# How to Determine Construction Type of Existing Building



## fj80

I've been asked to determine the construction type of an existing building. I know Chapter 6 gives explanations of the types, but I'm not sure how to figure out what an existing building qualifies as. I do not have the original building plans.

It's a two-story brick warehouse. It was built in 1981. Footprint is 100'x110'. Exterior walls are brick. Interior bearing walls are concrete block. Floors are concrete slab, possibly hollow-core precast slabs. 

IBC 2015, Maryland

Any thoughts on which construction type it most likely is?


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## cda

So you want to type it under present code??

And not what code it was built to?

what is your guess?


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## mtlogcabin

What is the roof constructed of?


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## fj80

cda said:


> So you want to type it under present code??
> 
> And not what code it was built to?
> 
> what is your guess?


I'm not sure which is more appropriate. The owner is selling the building and the bank wants a letter stating that to the best of the seller's knowledge the existing building meets code. We've been asked to review this for him. I was going to review it under the current code, IBC 2015, figuring that is the more restrictive, and see if it conforms. If not, I could fall back to the original code it was built under.


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## fj80

mtlogcabin said:


> What is the roof constructed of?


Roof is built-up roofing over rigid insulation and steel decking over open web steel joists.


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## RLGA

If nonsprinklered, and assuming the occupancy is Group S-1, then it sounds like Type IIB construction, unless you want to go through the process of determining fire resistance of existing construction per IBC Sections 721 and 722, which could move it to Type VA construction. If there is any unprotected structural steel (i.e., columns or beams) supporting the floor or roof, then it definitely is Type IIB construction.

If the building is sprinklered, then it could be considered Type VB construction based on allowable area.


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## fj80

UPDATE: The owner just delivered a few of the original structural drawings and a complete set of remodel drawings done in 2002. These remodel drawings list the construction type as 2B, non-separated mixed use.
Use groups are S1 Storage and B Business.
It is not fire sprinklered.
The building is divided into four long bays using 12" wide CMU bearing walls.

*Two of the bays have lofts in them built out of standard 2x wood framing that is not fire-protected. Is this code-compliant in a 2B building?*


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## ADAguy

Is the building a "zero" lot line or set back from property lines, if so, how far?


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## fj80

ADAguy said:


> Is the building a "zero" lot line or set back from property lines, if so, how far?


One side is 0.9' from property line. Opposite side (the side facing the street) is 10.1' from property line. Other side is set back 85', and opposite side is set back 90.5'.


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## fj80

And the side that is only 0.9' from the property line has a neighboring building within a couple feet of the property line, for a little more than half of the length of the building I'm studying.


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## RLGA

fj80 said:


> *Two of the bays have lofts in them built out of standard 2x wood framing that is not fire-protected. Is this code-compliant in a 2B building?*



Nope.


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## fj80

RLGA said:


> Nope.


Ok, thank you. And is the relevant code section that tells me it's not code compliant Section 603?


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## fj80

RLGA said:


> Nope.


Also, if Type 2B allows non-bearing interior walls and partitions to have a 0 hour fire-resistance rating, then why would a wood framed loft/mezzanine that's not fire-rated not be allowed? Doesn't the loft qualify as a non-bearing interior wall or partition?


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## RLGA

Type IIB construction only permits noncombustible materials except as permitted by Section 603. If the wood is not not FRTW, then it is not permitted per Section 603. Furthermore, Section 603 does not mention the use of FRTW for floor systems, thus if the wood just happened to be FRTW, it still would not be acceptable because the loft is a floor and the walls supporting the loft are, thus, loadbearing, which further excludes them.


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## fj80

RLGA said:


> Type IIB construction only permits noncombustible materials except as permitted by Section 603. If the wood is not not FRTW, then it is not permitted per Section 603. Furthermore, Section 603 does not mention the use of FRTW for floor systems, thus if the wood just happened to be FRTW, it still would not be acceptable because the loft is a floor and the walls supporting the loft are, thus, loadbearing, which further excludes them.


If I understand this correctly, does this mean that even though, per Table 601, Type 2B building elements have a fire-resistance rating of 0 hours, they still have to be non-combustible materials? That has always confused me. I thought if Table 601 said 0 hours then that means the materials for that category don't have to be fire-rated at all. No?


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## Francis Vineyard

FWIW we have a number of buildings that are 2B but have wood construction within done without permits or documentation.
If haven't done so I suggest contacting the AHJ for the construction type declared in their records or if they will allow you to use the construction type that will work under the current codes.


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## fj80

Francis Vineyard said:


> FWIW we have a number of buildings that are 2B but have wood construction within done without permits or documentation.
> If haven't done so I suggest contacting the AHJ for the construction type declared in their records or if they will allow you to use the construction type that will work under the current codes.


Sorry, but what is FWIW, and AHJ?


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## RLGA

fj80 said:


> If I understand this correctly, does this mean that even though, per Table 601, Type 2B building elements have a fire-resistance rating of 0 hours, they still have to be non-combustible materials? That has always confused me. I thought if Table 601 said 0 hours then that means the materials for that category don't have to be fire-rated at all. No?


See Section 602.2.
Noncombustible does not mean fire-resistant. See Chapter 2 for definitions of "Fire Resistance" and "Fire-Resistance Rating," and Section 703.5 for noncombustibility.


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## fj80

RLGA said:


> See Section 602.2.


Got it, thanks. Sorry for all the questions. This forum rocks.


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## ADAguy

?!  you don't have AHJ's in Virginia (smiling) authority having jurisdiction.
He meant FRTW (fire rated wood)
If loft was installed without permits you have other issues, load rating of loft floor, attachment to exterior walls, etc..


