Class 25 or Class I or Class A = Flame Spread Ratings 0-25; Class 75 or Class II or Class B - Flame Spread Rating 26-75; Class 200 or Class III or Class C - Flame Spread Rating 76-200; Class IV or Class D = Flame Spread Rating 201-.
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not sure the question but each item is tested and carries its on rating. I do not think you will find a guide.
We looked at two identicaly looking peices of carpet. one had a class a rating and the other did not.