Change of occupancy from residential to commercial

[Sifu]

This one is worrying me. I briefly posted about it in another thread but got no bites. Now the mayor is involved. Lots of typical small town backstory but I stick to the code. The following is the process and determinations as I see it, but I am not sure and have a couple of concerns....hence my post. Bear with it if you have the time.

2018 IBC, IEBC, IRC. The existing situation is 1 residential lot, with an SFD, and two residential accessory structures. The highlighted structure is being proposed to convert to a commercial establishment, mixed-use, non-separated, B & M. All wood frame, no sprinklers. Keep planning & zoning out of it by assuming it is approved.

Both the IRC and the IBC would have the applicant establish an FSD, which would be an imaginary line since all one lot. (3rd review, they still haven't done this)
The IEBC has no provisions for IRC regulated structures, but for arguments sake lets call the house an R3, and the accessory buildings U.

First I deal with the IRC, and t302.1(1). Once established, any portion of the SFD within 5' of the FSD would be subject to t302.1(1), therefore the SFD walls and projections (and possibly openings) will need to be rated to some extent depending on where they establish the FSD. (I acknowledge that IRC t301.2(1) may only be considering separations form other IRC regulated structures but it's what I got right now.)

Second I deal with the IEBC, and section 1011.6, t1011.6. In order to use the IEBC an occupancy classification must be assigned for everything. Assuming U for the existing accessory building, and the specified B & M I can use the table to determine whether the change in hazard category is higher, lower or equal.
U to a B or an M is higher, therefore we are directed to the IBC, specifically t602. Since the proposed building is non-separated, I would go with M for my determination using IBC t602.
Using M & VB in t602 I see if there is an FSD < 5' then 2-hr ext. walls are required for those portions, and from 5' to 10' then 1-hr. Combustible projections would be 1-hr where within 5' of the FSD per IBC 705.3.2.

You notice an additional building at plan south. This is the other residential accessory structure, a garage no proposed changes, it will remain an accessory to the SFD. IRC 302.1 includes residential accessory structures for compliance with t302.1(1), so if portions of that building are within the table values assigned, those portions would also be required to be rated. And, since the new proposed commercial building is changing from lower to higher in hazard classification the same separation provisions from t602 would apply and the M would need to used in t602.

So my conclusion, based on the above, is the SFD must be protected per IRC t301.2(1) and the commercial building must be protected per IBCt602.

Now it gets uglier. The existing building that they are proposing changing may have been operating as an S1 repair garage, but I have not determined whether it was done so legally (with a permit). If legally, it was certainly not reviewed the way I have layed it out and likely approved in ignorance (likely by one of the town officials so there may be some ass-covering going on). If this is the case, do all of the separation issues from the IEBC go away because now S1 to M is of equal hazard per IEBC t1011.6? And, if this was approved, or is existing, does the house separation go away because it is existing? FWIW, I do not believe the S1 was permitted, but has been tacitly allowed for years...ignorance is bliss.

If it was an S1 repair garage (legally or not) do all of the code provisions get ignored even though they never complied and still don't? This is a bigger question I have had with the IEBC, which I have yet to conclude addresses whether an "existing building" is only existing if it met/meets the code that allowed it to exist.

And to think I offered to do this simple review as a favor........I thought it was just a T/I!

 

[steveray]

To me, once it goes commercial it is all IBC/ IEBC as far as lot FSD stuff....Garage is an S2 house is an R3.....But the wiggle of an "approved" repair garage I would go with if I could find a CO or whatever you need for an approval...

[RB] BUILDING, EXISTING. A building or structure, or portion thereof, erected in whole or in part, for which a legal building permit and a certificate of occupancy has been issued. Buildings or structures or portions thereof erected prior to October 1, 1970 shall be deemed existing buildings regardless of the existence of a legal permit or a certificate of occupancy.

 

[Sifu]

To me, once it goes commercial it is all IBC/ IEBC as far as lot FSD stuff....Garage is an S2 house is an R3.....But the wiggle of an "approved" repair garage I would go with if I could find a CO or whatever you need for an approval...

