Atrium in existing 2 story building

[feb5007]

Working on a small medical office renovation (Class B, type IIB construction). The office is two stories, each being around 2,000sf (below sprinkler requirement). The existing building is not sprinklered, but the lobby/entrance/waiting area is. The waiting area has a 2 story atrium space, there is no stair within it (stair is located elsewhere), but it opens up to Level 2 with a railing separation. Looking at Section 404.3 it states that the area of a building adjacent or above the atrium need not be sprinklered provided that portion of the building is separated from the atrium portion by not less than 2-hour fire barrier. The way the walls for the two levels layout we need to go through hoops to continue the rating up to roof deck.

Looking at 712.1.9 (5), it states that a vertical opening connecting 2 stories is permitted if it isn't open to a corridor on non-sprinklered floors, but looking at this I am not sure if this applies to us. As mentioned above the area around the atrium is sprinklered, but the rest of the floor is not sprinklered. The non-sprinklered area is separated by a wall/door, not sure what rating. Without knowing this is that enough, or would we need to go by 404 and add the 2 hour fire barrier?

 

[RLGA]

I assume you mean "Group B" as in occupancy classification instead of "Class B," unless you are referring to some real estate, BOMA, etc., building classification system.

Has the jurisdiction adopted the IEBC? If so, any condition that previously existed legally may continue unless specifically addressed by the IEBC, IFC, or IPMC (IEBC Section 101.4.2). If the IEBC is adopted, use the prescriptive compliance method, which has no trigger provision for alterations requiring a sprinkler system throughout the building. Otherwise, if you use the work area compliance method, Level 2 Alterations would require a sprinkler throughout the building if the work area exceeds 50% of the floor area. If the renovation is considered a Level 3 Alteration, then a sprinkler system would be required throughout, regardless.

If no work is performed in the atrium, and the office areas will continue to be office areas (not a change of occupancy), then I see no reason for compliance with IBC Section 404. Regarding Section 712.1.9, item 5, if there are no corridors within either story in the office areas, then compliance with this would be deemed affirmed. If there are corridors, then your only option is to call it an atrium.

IFC Section 1103.4.4 requires buildings with atriums to be sprinkled throughout or separated with 1-hour fire-resistance-rated construction. If the walls between the atrium and the office areas have 5/8-inch Type X gypsum board, you should be able to consider that as 1-hour construction. You might have to change openings in the walls--look to see if the doors and frames have labels. If the doors are rated, then it is likely that the wall construction is also rated.

 

[Sifu]

If so, any condition that previously existed legally

RLGA, I am interested in your thoughts here. I have a long standing debate about this statement. What does legally mean? Is it legal if it was approved in error? Or does legal mean "met the code" under which it was constructed? Do we disregard violations because a previous building official either missed it, or decided to allow it based on some unknown circumstance, or the element was altered without a permit and is not code compliant?

If this is too off-topic from the OP I apologize.

 

[RLGA]

RLGA, I am interested in your thoughts here. I have a long standing debate about this statement. What does legally mean? Is it legal if it was approved in error? Or does legal mean "met the code" under which it was constructed? Do we disregard violations because a previous building official either missed it, or decided to allow it based on some unknown circumstance, or the element was altered without a permit and is not code compliant?

If this is too off-topic from the OP I apologize.

I would say that if a certificate of occupancy was issued, it would make it a legal occupancy.

 

[feb5007]

I assume you mean "Group B" as in occupancy classification instead of "Class B," unless you are referring to some real estate, BOMA, etc., building classification system.

Has the jurisdiction adopted the IEBC? If so, any condition that previously existed legally may continue unless specifically addressed by the IEBC, IFC, or IPMC (IEBC Section 101.4.2). If the IEBC is adopted, use the prescriptive compliance method, which has no trigger provision for alterations requiring a sprinkler system throughout the building. Otherwise, if you use the work area compliance method, Level 2 Alterations would require a sprinkler throughout the building if the work area exceeds 50% of the floor area. If the renovation is considered a Level 3 Alteration, then a sprinkler system would be required throughout, regardless.

If no work is performed in the atrium, and the office areas will continue to be office areas (not a change of occupancy), then I see no reason for compliance with IBC Section 404. Regarding Section 712.1.9, item 5, if there are no corridors within either story in the office areas, then compliance with this would be deemed affirmed. If there are corridors, then your only option is to call it an atrium.

IFC Section 1103.4.4 requires buildings with atriums to be sprinkled throughout or separated with 1-hour fire-resistance-rated construction. If the walls between the atrium and the office areas have 5/8-inch Type X gypsum board, you should be able to consider that as 1-hour construction. You might have to change openings in the walls--look to see if the doors and frames have labels. If the doors are rated, then it is likely that the wall construction is also rated.

Thanks RLGA. Yes Group B. The jurisdiction has adopted IEBC and this is a Level 3 Alteration. I mistyped in my original question, this is type IIIB construction, so even though it falls way below the IIIB non-sprinkler area and height requirements in IBC 2018, we would still need to sprinkler the whole building because it's a Level 3 Alternation in IEBC 2018?

Also, I am a bit confused on whether we need a 2 hour fire barrier or a 1 hour fire barrier. As you mentioned above, IFC Section 1103.4.4 requires a 1-hour fire-resistance rated separation, but IBC Section 404.3 states that an approved automatic sprinkler system needs to be installed throughout, with exception 1 that states that the area of a building adjacent or above the atrium need not be sprinklered provided that portion of the building is separated from the atrium portion by not less than 2-hour fire barriers constructed in accordance with section 707.

I guess, all in all, I am uncertain on if the whole building needs to be sprinklered (have heard both) and if it is not if the atrium needs to be separated by 2 hour or 1 hour fire barrier.

 

[RLGA]

Thanks RLGA. Yes Group B. The jurisdiction has adopted IEBC and this is a Level 3 Alteration. I mistyped in my original question, this is type IIIB construction, so even though it falls way below the IIIB non-sprinkler area and height requirements in IBC 2018, we would still need to sprinkler the whole building because it's a Level 3 Alternation in IEBC 2018?

Also, I am a bit confused on whether we need a 2 hour fire barrier or a 1 hour fire barrier. As you mentioned above, IFC Section 1103.4.4 requires a 1-hour fire-resistance rated separation, but IBC Section 404.3 states that an approved automatic sprinkler system needs to be installed throughout, with exception 1 that states that the area of a building adjacent or above the atrium need not be sprinklered provided that portion of the building is separated from the atrium portion by not less than 2-hour fire barriers constructed in accordance with section 707.

I guess, all in all, I am uncertain on if the whole building needs to be sprinklered (have heard both) and if it is not if the atrium needs to be separated by 2 hour or 1 hour fire barrier.

Just because a space looks, walks, and quacks like an atrium does not mean it is an atrium. If the two-story opening can be considered something other than an atrium per Section 712, then Section 404 does not factor into the issue. As a matter of fact, Section 404 should not factor into the situation at all, because nothing in the IEBC will send you to IBC Section 404. However, the IFC does require 1-hour separation if it is an atrium. if the two-story opening can be considered anything other than an atrium, no separation or sprinkler system is required.