I am hoping to finally make it past the planning commission and build my 30'x50' (zoning maximum) welding shop  (Only six years and four plans submitted so far...).  This is in a Scenic Area in which as many trees as possible are required to remain on the site.  I am surrounded by Oregon White Oak and Ponderosa pine (as well as poison oak, ticks, and mosquitoes - but only the poison oak contributes significantly to the fuel load) and it is a matter of when, not if, a wild fire will sweep up the slope and engulf my building area.  I am planning on a green roof (about 4" of growing medium with lots of sedums) on a 1:12 slope.  I assume the green roof will moderate temperatures and ward off most firebrands,  but I would still like a roof system that will stand up to the worst case scenario. 

From what I have been able to find out, wildland fires can generate temperatures up to 2000 degrees F.  It has been reported that typically, the frame front of a wildfire remains over one spot for only about a minute or slightly more.  Still there is enough radiation heat and direct flame contact to char wood. 

I have already put down a deposit on a steel frame building (without a roof or walls) from a local supplier.  The scenic area zoning prohibits steel roofs (someone on a scenic outlook might happen to catch a glint of reflection from even a painted steel roof) which is all that the local vendor supplies.  A green roof should allow for lower summer temperatures inside the shop without resorting to air conditioning (I can handle up to 100 degrees F with surprisingly little sweat in this low humidity environment).  A SIP with some additional insulating qualities looks very attractive as the roof structure.  To span from wall to roof peak would require a SIP with a 16' clear span, although purlins could be added at whatever spacing is best.  The county requirement for snow load is 25 lb/sq.ft. and I am figuring on another 25 lb./sq.ft. loading from the membranes, root guards, light weight growing medium, and other elements of the green roof.  (Also: Wind:  100 mph., Seismic Zone C, Exposure 2C)  The building will be considered "partially insulated" so does not have a specific insulation requirement.

From my reading, it appears that commercial construction often uses polyiso insulation for enhanced fire protection.  My concern with EPS and XPS is their 240 degree C melting point.  While it would appear that a roof SIP utilizing EPS might protect the interior of a shop even in a bad wild land fire, I would assume that at least at the eaves the EPS would be above its melting point in the worst case scenario.  If that were the case, I would assume that the SIPS and the green roof would have to be replaced. 

I have spent several hours looking at SIP websites.  I only found one site, GEFCO, LLC that clearly spelled out that they had SIP roof panels with steel cladding.  There were a couple of other sites that were not too clear on whether they actually provided steel sips with polyiso centers.  Several suppliers provide polyiso with OSB skins.  Unfortunately, GEFCO, LLC is in Florida which means were I buy from them, I would have to pay a hefty shipping charge as well as having my carbon budget in hock for centuries (with several trucks, it is not in too good of shape as is...)

Does anyone know of other suppliers of steel skinned SIPS with polyiso?  Preferrably on the West Coast closer to Oregon.  Does anyone have a better (i.e. more fire resistant and/or less expensive) solution to the situation?  I really am not a fan of OSB, having some of it badly swell from water penetration.  If the membrane under the green roof were to leak, I could imagine the OSB deteriorating.  And if there were overhangs as the design currently calls for, additional steps would have to taken to protect these areas.  However, I am open to suggestions and/or arguments.

My building site is on the Columbia River 70 some miles east of Portland, Oregon.  This is in the Columbia River Gorge Scenic Area. 

Whew, think that covers it - or should I write a couple of more chapters on the subject? 

Thanks, Casey

CaseyR;

try metalspan, while they have poor span capabilities, you are going over a rediron frame anyway

http://www.metlspan.com/

2000 degrees is a tall order, even steel will twist and warp at those extremes

Thanks Chris, I figured you might come through for me.  I wouldn't expect a building to escape unharmed if it actually was subjected to 2000 degrees.  In looking at the burn pattern of past fires in the area, the relatively high winds that are common in the area (this is one of the top wind surfing areas in the country) has kept the fires moving and skipping around so that there were very few areas that were completely obliterated.  Standard steel sheathed EPS would probably survive in most instances, but as a "belt and suspender" kind of guy, I figured why not try and set a model for fire resistance to this type of fire hazard.  If you can list any others that are a cut above the norm as far as fire resistance goes, I would like to look at them.

