One building or two?

[cpdga]

The architects in my office disagree on whether this building is 1 building or 2. Six of us have looked at it so far and we're split. Location is California.

Here's a link to some diagrammatic plans:

https://imgur.com/a/VdwZ0Wq

The existing building overall is L-shaped - west half is called "Building A" and east half "Building B." The project information in the IFC for the shell is inconsistent. Sometimes it refers to the project as "building," singular, and sometimes "buildings," plural. The campus permits SDP/PDP/NDP project description clearly says "two buildings." The grading permit also clearly says "two buildings." The allowable area calc combines the total SF for both buildings. The permitted area combines the total SF for both buildings. A and B each have their own addresses. Type IIB, warm shell permitted with B and S-2 occupancy (the TI will add A occupancy). Three stories over two floors of basement. Grade plane is at Level 1. The two buildings are connected in the interior on Level 1, with an occupancy separation. Levels two and three are separated by a shared patio. The site plan shows the closest dimension between the two at about 25'. The link above shows which walls are rated.

The proposed control areas are also at the link above, last image. One person says control area 1A is only a Level 1 control area, even though it extends vertically into L2 and L3 (two-story lobby and three-story stair, all 1hr encapsulated). Two others said, no, at L2 you have four total control areas: 1A, 2A, 2B and 2C. So, one control area too many if it's one building. My PM says we need to deluge the curtain wall at the east elevation of L2 and L3; is that true?

Our control area questions would be resolved if we can determine if this is one building or two.

 

[Mark K]

If you want it to be treated as one building the drawings and calculations should not make reference to building A and building B. Revise the drawings associated with grading permit to remove reference to two buildings.

From a structural perspective it could be treated as one building. If the parking extends above ground level I would rethink the configuration of the parking. Talk with your structural engineer. A seismic joint between the two wings might make sense

 

[mtlogcabin]

Do they have separate utility services? Water, Electrical, Sewage, Fire Suppression?

 

[cpdga]

Do they have separate utility services? Water, Electrical, Sewage, Fire Suppression?

Yes, utilities and metering are separate. I'm not certain about FS, I don't have as-builts or FS/FA drawings yet.

 

[mtlogcabin]

(the TI will add A occupancy).

The "A" occupancy requirements will apply to both structures.
503.1.2 Buildings on same lot.
Two or more buildings on the same lot shall be regulated as separate buildings or shall be considered as portions of one building where the building height, number of stories of each building and the aggregate building area of the buildings are within the limitations specified in Sections 504 and 506. The provisions of this code applicable to the aggregate building shall be applicable to each building.

 

[Tim Mailloux]

your plan identifies fire rated walls, but we don't know if they are fire barriers or fire walls. If you have a fire wall with two separate independent structural systems on either side of the fire wall you have two buildings. If those rated partitions are fire barriers and both sections of the building are part of one structural system you have one building.