Existing Building - Parapet Construction

[MAGB]

I have an adaptive reuse project where the building is located 4'-5" from the property. The glu-lam roof structure is exposed inside and it is important to the client to keep it that way. The Glulam tails and roof overhang extend past the exterior wall in question to the property line.

We are proposing a change of use from an S-2 (it was a firehouse engine room) to an A-2 (brewpub). Per the IEBC, the new occupancy is of a higher hazard category so should meet the exterior wall requirements, in which case the overhang/eave would need to be cut back and we would also need to somehow meet the parapet requirements with either a class B roof, or fire-rating the framing elements to a minimum 1-hour rating.

There is an exception to meeting the exterior wall requirements in the IEBC:
Exception: A 2-hour fire-resistance rating shall be allowed where the building does not exceed three stories in height and is classified as one of the following groups: A-2 and A-3 with and occupant load of less than 300, B, F, M or S.
The project meets the criteria for the exception. The existing exterior wall is double whythe masonry with a 4" cavity solid grouted with concrete. There are no openings in this wall. So by prescriptive fire-resistance definitions it is well beyond 2 hours. Would this be sufficient, or do I need to be creating a 2-hour fire wall, which starts to look more like the parapet requirements? I am trying to avoid butchering this lovely old building as well as keep costs under control. The building is fully sprinklered.

 

[classicT]

I'd reach out to the AHJ sooner than later to get their opinion; especially when it comes to the IEBC.

Word to the wise, stop calling it a fire wall. It is a fire-resistance rated exterior wall.

 

[cda]

Welcome

Plus I take it, this is all existing???

You are not adding the “tails??

 

[RLGA]

Is the wall 4'-5" from the property line or the edge of the overhang? If it's the distance of the wall, how far does the overhang extend beyond the wall?

 

[MAGB]

Everything is existing there is no exterior work. There is a change in occupancy in the trigger.
The building face is 4'-5" from the property line. The overhang extends beyond the building face to the property line.

 

[cda]

Seems like you can use it as is, as long as not adding on that side???

 

[RLGA]

I'm assuming the 2015 IEBC is applicable, but I don't think the other editions will be much different.

Use the prescriptive compliance method--it is much simpler and easier to follow. In this case the applicable section is 407 for change of occupancy.

Section 407.1 states in part, "Changes in use or occupancy in a building or portion thereof shall be such that the existing building is no less complying with the provisions of this code than the existing building or structure was prior to the change."

The requirements for parapets and projections are not conditional based on the occupancy group; thus, no matter what occupancy group is in the building, the requirements for parapets and projections are the same. Therefore, changing the building from a Group S-2 to a Group A-2 does not make the building any less compliant than it was prior to the change; hence, the exterior wall and overhang conditions can remain as they currently exist.

 

[steveray]

Talk to the AHJ.....

SECTION 407
CHANGE OF OCCUPANCY
407.1 Conformance. No change shall be made in the use or
occupancy of any building unless such building is made to
comply with the requirements of the International Building
Code for the use or occupancy. Changes in use or occupancy
in a building or portion thereof shall be such that the existing
building is no less complying with the provisions of this code
than the existing building or structure was prior to the change.
Subject to the approval of the building official, the use or
occupancy of existing buildings shall be permitted to be
changed and the building is allowed to be occupied for purposes
in other groups without conforming to all of the
requirements of this code for those groups, provided the new
or proposed use is less hazardous, based on life and fire risk,
than the existing use.

 

[MAGB]

Thank you all for your replies.
We are under 2018 IEBC/IBC

My take is from IEBC 1011 Change of Occupancy Classification

1011.6.1. Exterior wall rating for change of occupancy classification to a higher hazard category.
Where a change of occupancy classification is made to a higher hazard category (...) exterior walls shall have a fire resistance and exterior opening protectives as required by the IBC.
Exception: A 2-hour fire-resistance rating shall be allowed where the building does not exceed three stories in height and is classified as one of the following groups, A-2 and A-3 with an occupant load of less than 300, B, F, M or S.​

I believe we would qualify for the exception since the exterior wall is prescriptively 2+ hours and we are changing to an A-2 occupancy of under 300. But the exception isn't totally clear about the extents of the 2-hour fire resistance rating.

Following that I would then take it that this would cover all requirements that fall under IBC 705 Exterior Walls, which includes the parapet and overhand requirements.

 

[MAGB]

In the 2018 prescriptive requirements for change of occupancy are in 506 there is a similar statement to 407.1 posted above, I see that one could argue by this method that the non-compliant condition is no less complying that the previous since the parapet and overhang requirement are not tied to use in the IBC.

I think at this point I then have two arguments to maintain the existing condition without modification, the prescriptive compliance as well as the exterior wall exception.

 

[steveray]

I would agree with the exterior wall exception, not the "no less complying" as it is a more hazardous use....The end result may be the same, but you would have to go work area which could have other complications...

 

[RLGA]

I would agree with the exterior wall exception, not the "no less complying" as it is a more hazardous use....The end result may be the same, but you would have to go work area which could have other complications...

Let me put it this way, would a new Group A-2 building have different projection requirements than a new Group S-2 building? The answer is no, because the projection requirements in the IBC are the same regardless of what is inside the building—the IBC does not take into consideration the relative hazard of the occupancy when it comes to projections.

The existing building has a noncomplying projection. When the occupancy group is changed, the existing building still has a noncomplying projection. By changing the occupancy, the application of the projection requirements of the IBC have not changed; thus, the existing condition is no less complying than it was prior to the change of occupancy. If the IBC had different (i.e., more restrictive) projection requirements for Group A-2 than it did for Group S-2, then it would be a different story.

 

[steveray]

Good argument Ron, I just don't see it unless the BO buys it....If you are going prescriptive...