I had originally thought about building a light gauge steel framed building until I thought about the fact that steel will often perform worse in a fire than wood framing.  In many instances, a 6"x8" or larger wooden beam can be considered fire resistant (with proper loading) whereas typical light gauge steel would look like spaghetti in a moderately severe building fire.  The main reason for the desire for steel skins is that I don't trust OSB if it were to get wet from a problem with the membrane under the green roof.  I really have not looked into how OSB as a sheathing would compare to steel in fire. 

If you have run across any studies of what actually happens to an EPS SIP when exposed to wildfires, I would appreciate any references.   It has surprised me how little attention people pay to fire resistance when they choose the materials for their
homes. 

Are you at all familiar with a product called "Agriboard".   I searched on a couple of GreenBuildingTalk forums but got no hits.  They claim it has a 2.5hr fire rating and is made from compressed agricultural fiber.  Unfortunately, they don't give enough information on their website to full evaluate the product. 
http://www.agriboard.com/

Thanks, Casey

Casey;

I checked out Agriboards site , looks complicated,

I did not see the 2-1/2 hr claim

I think in a wild fire area the concern should be first for resistance to hot embers, second to extreme heat, but I don't beleive you will find anything to withstand being surrounded by wildfire, if you watch the news , fire equipment caught in the flames are reduced to a lump of steel

Casey, the panels sold by GEFCO LLC are made by Kingspan, which has manufacturing facilities in several locations throughout the world (California for example). You could likely find a distributor near you. Kingspan do not call the panels "SIPS" so if you do a search that way they won't come up. They are the same as structural steel SIPs, but you will need to have your plans engineered.

Jelly, thanks.  There is a distributor in Vancouver, Washington which is less than 100 miles from my building site.

Chris - The fire rating claim is made under the "Low-Rise Commercial" tab as follows:

• installs quickly on site with no job site waste, saving up to 4 weeks
• negative carbon footprint
• tested safe up to F5 wind conditions - Miami Dade County approved
• fire rating of 2.5 hours
• delivers up to 13 LEEDS points - halfway to accredited status
• thermal envelope that is 7x tighter than traditional construction
• mold resistance verified by independent testing

Casey;

It was too good to be true ..............you need to read on in the ICC evaluation report that states you need a layer of drywall on each side just to obtain a 1hour rating

Casey;

also found that in order to get the 2-1/2 rating for wall only you need the 7-3/8" thick wall and drywall each side

Their Miami -Dade is for walls only , not roof

Thanks, Chris - I usually dig a little deeper but made the mistake of just skimming this one without probing beneath the marketing hype.

Just looked up R-Control SIP fire rating and for one hour:
Panels - R-Control SIPs consisting of a polystyrene foamed plastic
core faced on both surfaces with min 7/16 in. thick oriented strand
board. Min 5-3/8 in. thick polystyrene core.
Gypsum Board - 5/8 in. thick, 4 ft. wide, applied vertically
installed with 1-5/8 in. long high/low bugle-head steel screws spaced 8
in. OC along the edges and 12 in. OC in the field. Vertical joints over
vertical joints of Building Units* (Item 1). Gypsum Board joints covered
with joint tape and joint compound. Screw heads covered with joint
compound.
Plus a few other details ( http://www.pfscorporation.com/pdfs/chapter9appendixb.pdf )
(There are a couple of other assemblies for 1 hr, but they don't give a 2 hr.)
I did this pretty quickly so I might not have dotted all the i's and crossed all the t's on this one either...)

Again  - I am definitely not wedded to steel faced polyiso SIPS, so would still appreciate any suggestions for a superior approach - both structurally and cost-wise. 

There is an outfit in Canada called ATI Composites that claims to have have developed a non-flammable insulation that is suitable for SIPS but it appears that no one is using this yet  I sent them an email asking for any manufacturers but they never responded.
web site:  http://www.ati-composites.com/thermalbarrier.html

Do you have any thoughts as to why so few insulated panels utilize polyiso rather than EPS?  Cost, fabrication problems?

