Building "townhouses" but prefer to classify as R2

[jbplaster]

Hello everyone, longtime reader first time poster. Usually I can navigate the Code pretty well, but this one is tricky.

Here's my situation. I have a 4-unit townhouse development, adaptive re-use building on top of 4 single-level business occupancies. The existing lower level of each unit will become the lower level of the each new 2-storey townhouse. These are separate parcels, now under single ownership. The units are very small, 400-700 square feet per floor. Trust me, I would rather tear it down and start from scratch, but there are local reasons for going this route (boutique town, grandfathered footprint).

Townhouses would require 2-hr separation, with independent structure on each side. Tough to do this over the existing first floor walls. We also have to protect openings 4' on either side of the fire walls between units, same for the roof, etc. Because these units are so small, this is limiting.

If I call it R2, we have to sprinkler the whole "building" but can use NFPA 13R, so it's not a deal breaker. And my separation goes to 1-hour, with no independent structure required because I'm now building Fire Partitions between units. And opening protection either side of the fire partitions is not required. Same for the roof.

I guess the question is, can I classify this as an R2 building? And is there anything else I'm missing? Assuming the parcels would have to be re-combined into a single parcel.

Thanks
Jesse

 

[mtlogcabin]

These are separate parcels, now under single ownership.

We would require a binding lot agreement that legally binds the lots together so they could not be sold separately without the cities permission. Then the IBC could be used.

 

[Joe.B]

We would require a binding lot agreement that legally binds the lots together so they could not be sold separately without the cities permission. Then the IBC could be used.

Exactly. In my opinion, the only reason you would design them like "townhouse" units would be to take advantage of separate lots and the ability to convey them separately. If that's not happening, you're far better off designing them as "multi-story units" within an R-2 building.

 

[jbplaster]

Agreed, and if the owner wanted to sell down the road, he could sell them as condominiums.

Thanks all, I think that's my talking points to the owner.

 

[jar546]

We would require a binding lot agreement that legally binds the lots together so they could not be sold separately without the cities permission. Then the IBC could be used.

Is that in the zoning ordinance? The reason I am asking is to clarify if your building code regulates form of ownership.

 

[jar546]

This is where our definition comes in handy:

[A] TOWNHOUSE. A single-family dwelling unit not exceeding three stories in height constructed in a group of two or more attached units with property lines separating such units in which each unit extends from the foundation to roof and with a yard or public way on not less than two sides.

 

[jar546]

I would rather tear it down and start from scratch

Can I assume these are not in a special flood hazard area?

 

[jar546]

If they want to take on the additional requirements of R-2, that’s their choice, but the building department still has a reason to question whether the classification aligns with the actual lot configuration and building form. R-2 assumes a multifamily building on a single lot, not individually owned parcels. If each unit sits on a separate lot, how does that impact fire separation, shared systems, and future sales? R-3 townhouses require 2-hour fire-rated walls (1-hour if sprinklered), but R-2 allows 1-hour fire partitions under the assumption that the entire structure functions as one. If these are separate parcels, does that create a gap in fire protection when ownership changes? Accessibility also comes into play—R-2 requires compliance with Fair Housing and, in some cases, ADA, which typically doesn’t apply to townhouses. Then there’s the zoning issue. Does zoning even allow R-2 on separate lots? The concern isn’t that R-2 is more restrictive; it’s whether R-2 actually fits this project based on lot division and future ownership. If everything aligns with code and zoning, great—approve it. But if they’re using R-2 to bypass townhouse firewall requirements while still treating these as individual units, that’s where things get messy.

 

[steveray]

Interesting with the R2/ lot line twist as the min. FW is 2hr....

706.1.1​

Any wall located on a lot line between adjacent buildings, which is used or adapted for joint service between the two buildings, shall be constructed as a fire wall in accordance with Section 706. Party walls shall be constructed without openings and shall create separate buildings.

 

[mtlogcabin]

Is that in the zoning ordinance?

Yes it is

 

[Joe.B]

Yeah, that's interesting. It's a little different here because you're going to have it sprinklered either way, so in my mind there's no real advantage. We had a couple of apartment project built like townhouses, but they weren't technically because (as @jar546 pointed out) there were no lot lines running between them. That's just the way this guy learned to design and build so that's what he did. Because they were more than 2 units in one building, they were R-2 regardless, so to me it seemed like a lot of extra work for not much advantage...

 

[jbplaster]

Can I assume these are not in a special flood hazard area?

Not flood hazard. I just said I'd rather start from scratch because it's kinda fitting a square peg to a round hole. But without the grandfathered use, the project would be unfeasible.

 

[jbplaster]

If they want to take on the additional requirements of R-2, that’s their choice, but the building department still has a reason to question whether the classification aligns with the actual lot configuration and building form. R-2 assumes a multifamily building on a single lot, not individually owned parcels. If each unit sits on a separate lot, how does that impact fire separation, shared systems, and future sales? R-3 townhouses require 2-hour fire-rated walls (1-hour if sprinklered), but R-2 allows 1-hour fire partitions under the assumption that the entire structure functions as one. If these are separate parcels, does that create a gap in fire protection when ownership changes? Accessibility also comes into play—R-2 requires compliance with Fair Housing and, in some cases, ADA, which typically doesn’t apply to townhouses. Then there’s the zoning issue. Does zoning even allow R-2 on separate lots? The concern isn’t that R-2 is more restrictive; it’s whether R-2 actually fits this project based on lot division and future ownership. If everything aligns with code and zoning, great—approve it. But if they’re using R-2 to bypass townhouse firewall requirements while still treating these as individual units, that’s where things get messy.

Just to clarify, I'm the architect. I'm assuming the lots WILL have to be combined to go R2. There are downsides, but I think these are outweighed by the design flexibility I get from R2. Townhouses would require opening protection 4' either side of the fire walls, and these are such small lots that this would kill the project.

 

[jbplaster]

Interesting with the R2/ lot line twist as the min. FW is 2hr....

706.1.1​

Any wall located on a lot line between adjacent buildings, which is used or adapted for joint service between the two buildings, shall be constructed as a fire wall in accordance with Section 706. Party walls shall be constructed without openings and shall create separate buildings.

Exactly. The lots have to be combined and the whole project goes R2, eliminating the structurally independent fire walls and associated impacts on exterior walls. It looks like a townhouse, but works better as R2.