[RB] BUILDING, EXISTING. A building or structure, or portion thereof, erected in whole or in part, for which a legal building permit and a certificate of occupancy has been issued. Buildings or structures or portions thereof erected prior to October 1, 1970 shall be deemed existing buildings regardless of the existence of a legal permit or a certificate of occupancy.

 

[mtlogcabin]

The distances are measured at right angles to the wall. The SFR and the existing shop building do not require a FSD.

h. For a building containing only a Group U occupancy private garage or carport, the exterior wall shall not be required to have a fire-resistance rating where the fire separation distance is 5 feet (1523 mm) or greater.

Rate the exterior wall portion from both sides of the building with the change of use.

 

[Sifu]

Woops, hit enter too soon. So once commercial use t602 for all separations...seems to be a simpler approach but maybe with the same results.

The definition you provide is from the IRC, not the IEBC or the IBC, which is a mystery and a shame IMHO. I have argued that very point with the "experts". One thing to have been "approved" in error, another to have never been permitted (excluding the really old stuff).

 

[steveray]

Woops, hit enter too soon. So once commercial use t602 for all separations...seems to be a simpler approach but maybe with the same results.

The definition you provide is from the IRC, not the IEBC or the IBC, which is a mystery and a shame IMHO. I have argued that very point with the "experts". One thing to have been "approved" in error, another to have never been permitted (excluding the really old stuff).

Yall just got to fix your Ch. 2 CT IBC and IEBC:

[A] EXISTING BUILDING. A building or structure, or portion thereof, erected in whole or in part, for which a legal building permit and a certificate of occupancy has been issued. Buildings or structures or portions thereof erected prior to October 1, 1970 shall be deemed existing buildings regardless of the existence of a legal permit or a certificate of occupancy.

 

[Sifu]

The distances are measured at right angles to the wall. The SFR and the existing shop building do not require a FSD.

h. For a building containing only a Group U occupancy private garage or carport, the exterior wall shall not be required to have a fire-resistance rating where the fire separation distance is 5 feet (1523 mm) or greater.

Rate the exterior wall portion from both sides of the building with the change of use.

I am puzzled by the idea that there is no FSD required. I guess I imagined an FSD exists, without a requirement that it be there. -That it is one of the three things in the definition that is always there. If so, then if we imagine the line to be half-way, then everything within X feet of the line has to be rated, but if the FSD ends at the building corner, there is nothing in the way of the right angle measurement, so there is no protection required? In the depiction below neither building is required to have rated exterior walls? That would seem to defeat the purpose altogether.


As for the U classification, the proposed new building is not a U so rate that one as required, but the other building is a U private garage so leave it alone? I like that.

 

[steveray]

They have to draw the line first...Unless you want to do all the work:

[BF] FIRE SEPARATION DISTANCE. The distance measured from the building face to one of the following:

1. The closest interior lot line.
2. To the centerline of a street, an alley or public way.
3. To an imaginary line between two buildings on the lot.

The distance shall be measured at right angles from the face of the wall.

It's wall to line not wall to wall...

 

[Yikes]

Can you use 503.1.2 and justify treating all 3 buildings as if they were a single structure? If so, then you're only dealing with an occupancy separation issue, not assumed property lines and . Not sure if that helps with fire ratings or not, just thought I'd throw it out there.

 

[Sifu]

Can you use 503.1.2 and justify treating all 3 buildings as if they were a single structure? If so, then you're only dealing with an occupancy separation issue, not assumed property lines and . Not sure if that helps with fire ratings or not, just thought I'd throw it out there.

Thought of that, but the the residence is not sprinkled so I ruled it out.

 

[Paul Sweet]

Will it work if you consider all 3 buildings as unsprinklered?

 

[Sifu]

Will it work if you consider all 3 buildings as unsprinklered?

Not sure how that could be proposed since the dwelling would require sprinklers under the IBC.

 

[Sifu]

Then there is this?? The house was built under the 2003 IRC, so walls permitted to be unrated if the FSD is 3'. If they assume the 3' FSD between the buildings, the dwelling meets the 2003 code under which it was built. If they make the imaginary line at 4', the walls AND projections meet the 2003. Now, the commercial building is 8" away from the FSD and would follow IBCt602, and the dwelling has no retroactive requirement.