This is interesting because the usual goal is to protect a structure from an internal fire.

To protect from an external fire, concrete would seem to be the material of choice for the roof structure.  You may lose the membrane and any insulation on top of it in the circumstances you describe, but the structure should remain intact.  It seems that the green roof itself should provide a reasonable amount of protection from a fast moving brush fire.  Adding some addition soil thickness (say 2") may also provide some added peace of mind.

What will you use for the walls?  Are you insulating?  Cement board (or cement plaster) with an air space should provide protection.

There are also a variety of spray-on fireproofing products and  intumescent paints that can be used to protect the steel structure itself if needed.  Drywall cladding also works.

You might consult with your insurance company on this matter. 

Bruce

Casey;

we achieve the same 1 hour rating with our 4" panel and drywall, we do have a non-bearing 1 -hour mineral wool core panel that does not require any drywall ( it is good for tall interior party walls)

no matter what you use on the walls and roof , you still would need to overcome the overhead door and walk in doors for fire resistance

Bruce -
I am seriously thinking of surface bonded CMU with steel rebar/concrete fill for at least the first ten feet.  The back half of the shop will be set into a hillside to a depth of about 8' or 9'.  I would probably use a couple of inches of either rock wool or polyiso on the inside covered with cement board or something like Dens-Deck.  I would prefer to insulate outside the block, but this area is a carpenter ant convention center and I have had the ants chew their way into bats of pink fiberglass insulation and build a nest in there.  I assume they would consider foam a recreation area.  Not sure how they would like rock wool but I assume they would treat it much like the fiberglass insulation.  I might go with something like Faswall blocks (manufacturer 150 miles away) if I can afford it. 

Above the block, not sure.  Possibly non structural fire resistant SIPs or conventional construction with concrete board panels and insulation bats.  Still many decisions to make on materials and construction.  My budget is looking like I may have to make some compromises. 

For the roof, I had originally thought of going with some type of concrete panels but it seems like SIPs would be much lighter for the needed strength.  Adding weight to the roof rapidly increases the cost of the required steel supporting framework.  Again, I haven't settled on a design other than the steel frame and the green roof so suggestions for appropriate construction materials and methods are greatly appreciated. 

Casey;

I think we are missing the big picture here, we are talking about a weld shop?

You are contemplating going to great expense to save what?

..........clad with steel panels, insure it and if by chance a wild fire gets it collect the insurance and re-build

Chris -
My experience with insurance settlements is that you get a lot less than what it costs to replace the loss - particularly all the little bits and pieces that one doesn't really think about.  I am hoping to make this a reasonable place to work in 100 plus temperatures that we have in the summer, which will require some degree of insulation in the roof and walls.  I am hoping that I can get a fire resistant building for not too much more than a well constructed welding shop with a reasonable amount of insulation.  What I need to figure is how much more cost is involved with using steel SIPs vs regular sips with extra protection against water leakage vs laying down a conventional steel roof covered with polyiso insulation covered with roofing panels for strength covered with Dens-Shield for water resistance.   What I do know is that a traditional roof surface will not pass muster with the planning commission and normal insulation in this type of building does not make it comfortable to work in during sunny summer days or winter days when the mercury approaches zero degrees F.  

what about autoclaved aerated concrete

Jelly;

I agree autoclaved , floor and roof, but at what cost? and how to handle overhead door?

Adam, are you in New Orleans? I had no idea Xella/Hebel had a presence here.

Yes, I live in the New Orleans area and the sales manager for Louisiana, Mississippi, Alabama and big box stores. I noticed you are located in the Batonn Rouge area. Is there anything i can assist with?

We (Xella/Hebel) is currently serving the United States with two plants and as the economy increases our goal is to expand with more AAC plants throughout the USA.

A little late but a question: Everything stated so far are "passive" fire prevention techniques. Having seen videos of wet roof/wall wildfire protection sprinkler systems on TV, have you also considered an "active" system? You usually need to water a green roof for the first year or two anyway so why not install an expanded permanent system instead?