Wood substitute for low budget paneling

[BillConnerFASTC]

Mud and muslin usually does it. I don't think just foam coat. But when does it make sense to just use 1 x 4s? I'll try to find more but travelling at the moment.

 

[teqniqal]

What about when completely covered by Rosco FoamCoat or equivalent product? I know the code reference Bill mentioned basically just says, "Don't use foam..." without any exceptions, but it seems like there are a number of ways it could be done with a reasonable level of safety.

I rarely see 'completely covered'. It's usually just the audience -facing part of a prop or scenery. People don't care abut painting the backside of stuff because they are generally not thinking about Fire Safety, just aesthetics.

I'll leave 'reasonable level of safety' up to the AHJ and a jury.

As to the effectiveness of the Rosco FoamCoat, I'd contact Rosco and see what they say 'in writing'.

 

[Colin]

Rosco will provide an E84 certificate for FoamCoat and FlexCoat. That's testing performed with a 5/8 gypsum board substrate, not foam. It's also a 1/8" +- 1/32" troweled on coating. Rosco's language in the product descriptions only states that the product itself is flame retardant. Nevertheless, applied at the tested thickness or greater it satisfies me and also my fire marshal (as we look up at the sprinklers and smoke vents). As teqniqal points out, it's hard to reliably achieve or enforce a minimum thickness. And most critically, Rosco doesn't document a test of the common application over EPS foam. What would that even look like? We introduce too many variables from instance to instance the way we use the products - not like the simplicity of code framing, insulation, drywall.

I've field tested some samples with FoamCoat that did well and lots that didn't. I'm pleased that all the ones prepared by me went well, but still troubling how careful one has to be in application. Flame seems to find any tiny weakness in the coating and then the foam melts, enlarging the breach until it can get a flame going. It's a delicate flame at first - pretty easy to blow out or self-smother (what seems to have happened in the youtube clip above) but if it gets going, which will happen on a vertical surface more than horizontal (youtube clip, I think?), then it's lots of flame and gross dark smoke really fast. A 4x8 flat with a little 3/4" thick trim probably just trips a sensor and fizzles without spreading a fire. A whole Les Mis bridge, etc... different - the size of the "fuel package" can matter, including AHJ-wise. Less than 1 pound in close proximity and they aren't concerned with FR treatment in my locale.

This issue is a big thing in "real" building too. There are games being played with E84 and 814 tests on nonflammable substrates being used to justify very different applications - the orange "fireblock" marketed spray foams... Builders and manufacturers are both doing it. Energy efficiency is nice but some inspectors are deciding there's still a place for mineral wool if you don't want things to burn down.

 

[JonCarter]

How far away from this 'paneling' is your audience? If more than about 30', just have your painter paint it on ordinary flats. Any scene painter worth his/her salt should be able to give you what you need.

 

[Malabaristo]

Mud and muslin usually does it. I don't think just foam coat. But when does it make sense to just use 1 x 4s? I'll try to find more but travelling at the moment.

Yup, I was thinking more of the normal use for foam in complex, textured surfaces. It's pretty clearly not the best choice for this specific application: by the time you add an appropriate coating, you probably would lose the clean lines you were going for, and add a whole lot of labor and other expense.

 

[Van]

What about when completely covered by Rosco FoamCoat or equivalent product? I know the code reference Bill mentioned basically just says, "Don't use foam..." without any exceptions, but it seems like there are a number of ways it could be done with a reasonable level of safety.

What 'Code reference' is that?

 

[Malabaristo]

I was going off of memory, so there's a little more nuance to it: NFPA 101 13.4.6.11.2 says that the foam itself must meet a certain fuel load requirement (<100kW) based on NFPA 289 testing. So, technically you could be allowed a certain quantity of foam if you can get that information*, but what stuck in my head as "don't use it at all" is that there's no allowance for NFPA 701 testing the way there is for other combustible materials. To me that says the rule doesn't consider surface treatment as a mitigating factor.


*I took a quick look at Owens Corning Foamular specs as an example and they do not list NFPA 289 info in their UL reports. Maybe others do or could provide it on request...

 

[Colin]

If your jurisdiction uses the IBC then turn to chapter 26. Read the full text, but my non-guaranteed summary is that foam needs to be separated from an interior space by a thermal barrier like 1/2" or thicker drywall, or heavy timber, or 1"+ masonry/concrete. If the interior space is accessible but not used for living or storage (attic/crawlspace, but probably not ever scenic applications) then the lesser requirements of an ignition barrier apply. There are exceptions which can apply in some cases, such as for interior trim made from foam, but the requirements of the exceptions are pretty restrictive - I recall 1/2" max thickness, 8" max width, not more than 10% total surface area of the wall covered.

There's more - worth reading yourselves.

Edit: Also, in NFPA 1 20.1.2.2 you'll find language about allowable fuel packages for foam in assembly occupancies, which leads you to NFPA 289 testing, which leads you to research whether foam insulation makers have done that test. I haven't ever found evidence that they have - why would they when their products are intended to be behind thermal barriers, not used as decoration... But also, 20.1.2.2 allows AHJ to make a ruling instead.

 

[BillConnerFASTC]

What I found is the foam that is tested are specific objects - like a wig block or specific decorative item -not "raw" material. Sorry I haven't pasted code yet - will do. Need a few minutes at my desk.....

 

[BillConnerFASTC]

Here is Life Safety Code on foam scenery:

The International Fire Code, which is the International Building Codes fire regs after substantial completion, says:

807.5.1.1 Foam plastics. Exposed foam plastic materials and unprotected materials containing foam plastic used for decorative purposes or stage scenery or exhibit
booths shall have a maximum heat release rate of 100 kW when tested in accordance with UL 1975, or when tested in accordance with NFPA 289 using the 20 kW ignition source.

Exceptions:
1. Individual foam plastic items or items containing foam plastic where the foam plastic does not exceed 1 pound (0.45 kg) in weight.
2. Cellular or foam plastic shall be allowed for trim in accordance with Section 804.2.

As I noted above, NFPA 289 is to test an object, like a chair or mannequin, not a building material to be used in any quantity you imagine. My opinion is it's very hard to use foam - XPS like the pink or blue stuff - in scenery.

 

[garyvp]

You might consider painting if using a graining tool. Also look at faux wood finishes at YouTube.

I agree - youtube all the way. I have done several projects with graining techniques and its fast and looks real. I stopped buying paneling. And, you can add fire retardant to the paint. I did a small set this summer where they would not allow foam set pieces without a FDNY certificate, but had no problem with a painted wall that had been treated.