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## fj80

ADAguy said:


> ?!  you don't have AHJ's in Virginia (smiling) authority having jurisdiction.
> He meant FRTW (fire rated wood)
> If loft was installed without permits you have other issues, load rating of loft floor, attachment to exterior walls, etc..


Oh god, we have too many AHJ's then. Hahaha.


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## Francis Vineyard

FWIW: For What It's Worth


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## my250r11

IMO, it sounds like it is a IIIB, non-combustible exterior walls, and any materials on interior, IBC 2015 602.3. The building probably wasn't typed correctly when built or remodeled.


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## RLGA

my250r11 said:


> IMO, it sounds like it is a IIIB, non-combustible exterior walls, and any materials on interior, IBC 2015 602.3. The building probably wasn't typed correctly when built or remodeled.


That's possible, but it will require an analysis of the exterior bearing walls to verify that they are of 2-hour construction--it shouldn't be too difficult, though.


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## my250r11

That was with the thought of being a S-1 and the fire separation from the property line it SHOULD have been 2hr exterior walls.


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## Pcinspector1

fj80, You might also want to read mezzanines section 505 and 505.3 to verify what you have in place meets code. Just saying.


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## RLGA

my250r11 said:


> That was with the thought of being a S-1 and the fire separation from the property line it SHOULD have been 2hr exterior walls.


You're correct. The one wall that has a fire separation distance of less than 5 ft. should be at least a 2-hour wall per Table 602.


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## fj80

my250r11 said:


> IMO, it sounds like it is a IIIB, non-combustible exterior walls, and any materials on interior, IBC 2015 602.3. The building probably wasn't typed correctly when built or remodeled.


The exterior walls are 12" masonry, so I'm pretty sure they're at least 2-hour rated, but I don't see any reason why the building would be IIIB since the original construction and the renovation were both done with non-combustible materials. The combustible wood loft was added sometime more recently, possibly without a permit.


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## ADAguy

What is the property zoning?


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## fj80

Pcinspector1 said:


> fj80, You might also want to read mezzanines section 505 and 505.3 to verify what you have in place meets code. Just saying.


The loft does appear to meet the requirements of a mezzanine, but the problem still remains that it is built of combustible material, so is not compliant with Construction Type IIB.


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## fj80

ADAguy said:


> What is the property zoning?


Zoning is Industrial.


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## fj80

We're considering asking the local code officials if we can get a variance to reclassify the building, or a portion of it, as Construction Type III, so that the existing wood lofts would be code-compliant. But I'm confused about the IBC explanation of Type III construction: "...the interior building elements are of any material permitted by this code." How do I figure out what all the possible building materials are that are permitted by the code. Or more specifically for my case- does that wording mean NON-fire-retardant-treated wood is acceptable?


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## steveray

Anything is allowed inside IIIB....Think laminated chicken fat, cheddar cheese, balsa wood, or your non FRTW, etc...


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## fj80

steveray said:


> Anything is allowed inside IIIB....Think laminated chicken fat, cheddar cheese, balsa wood, or your non FRTW, etc...


Well now I'm just hungry. 
Thanks.


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## my250r11

Here is 2015 602.3 with commentary:
602.3 Type III. Type III construction is that type of construction
in which the exterior walls are of noncombustible materials
and the interior building elements are of any material
permitted by this code. Fire-retardant-treated wood framing
complying with Section 2303.2 shall be permitted within
exterior wall assemblies of a 2-hour rating or less.
 Buildings of Type III construction are typically constructed
with both combustible and noncombustible
materials. The exterior walls are required to be noncombustible
with load-bearing exterior walls required
to have a minimum 2-hour fire-resistance rating.
Exterior nonloadbearing walls are not required by
Table 601 to have a fire-resistance rating, but must
comply with the provisions of Table 602. The elements
within the perimeter established by the exterior
walls (i.e., floors, roofs and walls) are permitted to be
of combustible materials. An example of a typical
building of Type III construction is a structure having
its exterior walls constructed of concrete, masonry or
other approved noncombustible materials, but with a
wood frame floor, interior wall and roof construction
(see Commentary Figure 602.3). The structural members
of a building of Type IIIB construction are not

required to have a fire-resistance rating, with the
exception of the exterior load-bearing walls.
Although fire-retardant-treated wood (FRTW) does
not meet the specifications of the code as a noncombustible
material, it is permitted as a substitute for
noncombustible materials for framing within exterior
wall assemblies of Type III construction. The exterior
surfaces of the walls must be of noncombustible
materials. While the exterior walls are permitted to be
either nonload-bearing or load-bearing, to apply the
allowance for FRTW the required fire-resistance rating
of the exterior wall must be no greater than 2
hours. FRTW is required to comply with the provisions
in Section 2303.2.


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## cda

Airzone said:


> Well, this question is one of those that you can ask a jeweler what my ring is made of. If you are not a master you will never understand what type of construction is used in a building because you are not a builder. I was very interested in architecture and always wanted to work as a Construction Manager, but I went to study to be a doctor. So I did not become a doctor, but I decided to find courses that can teach me the subtleties of their field of construction. I chose Construction Manager Programs, where I found some good information for me to start my career. Maybe I can help you with future questions when I become a professional))



Professional what?


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## Teeshot

So, no construction being performed, built in 1981, so shouldn't the code it was built under be considered for the construction type?


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## cda

Teeshot said:


> So, no construction being performed, built in 1981, so shouldn't the code it was built under be considered for the construction type?



This is an old thread that someone jumped on, maybe an ad?


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