Possible defective flame retardant OSB

This is in the attic of a townhouse I looked at this afternoon. As you can see, what appears to be the flame retardant coating on sheathing within 4’ of party walls is flaking off pretty badly. Oddly enough the stuff on the right end of the attic is pretty much intact. Both ends receive equal sunlight and ventilation. Some internet research found no information on this, but the company does have one lawsuit against them for deceptive business practices. Construction Defects | Whitfield Bryson LLP
Have any of you guys seen this before? And, does anyone know of any engineering or other information on this stuff?

Since I need to get this report out tonight I am going to go ahead and recommend investigation by a PE to determine if it will need to be recoated. Since this is in a townhouse I don’t think the HOA is going to be happy. If I am wildly off the mark here please let me know.

The Intertek label is all you need to go by. Warnock Hersey Intertek W/N 14223. 30 Minute Test.

FLAMEDXX® is the first fire retardant OSB on the market. Recommended for roof and wall sheathing, SIPS and flooring, its patented chemical formula helps slow the spread of fire.

My 2 cents. Installation defect. Wrong orientation. Coated side of OBS faces outwards. Cellulose is fire rated.

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The orientation is correct, facing inward.

The coating had failed and with it the sheathing’s fire rating. Very simple.


Simon has it correct. The fire coating/rating has failed and needs correction.


SR provided accurate info
take it to the bank

whenever i’ve encountered that type of fr delamination the direct cause could be traced back to excessive heat/moisture improper ventilation

RY statement is incorrect


Anyone have manufacturers installation instructions?
Well then coating missing on other roof sheathing as well.
Correct. Coated side down.

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WAFI alert # 3,467

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I can’t understand how this so called member, Mark Goldenberg, and awards committee officer to boot, pretends to hold out an olive branch all the while knowing he is not going to keep it.
To be expected.
Roy Cooke senior had the perfect description acronym, and not fowl like Goldenberg’s trash, befitting individuals like Mark Goldenberg. NTBT. Not To Be Trusted.

PS: No information for the thread as well. As/per usual. No wonder not many members follow his quiz. Lol…

Developer of a wood based product designed to advance overlay coating to each OSB panel. The company uses a patented process to apply a fire retardant chemical formula to oriented strand board, protecting families and businesses by slowing the spread of fire and providing an alternative to fire retardant plywood.


Interesting find @mcyr

Now what? Back to the basics I presume, good ol’ gypsum.


Great post Marcel. Much appreciated!

This was what I thought when I first saw it, but then I looked at the other end of the attic just 20’ away and the coating was intact. And, as I said, equal exposure to sunlight and equal ventilation. I wondered if the stuff could have been rained on or gotten wet during construction, then the coating peeled off when it dried.
Here is how I reported it:
The flame retardant coating is flaking off OSB sheathing in the left end of the attic. Flame retardant sheathing is required within 4’ of party walls to slow or help prevent the spread of fire between adjacent units. The concern is that the coating may be compromised sufficiently to reduce the effectiveness of the flame retardant sheathing. Sheathing should be investigated by a NC licensed Professional Engineer to determine what repairs are warranted and repaired according to his recommendations by a qualified contractor.