Faux Leather and, indeed, vinyls in general have widely varying compositions. So it is very difficult to generalise about FR treatment.
However, as interior designers know, they are great for contract projects because of the excellent abrasion properties and the excellent ease of ongoing care and maintenance. IE they maintain their appearance relatively easily for extended periods.
Contract projects of course pose flammability requirements for the interior designer to determine and specify.
Typically CRIB5 is required for contract upholstery.
Some faux leathers come pre-treated; perhaps containing silicon/Teflon or other substances within the vinyl that limits or excludes the spread of flame required in a crib 5 test.
However some faux leathers require treating. That’s to be expected to a degree as faux leather is a relatively versatile fabric and can be used for a variety of end uses – but hence the required FR treatment will vary.
We recently treated some black faux leather to pass FR for contract curtains. In that case it was possible to treat the back of the fabric (it had a thin absorbent layer on the back) and that was sufficient to stop the spread of flame.
Another brown faux leather that we make has a speciality foam backing, slightly thicker than normal. Whilst this will take the same kind of chemical as the one for curtains the CRIB5 test has a more tricky flame to deal with. Also of consideration is the adhesive required to fix the backing and vinyl together. This adhesive may not be fire resistant again adding to the difficulty of treatment.
The thicker the backer the more luxurious the feel, perhaps. But the more difficult the treatment can be. Some sort of liner / interliner to the rear may well work to stop the flame spreading in a FR test. However, the thicker the foam backing the further away that interliner might be.
We have some specialist backing layers that themselves once set alight release gases (carbon dioxide) that reduce the spread of flame elsewhere. These backing layers do not noticeably add to the thickness of the faux leather.