# 2015 IBC plastic composites and allowable construction types



## pleach (Dec 28, 2016)

2015 IBC has a new section regarding plastic composites. Sec 2612.5 states plastic composites shall be permitted to be used as exterior deck boards, stair treads, handrails and guards in buildings of type VB construction. Does this imply that these cannot be used in other types of construction? I have frequently used composite decking on the roofs of multi-family IIIA & VA construction in the past, usually on top of pedestals or sleepers. Is this no longer allowed, or is there another code section I'm missing?


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## cda (Dec 28, 2016)

Welcome

Another Californian 

We have a beach and use to have a peach


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## cda (Dec 28, 2016)

Not the cbc but;;;



*2601.1 Scope. *
These provisions shall govern the materials, design, application, construction and installation of foam plastic, foam plastic insulation, plastic veneer, interior plastic finish and _trim_, light-transmitting plastics and plastic composites, including plastic lumber. See Chapter 14 for requirements for _exterior wall _finish and _trim_.


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## steveray (Dec 29, 2016)

Type V is basically anything so I can't imagine it being prohibited (in theory you could build it out of Sterno)...I would have to look at the requirements for III a little closer, but there are always exceptions for projections and stuff...


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## ADAguy (Dec 29, 2016)

Contrary to what manufacturers say/claim, composites are not wood and as such suffer from solar exposure (color fade, bending, etc.) Are they self extinguishing? Subject to melting?


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## pleach (Dec 29, 2016)

Just found a copy of the code commentary on 2612.5 which says "plastic composites are limited to use on buildings of Type VB construction. This construction type allows for the use of many combustible elements of building construction."

Chapter 14 has a new section on plastic composites towards the end, which just references back to 2612.


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## cda (Dec 29, 2016)

pleach said:


> Just found a copy of the code commentary on 2612.5 which says "plastic composites are limited to use on buildings of Type VB construction. This construction type allows for the use of many combustible elements of building construction."
> 
> Chapter 14 has a new section on plastic composites towards the end, which just references back to 2612.





Check the scope 
Of when chapter 26 applies


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## Francis Vineyard (Dec 29, 2016)

pleach assuming the decking is on the roof and not an exterior wall projection I would recommend using Section 1501.1 (2012 IBC) and other sections in the code that are applicable i.e. Chapter 7.

Postscript: 2015 IBC

*[BF] 1505.1 General. *Roof assemblies shall be divided into the classes defined below. Class A, B and C roof assemblies and roof coverings required to be listed by this section shall be tested in accordance with ASTM E108 or UL 790. In addition, _fire-retardant-treated wood _roof coverings shall be tested in accordance with ASTM D2898. The minimum roof coverings installed on buildings shall comply with Table 1505.1 based on the type of construction of the building.

*Exception: *Skylights and sloped glazing that comply with Chapter 24 or Section 2610.

Commentary: The code designates the use of any particular classification of roof coverings based on the type of construction of the building. A minimum Class B roof covering is required for all roofs that have a minimum 1-hour fire-resistance rating in accordance with Table 602. Roofs without a required fire-resistance rating require a minimum Class C roof covering.




a. Unless otherwise required in accordance with the _International Wildland- Urban Interface Code _or due to the location of the building within a fire district in accordance with Appendix D.
b. Nonclassified roof coverings shall be permitted on buildings of Group R-3 and Group U occupancies, where there is a minimum fire-separation distance of 6 feet measured from the leading edge of the roof.
c. Buildings that are not more than two stories above grade plane and having not more than 6,000 square feet of projected roof area and where there is a minimum 10-foot fire-separation distance from the leading edge of the roof to a lot line on all sides of the building, except for street fronts or public ways, shall be permitted to have roofs of No. 1 cedar or redwood shakes and No. 1 shingles constructed in accordance with Section 1505.7.


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## steveray (Dec 30, 2016)

Ahhhh.....missed the "on roofs" part. Good call FV


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## pleach (Dec 30, 2016)

Thanks for all your input guys, this is the area of the code I'm least familiar with.

So am I understanding this correctly? In 2612.5, where they refer to "exterior deck boards", it's a reference to something like a projecting balcony. But a _rooftop_ deck falls under the Ch 15 provisions for roofs. So if the roof covering meets the classification requirements for that construction type, then you can put whatever material you like on top of that (like sleepers and composite decking).


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## Francis Vineyard (Dec 30, 2016)

Pleach it is my interpretation though the composite decking boards are not technically part of the roof assembly it becomes an integral part of the roof assembly subject to same fire exposure similarly as required for photovoltaic panels referenced in Sections 1505.8 and 1509.9

To my knowledge FRT plastic composite may have a better class rating than C.

http://www.bing.com/images/search?q...+fires&qpvt=photovoltaic+roof+fires&FORM=IGRE


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