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Fire resistant treated wood

M

Mech

Registered User
Joined
Oct 30, 2009
Messages
1,037
Location
Eastern PA
2009 IBC

Type IIIB construction

Per section 602.3, Fire-retardant-treated-wood framing . . . shall be permitted within exterior wall assemblies of a 2-hour rating or less.

Can I use intumescent paint to transform existing framing into FRTW, or do I need to remove the existing wood and replace with FRTW made in a factory?

Thanks
 
Possibly, under Section 104.11 for alternate materials, design and methods of construction. However, I would have one concern that would need to addressed.

Intumescent coatings, whether for fireproofing (for compliance with ASTM E 119) or paint (for compliance with ASTM E 84) expands when fire causes the coating to char. The charring and expansion of paint applied to stud faces that are eventually concealed by gypsum board may cause pressure between the stud and the gypsum board. This pressure could compromise the integrity of the gypsum board membrane, which is an integral part of the fire-resistant assembly. The pressure may not be great enough to do that, but, if I were the building official, I would like to see some data.

Regardless, you'll need to substantiate the alternative material by providing a research report and possibly test data.
 
2303.2 Fire-retardant-treated wood.

Fire-retardant-treated wood is any wood product which, when impregnated with chemicals by a pressure process or other means during manufacture, shall have, when tested in accordance with ASTM E 84, a listed flame spread index of 25 or less and show no evidence of significant progressive combustion when the test is continued for an additional 20-minute period. In addition, the flame front shall not progress more than 10.5 feet (3200 mm) beyond the centerline of the burners at any time during the test.

I doubt that intumescent paint can comply meet these requirements.
 
FRTW is defined in 2301.1:

Pressure-treated lumber and plywood that exhibit reduced surface-burning characteristics and resist propagation of fire.
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And as referenced from 2303.2:

FRTW...when impregnated with chemicals by a pressure process or other means during manufacture, shall have, when tested...
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Field-applied intumescent paint would not fit within the IBC definition of FRTW. However, I concur with RLGA that an alternative method approach may be an avenue to consider.
 
1. how long will the application last??

2. we like to see documentation that it has been tested in some way

3. we like someone that knows what they are doing to apply it

4. finaly we like to field test it, as burn it!!!!!!! usualy that is where they fail
 
I wouldn't buy this method for a quarter.

I actually just had a report from the inspectors for a new business license and they noted an interior partition wall with gyp on one side and open on the other. They saw standard lumber used in this type 2b buildings partition wall. We have told them to bring it down and rebuild it after they get a permit. Of course they asked what else could be done. I told them to contact an architect. The new solution is to add metal studs next to every 2x6 and call the 2x6 blocking. Not certain I am going to accept this but.....they sure are getting creative, right?
 
Field treated wood is subject to a LOT of scrutiny as you can see. At the very least it would be an alternate method. FRTW is pressure treated so it's not possible to do that in the field. In evaluating the use of any alternate method I'd want to know how much of it is being proposed for this type of method, what the rest of the walls are made of, is the building sprinklered, is the building registered as historic and what sort of fire separation distances are in place.
 
The scenario is an existing building with wooden shims and 2x8 blocking in CMU / storefront window / metal stud walls. The building is too large for Type V and it most likely has wood framed interior walls, disqualifying it from being Type II. There is double 2x8 framing at the top of the windows, one 2x8 at the bottom, and probably some along the sides. No sprinklers, not historic, 20 - 30 ft fire separation.
 
Best thing to do is probably rebuild the 2x8 framing with frt. The blocking and shims are allowed to be used in Type III construction. I don’t have my code with me but I thought it was exception 18 in section 603.
 
Gene: Section 603 is titled "Combustible Material in Type I and II Construction." It didn't address Type III, so I figured that meant no wood blocking, except FRT.

The wood stud walls we are replacing start about 10 feet above finished floor (above the drop ceiling) and end at 16 feet above finished floor.
 
Edit: repeated what was in first post.
 
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David Schnider said:
removed spam linkare the best fire treatment!
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Even if your products "met the code", your withdrawal of the UL listing for them would prevent my jurisdiction from approving their use.

Assuming you don't have a listing from another approved listing agency.
 
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Existing building with existing work? leave alone and/or look at 2009 IEBC ss 720, 721. Further look at 2009 IEBC for work area requirements

New work, remove and install correct material
 
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