between units and corridors)

No elevator required
Ground floor accessible
NFPA13R
125/sf

4 stories

Type VA construction you need to rate ANY beam that fall under certain restrictions
Or
Type I podium with Type VB above 3 hr Floor
Elevator Required by ADA
All Floors Accessible (This means more Type B units, not that they are really changed from floor to floor)
NFPA 13R Fire Sprinkler System
150/sf

5 stories

Type III construction, 2 hr rated exterior walls (with fire retardant treated wood), and rated floors for Type IIIA
Or
Type I Podium with Type VA above 3 hr floor
Elevator Required by IBC and ADA
All Floors Accessible
NFPA 13 Fire Sprinkler System (Sprinklers in cavities)
Increased detailing for differential shrinkage of wood (Brick relief joints etc)
Increased shear wall detailing and increased structure on bottom floor

Image Courtesy of the American Wood Council

Image Courtesy of the American Wood Council

Originally posted 2014-11-13 07:55:57. Republished by Blog Post Promoter

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{ 4 comments… read them below or add one }

Dean Dalvit March 10, 2019 at 7:45 am

Hi Spencer, thanks for your question.
In the simplest analysis, there are two things that will drive that additional cost. The first is the elevator and the exit stair cores. That’s a costly item that layers onto a three story walk up product. In addition to that, the elevator invokes accessibility and exiting requirements you don’t have in a three story walkup product. But the far greater cost to going 4 stories is due to the finished interior corridor. This will add approximately 20% more building area for the interior hallways, elevator lobbies, entrances, etc.. And this is additional space that requires its own HVAC system, lighting, power, finishes, etc.. All of that cost has to be spread out over the units as you can’t really lease the common areas. Granted, you’ll have more units to spread that cost across, and typically, these are better buildings with more premium rents, so that’s something to consider in your pro forma as well. Having the interior space also lends itself to providing amenities in the building as well, which may also allow for higher rents depending on the market you are in.

Now, as far as complexity, a 4 story type V wood framed project isn’t really any more difficult to construct, so I wouldn’t caution you around considering it if you’re comfortable with three story walkup projects. Just a few additional things to consider, all related to those items above. But all of that should be spelled out in your plans from your design team.

If you haven’t yet assembled your design team, we would love to discuss your project with you. We offer Architecture as well as Structural, Mechanical, Electrical, Plumbing and Civil Engineering all in-house and have deep expertise in this type of project all across North America. We work regularly with our clients to assist them on everything from front end analysis, through design and construction, and develop long term relationships so we can apply all of that knowledge to add maximum value to every project you construct.

Please reply if you are interested in discussing further, and we can continue the conversation directly by phone or email. Thanks again Spencer and we hope to hear from you.
Sincerely,
Dean

Spencer Barber February 12, 2019 at 8:05 pm

I have a project right now that we are bringing through the entitlement process. Currently we are planning on going 3 stories and we’re doing exterior stairs. The city would rather have us go 4 stories and bring the hallways and stairs on the interior and use an elevator. The benefit is we get more units but we have never built a project of that size and are unsure of the additional costs that will bring to project. I see in the blog it points out to add an additional 25 per sq ft for this jump. I was wondering if anyone could share more details on what causes that jump in price. Thanks

Dean Dalvit October 18, 2018 at 7:28 am

Juliane,
That is because at five stories, you have to go from type V construction to type III construction. Can still be wood frame, but it needs to be fully fire rated and therefore is very uneconomical to do. As a result, you don’t see a lot of five story wood framed buildings.

Juliane Workley September 25, 2018 at 11:30 am

Great information. However, there is no cost per sf for the 5 story wood construction; only for the 3 and 4 story types.

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