View Full Version : Seperation requirements

Charles Sessums
07-07-2008, 08:11 PM
Jerry, Jerry or others,
Can you walk me through the separation requirements of a mixed use building? My best friend is self contracting a new shop. He is a commercial landscaper. This new building will have storage for pallets of chemicals and all the other stuff a high volume landscape biz will use. This is a red iron building with wood framing. Total sf is about 5k with 1500 of that being office space. The city inspector made a comment but has not handed down a ruling on the fire rating requirement for the wall between the shop and offices. I've dug around in the IBC for awhile and am now turning to you for a bit of help. So help.........please?

Jerry Peck
07-07-2008, 08:34 PM

I depends on what is stored and how much of it.

Go to:

From the IBC.
- - - [F] 307.1 High-hazard Group H. High-hazard Group H occupancy includes, among others, the use of a building or structure, or a portion thereof, that involves the manufacturing, processing, generation or storage of materials that constitute a physical or health hazard in quantities in excess of those allowed in control areas constructed and located as required in Section 414. Hazardous uses are classified in Groups H-1, H-2, H-3, H-4 and H-5 and shall be in accordance with this section, the requirements of Section 415 and the International Fire Code.

From there, it can get complicated.

If the storage area does not fall under Group H, then the storage area might fall under Group S, which has MUCH less stringent separation requirements.

I don't see any matching listing under Group S-2 Low-hazard, and Group S-1 Moderate-hazard does not include anything comparable either that I can see (meaning it likely may fall under Group H-2 or H-3. Which could mean a might require a 3 hour or 4 hour rated wall.

Nonetheless, if it is classified as a Group H occupancy, there are other things which apply in addition to the fire rating of the walls.

Hope that gets you to a starting point. The first thing is to have your friend provide the MSDS sheets on each chemical, then, based on what they say, that will probably lead you to the Occupancy Group, if not, the AHJ will need those MSDS sheets to determine what Occupancy Group it falls under.

Charles Sessums
07-07-2008, 08:44 PM
Thank you Jerry.

That section and table 307.7 is where I stopped. Perhaps that is why the municipal guy has not handed down a edict. To many variables. 6 layers ought to do the trick

Jerry Peck
07-07-2008, 08:58 PM

It's also not just 'what chemicals' but 'how much of what chemicals'.

That's the hard part. If you fall within the limits, you can step down a notch, to be sure, though, go with a 4 hour rated wall.

Also, I doubt you will find a 4 hour rated wall with combustible framing (wood framing). I think the highest rated wood framed wall is only 2 hours. Just adding more 5/8" Type X does not make a wall have a higher fire rating, it just spends extra money for the extra gypsum board and labor to install it.

I'm guessing he will need to use non-combustible framing (metal framing).

Go here: http://www.gypsum.org/pdf/Section%202.pdf (http://www.gypsum.org/pdf/Section%202.pdf) , then go to page 24 of 27 (page 49 in upper right hand corner).

Charles Sessums
07-07-2008, 10:15 PM
I did catch that......qty and what.

The 6 layers was a bit tongue in cheek. He'll just have to wait on the AHJ to make his determination.

Jerry Peck
07-08-2008, 07:49 AM

I knew the 6 layers comment was tongue in cheek, I was only pointing out that, unless it has a UL design number, one could have 10 layers and the wall still not be a "rated" wall.

An example of a 4 hour fire rated wall on the link I posted, on page 24 of 27 (page 49 at the top right), GA file number WP 2945, UL Design U435, shows 1-5/8" metal studs with 4 layers each side, however, everything needs to be attached as specified.

Another example is GA file number WP 2995 on the page 26 of 27, UL Design U490, with 3-1/2" metal studs, however, in this case, the stud gage is specified too - 20 gage, and only 2 layers each side ... each layer being 3/4" instead of 5/8".

There are a multitude of UL designs to chose from, and each has its own specifications which must be adhered to.

Jerry McCarthy
07-08-2008, 08:50 AM
By in large I agree with EC Jerry, but here's my 2 centavos: Under the 2006 IBC it could be an F-1 and/or S-1 (or S-2) with separation from the B occupancy (office)? However, the final call should (will) be by the BO of the local AHJ. As EC Jerry said it will depend what category the items stored will fall under, which again will be the call of the local BO.

Charles Sessums
07-09-2008, 09:19 AM

Thank you for sharing your time and knowledge.