 

[Yankee Chronicler]

All three structures on the site are existing structures. You are incorrect to say "First I deal with the IRC, . . . Second I deal with the IEBC." The IEBC is the starting point for ALL existing buildings. You only go from the IEBC to the IBC or IRC if the IEBC sends you there, and then only to the parts of the IBC or IRC that the IEBC sends you to.

You are dealing with a change of occupancy, so you should start with IEBC chapter 10.

 

[Sifu]

All three structures on the site are existing structures. You are incorrect to say "First I deal with the IRC, . . . Second I deal with the IEBC." The IEBC is the starting point for ALL existing buildings. You only go from the IEBC to the IBC or IRC if the IEBC sends you there, and then only to the parts of the IBC or IRC that the IEBC sends you to.

You are dealing with a change of occupancy, so you should start with IEBC chapter 10.

Not sure I am incorrect, at least in the 2018 codes, and as far as I can tell this has not changed in the '21 or the '24, although the 24 IRC doesn't appear to have been published yet. The problem is the IEBC does not specifically address IRC regulated structures as far as I can tell. The closest would be an IBC R3. The way I see it, I have two separate issues. A) the fire rating of exterior walls of the building that is changing from an IRC regulated structure to an IBC regulated structure (so we definitely use the IEBC) and 2) the affect of the new IBC regulated structure on the existing IRC regulated structure, (which is where I use the IRC). The new idea is to use the 2003 IRC under which the SFD was constructed, which had a lower FSD threshold.

Two things to note:
1) Except for a vague (incorrect?) reference at 110.2 for a change in use, the IRC does not scope the IEBC for alterations (IEBC 507 is for historic buildings, and 508 doesn't exist). It does scope the use of the IRC itself for alterations, and it includes an adoptable appendix for existing structures.
R101.2 Scope. The provisions of this code shall apply to the
construction, alteration, movement, enlargement, replacement,
repair, equipment, use and occupancy, location,
removal and demolition of detached one- and two-family
dwellings and townhouses not more than three stories above
grade plane in height with a separate means of egress and
their accessory structures not more than three stories above
grade plane in height.

2) The IEBC specifically mandates the use of EITHER the IRC or the IEBC for one & two family dwellings. So we can use it, but I really see no specifics for how in this case since the only requirements appear to be for buildings classified by the IBC.
[A] 101.2 Scope. The provisions of the this code shall apply
to the repair, alteration, change of occupancy, addition to
and relocation of existing buildings.
Exception: Detached one- and two-family dwellings and
multiple single-family dwellings (townhouses) not more
than three stories above grade plane in height with a separate
means of egress, and their accessory structures not
more than three stories above grade plane in height, shall
comply with this code or the International Residential
Code.

 

[Yankee Chronicler]

The IRC applies to an existing building ONLY to the extent referenced by the IEBC. The starting point for all existing buildings (if your jurisdiction has adopted the IEBC) is the IEBC:

[A] 101.2 Scope. The provisions of this code shall apply to
the repair, alteration, change of occupancy, addition to and
relocation of existing buildings.
Exception: Detached one- and two-family dwellings and
townhouses not more than three stories above grade plane
in height with a separate means of egress, and their accessory
structures not more than three stories above grade
plane in height, shall comply with this code or the International
Residential Code.

Once you bring in a change of use from a single-family or two-family residence to an IBC-regulated occupancy, then the IEBC provisions for change of occupancy apply.

 

[classicT]

The IRC applies to an existing building ONLY to the extent referenced by the IEBC. The starting point for all existing buildings (if your jurisdiction has adopted the IEBC) is the IEBC:

[A] 101.2 Scope. The provisions of this code shall apply to
the repair, alteration, change of occupancy, addition to and
relocation of existing buildings.
Exception: Detached one- and two-family dwellings and
townhouses not more than three stories above grade plane
in height with a separate means of egress, and their accessory
structures not more than three stories above grade
plane in height, shall comply with this code or the International
Residential Code.

Once you bring in a change of use from a single-family or two-family residence to an IBC-regulated occupancy, then the IEBC provisions for change of occupancy apply.

I generally agree with your point. However, I do not agree that the IRC only applies to existing buildings as scoped by 101.2 of the IEBC.

