combustible roof deck - intumescent paint 1

[pipesnpumps]

Reviewing plans where sprinklers were omitted from an attic space. Metal truss with exposed OSB roof deck (topped with standing seam metal roof). They called for the exposed side of roof deck to be painted with intumescent paint. However, unless I am mistaken the following says that doesn't meet the exception, and thus this attic requires sprinklers.

NFPA 13-2010
"8.15.1.2.11* Concealed spaces in which the exposed materials are constructed entirely of fire retardant–treated wood as defined by NFPA 703, Standard for Fire Retardant–Treated Wood and Fire-Retardant Coatings for Building Materials, shall not require sprinkler protection."

"A.8.15.1.2.11 The allowance to omit sprinklers for fire retardant–treated wood requires a pressure-treated application. It does not apply to coated applications."



Anyone disagree with that interpretation? if so, then why. I won't debate the merits of it, just want a reasonable 2nd opinion on interpretation as there is money and legal implications.


Real world knowledge doesn't fall out of the sky on a parachute, but rather is gained in small increments during moments of panic or curiosity.

 

[stookeyfpe]

P&P

I would agree that from the perspective of NFPA 13 that an intumescent does not equal FRTW. Coatings may not provide complete coverage when they are applied.

The IBC does permit intumescent coatings in Type II buildings (which your roof structure appears to meet), provided they have the required fire-resistance. In the 2009 IBC these coatings are subject to Special Inspections per Section 1704.13. Your selected coating could be used in lieu of FRTW for compliance with the IBC.

 

[pipesnpumps]

They state the intumescent coating meets ASTM E84, and therefore the 8.15.1.2.10 exception applies.

What are your thoughts on that?



8.15.1.2.10 Concealed spaces where rigid materials are used
and the exposed surfaces have a flame spread index of 25 or
less, and the materials have been demonstrated not to propagate
fire more than 10.5 ft (3.2 m) when tested in accordance
withASTM E 84, Standard Test Method of Surface Burning Characteristics of Building Materials, or ANSI/UL 723, Standard for Test for Surface Burning Characteristics of Building Materials, extended for an additional 20 minutes in the form in which they are installed, shall not require sprinkler protection.


Real world knowledge doesn't fall out of the sky on a parachute, but rather is gained in small increments during moments of panic or curiosity.

 

[chevy4x4trucks]

It would be similiar to covering the bottom side of the wood with gypsum board which is done frequently to cover combustibles.

 

[stookeyfpe]

P&P

It sounds like the material would meet the requirement of Section 8.15.1.2.10. My concerns are:

1) What's the service life of the coating?
2) Any unique listing limitations, i.e., temperature, substrate preparation?
3) Who verifies the coating was properly mixed (if it's a mixture) or that the required thickness/coverage is met?

I'm still concerned as to how this would work in the context of the IBC. I understand that's not your concern.

 

[pipesnpumps]

I am still skeptical also, but got a greenlight from the official AHJ in D.C., who agreed they are meeting 8.15.1.2.10. Also this is a type VB building, so the coating is just to satisfy NFPA 13.

A weird wrinkle is the contractor used non-FRT wood only because our fire "code", UFC 3-600-01, disallows FRT wood (pressure treated) as part of the roof structure.. Since he needed a nailing surface for the fancy "tin" roof he was forced to use non-treated wood and coat with intumescent paint.

Thanks for the input.

Real world knowledge doesn't fall out of the sky on a parachute, but rather is gained in small increments during moments of panic or curiosity.

 

[pipesnpumps]

Should have read "UFC 3-600-01, disallows FRT PLYWOOD (pressure treated) as part of the roof SYSTEM"

Real world knowledge doesn't fall out of the sky on a parachute, but rather is gained in small increments during moments of panic or curiosity.