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Trex Deck for balconies on 7 story building

BayPointArchitect

BayPointArchitect

Sawhorse
Joined
Oct 19, 2009
Messages
516
Location
Lincoln
Architect and contractor were asking me if the Trex Deck composite decking material could be used for a small roof top assembly area.

[ note: multiple emergency exits will be provided from roof top = no exit issues ].

I would be okay for use on top of a three story building and limited to a small area.

After giving them an inch, then the architect and contractor take a mile.

They ask if they could use the deck material for several small 4' deep balconies hanging off the side of a 7 story building. Each balcony would serve only one sleeping unit. (Hotel or Apartment = doesn't really matter = R2 occupancy).

The IBC would suggest to me that I could use a Class "C" material if I sprinkle the decks and a Class "B" material if I do not. For a variety of reasons, this will be a sprinkled building and thus the Class "C" material should suffice.

The data sheet for the decking material has fire test results that lead me to believe that this is a Class "C" material.

My fire pit located in my backyard would suggest that the samples provided by the contractor burn just like my particle board and OSB plywood samples. Let's just call that the ASTM 7500 burn test. I was neither impressed or disappointed by the results.

Would Trex Decking be allowed for this application according to your interpretation of the code?

Thanks

Commercial Plan Reviewer

IBC 2009
 
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You might ask this get moved to

Residential building code

Do you have a link to the material
 
You can be "led to believe" what class the material is and I wouldn't accept your determination without proof.
 
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The architect and contractor did not explain what their proposed type of construction would be for the seven (7) story building but I would require either Type IIA (IBC 509.6) or any variation of reinforced concrete, Type IA or IB.

As for the smaller three story building, that type of construction could be combustible Type VB fully sprinkled.

When tested in accordance with ASTM E84, the Trex Wood Polymer Fire Defense Deck Board has a flame-spread index of no greater than 200. ICC-ES evaluation report number (ESR-2387).

How outdoor living should feel | Trex

The following link refers to a burn test that proves that these Trex deck samples provided by the contractor will burn just as well as plywood and particle board samples of equal dimensions.

https://www.dropbox.com/s/5622l5d1vix30oo/BurnTest.AVI
 
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Class of material per ASTM E 84 in Chapter 8 does not apply to flooring materials. Since these are exterior materials applied to a roof in the one case, the flooring requirements of Chapter 8 also would not apply, since it only addresses interior floor finish.

For the roof application, I would consider the decking a roof covering by IBC definition: "The covering applied to the roof deck for weather resistance, fire classification or appearance." Thus, the decking, installed for appearance and other reasons, would have to comply with the appropriate roof covering classification per Table 1505.1.

Since the 7-story building is a Group R-2 occupancy, the type of construction will have to be Type I--no other construction type will allow a 7-story Group R-2 building. Thus, the use of combustible materials in a Type I building must comply with Section 603. Here it gets a little murky, since none of the exceptions address this issue directly. I would consider the roof covering use per No. 4--as mentioned above, if the decking can conform to the requirements of a Class A, B, or C roof covering, then it can be used.
 
cda said:
Trex decking will soften as low as 176 degrees Fahrenheit.
Click to expand...
Many roofing materials will soften when heat is applied (just walk on an SBS modified bitumen roof here in the Phoenix area). The concern is whether the roof covering material will combust and maintain combustion.
 
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