I'm planning to build a house in the northwest in a wooded area and want the high insulation and strength properties of an ICF house but I am concerned that the ICF foam blocks will melt or burn if exposed to the high heat of a forest fire. I could build with concrete or concrete block but I would have to add a second wall to hold insulation. Two walls are not in my budget. Building a wood house would be like asking for it again, been there done that. Is there a fireproof ICF available?

I'd simply go standard ICF and wrap it in brick or stone and a metal-over-concrete roof.

It's about as fire resistant as you're going to get.

Just a quick look found this: https://youtu.be/8MO-3RTF7bw (Bautex).

Thanks for the input. I had always intended to clad the exterior with some fire resistant material but my concern with doing that with the foam ICF is that the foam and plastic webs that the siding would be attached to has a a melting point of around 470 degrees F and radiant temps or open flame in a forest fire would easily far exceed that and everything attached to the ICF would come crashing down. BTW I think the link you sent me answered my question. I wasn't aware that there was a gray block ICF and that it is fireproof. I found a few other manufacturers of gray block closer to me in Arizona and it looks like it's a no brainer alternative to white block ICF.

I've used Durisol/Nexcem in 2 builds. While not fireproof, it has a flame spread rating of 0 and is certainly fire resistant. Insulation is Roxul (now Rockwool), also pretty fireproof.

The block I linked isn't "fireproof".

AFAIK, there is NO such thing as "fireproof" ICF.

Merely that there are varying ratings of fire resistance.

The linked block, when exposed to flame, has a 4 hour burn time rating (which is normal for most ICFs).

And note that, with that type of block, you don't wind up with a solid concrete wall.  You wind up with a concrete honeycomb.

From my understanding, most of the foam used by ICFs contain fire-retardant in it now.

Talk to your local ICF vendors

https://www.icfmag.com/2008/08/fireproof-icfs/


In a fire, you ARE going to have damage.  Either heat-induced or fire-induced.
It's just, with a concrete structure, you're looking at essentially COSMETIC damage unless the burn goes on too long.

Things like keeping your yard, gutters and roof surface clear of debris will cut down on the danger to the structure itself.

And, if you lose the exterior foam, many ICF providers have retrofit panel systems for cases where the exterior insulation is compromised.

http://www.quadlock.com/retrofit_insulation/index.htm


You best bet, however, is to talk to your engineer and/or designer and come up with a strategy for making the house and surrounding area as fire-resistant as you can within your budget.


Also, you're kinda right to worry a little about stone/brick veneer.

I was thinking more in line with an ACTUAL brick exterior.  It's tied back into the webbing  But only with small fasteners every few courses.  So heat transfer (from the middle of a mortar joint) should be minimal.  And more, the brick facing isn't tight to the wall.  There's an air gap in there for moisture release.

Going nuts and doing something like adding an additional layer of rockwool to the exterior probably wouldn't increase the burn time any and wouldn't really help the web-melt problem.

If I remember right, ICF passes code for flame spread but not for smoke.

It's not the walls that will be a problem. It's the roof and windows that will go first.

We build custom homes in wildfire country. Using ICF is as good as it gets for wildfire protection. You also have to consider and do other things.

If you maintain a 150 feet or more clear defensible space around the home, you are at low risk of seeing high temperatures that will damage the ICF EPS. Houses that are in close proximity to each other (i.e., less than 150 feet apart) are very problematic because of the domino effect and it only takes one sloppy clueless neighbor to put the entire development at risk. So you want to build on acreage and you should totally avoid housing developments.

The real risk with wildfires is the blowing brands and embers that can make their way into the attic and crawl spaces. So build slab-on-grade or slab-on-elevated/engineered-grade to avoid having any crawl space. To protect the attic, use metal soffits under the eaves and metal screening in other areas (e.g. roof ridge vent) to keep the embers out. Use a roof (e.g., metal standing seam) and siding (e.g., fiber cement siding with rainscreen airspace between siding and EPS) that is fire resistant. For window protection, you can use roll down metal shutters automatically released by fusible links.

I suspect that a stucco covered block wall with studs on the inside to form a cellulose filled double wall (any R value desired) would be lower cost than ICF + gap + siding. Any crawlspace you build should be sealed, so no concerns about embers.

Posted By jonr on 27 Jan 2018 05:22 PM
I suspect that a stucco covered block wall with studs on the inside to form a cellulose filled double wall would be similar in price to ICF + gap + siding. Any crawlspace you build should be sealed, so no concerns about embers.

The problem I see there is that, generally, things like windows fail first.  Which would then expose your structure.  At which point, you're talking stick construction unless he spends out for the more expensive fire-rated, coated lumber or buying and applying the coating yourself.

http://www.pinkshield.ca/

Why? If the fire is that intense, the building is going to be destroyed and need replacing. The fact you chose concrete walls is good, it gives you more time to escape the fire, life is priority over the structure. The fires that recently went through Napa/Sonoma, ICF house I built, only the walls stayed standing, everything else is gone, now FEMA took the rest down and they can completely start over.

I am curious if this Napa/Sonoma ICF home was in a housing development, had 150 feet of defensible space, had fire resistant roof and siding, had window fire protection or had any wooden structures nearby such as wooden decks, etc. Do you happen to know if any ICF homes survived this disaster? Thinking there should be some good data from this event that we can learn from.

Here's a good house ember storm testing video:

IBHS Research Center Ember Storm Test Highlights

Composite ICFs. One of them had a photo ad of a flame being held to a piece. They are mostly available in the US SouthWest.

Borst - it was a winery almost at the top of atlas peak, no fireproof roof or windows - as very few ICF houses do not go to this extreme. No nearby structures,

You can also finish roof with ICF forms that will take care a fire problem on your roof, finish all walls with stone or brick and add metal shutters to all your windows , keep the woods from the house at minimum 30 yards

If roof and windows are adequately protected, it seems one option to protect foam block behind stone or fiber-cement cladding might be a continuous exterior insulation layer of roxul comfort board. An inch or two would provide an nice additional layer of insulation and fire protection without overcomplicating install.