The IRC has its own scoping that is inclusive of existing buildings. If you fall within the scope of the IRC, the IEBC can be non-applicable, including IEBC Sec. 101.2.

That said, take note that IRC Sec. R101.2 does not include "Change of Occupancy". Change of occupancy will drive towards the IEBC.

2021 IRC R101.2 Scope​

The provisions of this code shall apply to the construction, alteration, movement, enlargement, replacement, repair, equipment, use and occupancy, location, removal and demolition of detached one- and two-family dwellings and townhouses not more than three stories above grade plane in height with a separate means of egress and their accessory structures not more than three stories above grade plane in height.

Exception: The following shall be permitted to be constructed in accordance with this code where provided with an automatic sprinkler system complying with Section P2904:

1. Live/work units located in townhouses and complying with the requirements of Section 508.5 of the International Building Code.
2. Owner-occupied lodging houses with five or fewer guestrooms.
3. A care facility with five or fewer persons receiving custodial care within a dwelling unit.
4. A care facility with five or fewer persons receiving medical care within a dwelling unit.
5. A care facility for five or fewer persons receiving care that are within a single-family dwelling.

 

[Yankee Chronicler]

^^^ Correct, but the IRC doesn't address change of use, because the IRC only regulates one use/occupancy. To find anything addressing change of use, you have to start with the IEBC.

 

[Sifu]

Once you bring in a change of use from a single-family or two-family residence to an IBC-regulated occupancy, then the IEBC provisions for change of occupancy apply.

Agree, but the classification of the SFD is not changing, it was and is still an IRC regulated building. An alteration to it can be administered through the IEBC where specified or the IRC. I just don't see much at all in the IEBC that applies to an IRC regulated SFD. The IEBC is required to be used for an IBC regulated building, whether it was one to begin with, or whether it is being changed to one. That is not the case with the SFD in this thread. The only alterations to it are the ones that could be imposed if the FSD is too close to it, but those would still be alterations, not a change in occupancy and they would be permitted to be administered from the IRC. I am not smart enough to know how to administer them out of the IEBC.

 

[mtlogcabin]

Chapter 5 and alteration levels give you the choice to use the IBC or IRC for the work being done. There is no change of use for the dwelling unit.

 

[Yankee Chronicler]

Chapter 5 and alteration levels give you the choice to use the IBC or IRC for the work being done. There is no change of use for the dwelling unit.

From the original post:

The highlighted structure is being proposed to convert to a commercial establishment, mixed-use, non-separated, B & M.

 

[classicT]

From the original post:

From the OP, clearly shows that it is the shop that is undergoing the change of occupancy.

 

[Yankee Chronicler]

But the shop exists as an accessory structure to a single-family residence. Once it is converted to a commercial purpose (change of occupancy) it is no longer under the IRC, so the starting point is the IEBC, Chapter 10. Then, if any alterations are being made it will have to be determined which method is being followed: prescriptive, work area, or performance.

 

[classicT]

But the shop exists as an accessory structure to a single-family residence. Once it is converted to a commercial purpose (change of occupancy) it is no longer under the IRC, so the starting point is the IEBC, Chapter 10. Then, if any alterations are being made it will have to be determined which method is being followed: prescriptive, work area, or performance.

Correct... but I think you are missing part of the issue here.

The SFD remains a SFD and is still regulated under the IRC. No change of occupancy as it relates to the SFD.

The shop building, originally accessory to the SFD, is being converted to a commercial building; thus, a change of occupancy is occurring.

The question here then revolves around how to calculate FSD for both the commercial and residential buildings. This is difficult given the lack of separating property lines. Imaginary lot lines have to be used. Further complicating the issue is that the IRC under which it was built required a FSD of 3', but it is now 5'.

Placement of the imaginary lot line for purposes of determining the FSD is going to be critically important for this project.

IMHO, I would suggest that the FSD be placed at the mid-point between the structures. As the SFD is not being modified, I would allow it to remain as is, even if the FSD would prohibit openings or would require a rated exterior wall. As for the shop building, which is now commercial, I would ask that it fully comply with the FSD requirements. If the designer proposed to push the imaginary lot line right up to the exterior wall of the SFD, I would push that the SFD comply with the rated exterior wall and opening limitations.