Sprinklers and fire separation with new R2 dwelling within an existing building

[Ryan Schultz]

I have an existing (3000sf) two story building with the following occupant groups and square footages.

• 1500sf (B) Tenant on 1st floor
• (2) 750sf (R2) tenants on the 2nd floor.

They would like to convert half the (B) tenant to a new 750sf (R2) tenant.

So the result would be.

• a 750sf (B) Tenant on 1st floor
• a 750sf (R2) Tenant on the 1st floor
• (2) 750sf (R2) tenants on the 2nd floor.

Per the code, I understand this new R2 unit, due to it's change in occupancy groups, needs to be sprinklered.

If we plan on just sprinkling the new 1st floor (R2) tenant, do we need a fire separation between?...

• ... the (B) tenant and the new (R2) tenant?
• ... the new (R2) tenant and the existing (R2) tenants on the 2nd floor?

If so, using Table 508.4, would that have to be a 1 or 2 hour separation? Not sure whether to use the 'S' or the 'NS' variable in this scenario.

Let me know if I can provide any further information to clarify this question.

Thanks Much, Ryan

 

[Francis Vineyard]

IBC Table 508.4 "is only applicable to that portion of the building occupied by the new occupancy classification (IEBC commentary)."

If the non-separated provision is applied in accordance with Section 1012.1.1; this will be a 1-hr. separation with the exception 2. of IBC 508.3.3 given the allowable building area and height.
NFPA 13R "throughout the area (residence) where the change of occupancy occurs (Ref. 1012.2.1).

 

[Ryan Schultz]

Thanks Francis,

It would seem, if I go non-separated, per EIBC 1012.1.1.1, that I would have to sprinkler the entire building--that is the remaining, non-sprinklered, (R2) and (B) units.

Is that not a correct interpretation?

 

[Francis Vineyard]

Thanks Francis,

It would seem, if I go non-separated, per EIBC 1012.1.1.1, that I would have to sprinkler the entire building--that is the remaining, non-sprinklered, (R2) and (B) units.

Is that not a correct interpretation?

Sorry; it would be correct to separate with 2-hr. and 13R only in the residence.

Note the commentary invites one area that is somewhat unclear is, where IBC Chapter 9 has a zero square footage threshold for sprinklers such as for Group R occupancies, whether the sprinklers would be required throughout or simply be limited to the new residence. That would mean separation between to new and old units can be one hour as if it was sprinklered throughout.

 

[Builder Bob]

Be careful with the two hour separation as this would also include the floor ceiling assembly between the first and second floor. This would become tricky as the separation is required to be fire barriers ----- the supporting construction for the second floor would have to be fire resistant rated for two hours as well.

 

[Francis Vineyard]

The 2-hour separation is between the R and B; the IBC permits a one-hour separation (horizontal) fire barrier between the R.

711.2.4.3 Dwelling units and sleeping units. Horizontal assemblies serving as dwelling or sleeping unit separations in accordance with Section 420.3 shall be not less than 1-hour fire-resistance-rated construction.

The exception to the above could be the construction type in accordance with Table 601.