Curious if others interpret the obstructed construction rule the same way I do.

I've seen and heard quite a bit of dispute on how Obstructed Construction should be applied to solid beams with corrugated metal deck above (when applied perpendicular to the beams in question). So the definition of obstructed construction is really defined by applying what unobstructed construction isn't.

In summary, obstructed construction is solid members (or members less than 70% open) that are spaced less than 7-1/2 on center. That would lead you to believe that openings of 29.99% are permitted as long as members are less than 7-1/2' on center.

If you go to the appendix, it offers a LOT more information on types of obstructed construction, one of those being panel construction. There it mentions that (pockets) 300 sqft or less can also be obstructed construction, even with members more than 7-1/2' on center, as long as NO openings are allowed, including at the beam to ceiling interface.

I take this opening rule as only applying to when the 300 sqft exception is being used and where beams are more than 7-1/2' on center. Is this how you interpret this section? 

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I'm designing the fire suppression system for a 6-story wood frame residential building. There will be 6-ft wide balconies made of non- and limited-combustible materials. Normally that would mean sprinklers under the balconies could be omitted, but it occurred to me that people will likely have BBQs and the accompanying propane tank on their balconies.

Would this count as "combustible storage" and thus require sprinklers (dry sidewall heads), or can they still be omitted?

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I always seem to miss listing a pressure gauge on a project. Are any required above what I have in my checklist below?

Sprinkler:

• At each "system riser"
• Before & after backflow preventer
• Before & after any dry or pre-action valve, accelerator, air supply
• At each main drain
• Each side of a pressure reducing or regulating device

Standpipe

• Top of standpipes

Pumps

• Suction
• Discharge

Moderator note: thanks in advance for feedback, we're developing a cheatsheet on this topic in the near future

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I have a multi-story building under a single owner. It consists of a first floor 25,000 sqft area and a second floor, also of 25,000 sqft in area which has a high barrel roof, about 40 ft above the floor.

This second level is unique in that a portion of its area has two levels of rooms, one stacked on the other. Each level is 10,000 sqft in area. To visualize these, consider the first level being individual meeting/office/bathrooms having ceilings and a structure overtop. The second level is of similar area/occupancy/ceiling and is built on top of this lower structure. The architect actually refers to this second level as a mezzanine. The area above the these rooms is open to the high roof. The building is sprinklered throughout per NFPA 13 (2016). A standpipe is not required per IBC 905.3.1.

My position is that the building can be protected as a single zone without floor control valves as it is two stories in height plus a mezzanine under the control of a single owner. Further, the two levels of rooms at Floor 2 are referred in A.8.2.4.1 which gives guidance that 8.2.4.1 is not intending to require floor control valves on small buildings under the supervision of a single owner. Reference NFPA 13 (2016) 8.2.4.1, A.8.2.4.1, 8.2.1, 8.2.2.

Strictly per the standard, are floor control valves required for each level of this building?

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​A special thank you to the top contributors for this past month!

Late thank-you but not unappreciated - thanks for all comments & especially the Top Contributors for March 2021 -

When you have a common office building that is classified as a Light Hazard but you have some rooms that may be Ordinary Hazard such as storage rooms and others.

When you have your layout and one or more of these rooms ends up in your design area, how do you proceed in the calculation?

1.- Do you calculate 0.10 gpm/sqft over 1,500 sqft?

2.- Do you calculate according to Chapter 23 Sections 23.4.4.2.4 and 23.4.4.2.5 specifically for that room even if it is one or two sprinklers?

3.- Do you calculate everything with the density and area for the hazard of that room even though everything else is Light Hazard?

4.- Do you calculate 0.10 gpm/sqft over 1,500 sqft and ensure that the sprinklers inside the room discharge at the minimum density for the hazard they have?

This may be very general and definitely every project is different but every time I run into this I have this same question. I was told to just calculate everything as a Light Hazard but my curiosity always keeps me thinking about it.

Moderator Note: This question is different, but similar to: www.meyerfire.com/daily/ordinary-hazard-within-light-hazard-building

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