IBC 2009 modified type 3 construction question

[Mr Softy]

IBC 2009 602.3 allows Fire Retardant Wood to be used in Type 3 construction provided it is encased in a 2 hour exterior wall assembly.

great. no problem. the FTR must conform with 2303.2 (treated at manufacture, not aftermarket).

add a sprinkler system and one can now go 5 stories with wood.

i currently have 3 buildings going 5 stories using this method . the first one is up to the roof in its first phase.

here's the rub.

there are two anomolies in the construction that have got my interest.

1. the connection of the floor trusses to the exterior walls. the top chord of the truss rests on the top plate of the FTR bearing wall. the interior double layer of sheetrock is to be cut around the connection and appropriatley firestopped. my question concerns the non-FTR part of the truss that is now living inside a wall required to be FTR to work as Type 3.

2. the roof truss system is in place. it sits on top of the rated wall. the truss is not manufactured of FTR. it would be my interp that the rating goes to the underside of the roof deck. meaning part of this truss is now encased as part of the exterior wall. Where it is not allowed to be as a requirement of this particular Type 3 constr.

Anyone else have experience with this 5 story Type 3 wood construction? Insights welcome.

if i can recover the pics i took from the iPad, i'll post them.

 

[fatboy]

......................................

 

[steveray]

1. Yes

2. Yes

Knock it down and start over? Derate VB?

 

[north star]

: = :

Is there an RDP associated with this project ?......If so, can

they specify something acceptable to the AHJ [ i.e. - yes,

...aftermarket ]....Possibly some type of ceramic paint

coating with a 2 or 3 hr. fire rating ?....If no RDP, is there

a BO/FCO that you can discuss this with ?

Also, ...were the trusses required to be FRTW treated,

or was this an oversight ?

: = :

 

[Mr Softy]

: = :Is there an RDP associated with this project ?......If so, can

they specify something acceptable to the AHJ [ i.e. - yes,

...aftermarket ]....Possibly some type of ceramic paint

coating with a 2 or 3 hr. fire rating ?....If no RDP, is there

a BO/FCO that you can discuss this with ?

Also, ...were the trusses required to be FRTW treated,

or was this an oversight ?

: = :

RDP - yes

acceptable - they haven't yet. 602.3 is very specific. no aftermarket.

FCO - why?

BO - yes, me.

i think they truly feel the rated wall assembly stops at the 5th floor top plate.

steveray - yes what?

 

[steveray]

i think they truly feel the rated wall assembly stops at the 5th floor top plate.

If they can rate between the plate and truss it does.....I see no way to make #1 compliant, you have non FTW in a wall that should not allow it.....Platform frame "rated" wood construction is a detail nightmare IMHO....

 

[Mr Softy]

unfortunately the roof truss bears directly on the FRT wall.

 

[north star]

= : =

Mr. Softy,

I mentioned the FCO, because they may have some knowledge

or insight as to a solution......Here, when a particular application

called for a 3 hr. fire rated wall assembly, the FCO allowed the

fire rated, ceramic paint to be used, instead of a true 3 hr. rated

[ wall ] assembly........It was not my optimal solution, but it was

what was allowed to be installed, and we moved on.......Thankfully,

to date no fire events have occurred at that particular location to

test it out.

In this AHJ, the Fire Dept. & the Bldg. Dept. have a very good

working relationship, and we regularly discuss a wide range of

applications, ...both "the letter of" and "the intent of" the

codes.

What is the RDP saying in your case ? ...something aftermarket

[ possibly ], ...tear it out and install manufactured FRTW trusses,

other ?

= : =

 

[Mr Softy]

there is an appeal process for the regulated community. i suspect that is where this will wind up.

this is the limit of wood construction, and ICC is very specific about the FRW used. i do not have the authority to approve a compliance alternative on new construction.

that said, do i think an aftermarket treatment would work - yes. will i approve it - no.

 

[Mr Softy]

here's a couple of pics -roof trusses bearing on exterior wall - concealed space is parapet.

View attachment 693

floor trusses bearing (framed into) exterior wallView attachment 694

View attachment 693

View attachment 694

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/monthly_2013_04/572953c72d50b_photo(2).jpg.023f85bc481275b42f044f761b909bf2.jpg

 

[Mr Softy]

btw - this is a residential building (R-2), so i posted it in residential framing.

 

[steveray]

What does the RDP have for an answer?

How did it make it through plan review?

 

[Mr Softy]

meeting scheduled for next week

it wasn't shown - narrative of Wood Type III submitted.

 

[jar546]

btw - this is a residential building (R-2), so i posted it in residential framing.

Yes Sir, I understand that. The codes are being referenced outside of the scope of the IRC and directly referencing the IBC. Sometimes I wish they would clarify some of these things a bit better. Anyway, thank you for bringing this post to the forum and sharing your situation so that we may discuss and learn. Keep it up!