Archive for the ‘Fire Testing/Fire Resilience’ Category

Australian Fire and Straw

First of all, I want to extend a word or two of support and sympathy for our brothers and sisters down under as the fires of a heat wave have torn through their beautiful land. Having personal experience with wildfire, I know the challenges and hardships they can create. Several years ago, a roughly six thousand acre fire was stopped on my doorstep, literally. The crews were able to steer the flames and squash them down into a manageable slot and snuff them out just a few hundred feet from the front of my house. We were evacuated at the time, and I remember the impact of the flames and smoke on my family and my animals. I remember having elk in my field, something that does not happen around here, because the smoke had flushed them out of the higher elevations. I can imagine what our brothers and sisters in Australia are experiencing and I send my emotional support out.

Be sure to remember as these fires move through that straw bale homes are very safe in fire prone areas. They have a high level of fire resistance. They have been proven to resist fire much longer than conventional homes. When the impact, speed, and fierceness of wildfire comes knocking, it is comforting to know that a bale home can keep you and the ones you love safe. Of course, this is not to say that you could ride out a fire like the one shown above in a bale home, but that home will offer you more security against fire than a conventional home and that may just be the difference between saving or losing the ones you love.

Once again, I hope for rain and I send you thoughts of happiness and safety from up North.

Attic Vents and Wildfire

I live in the country and am quite aware of the places fires start: leaves under the deck, debris in foundation vents, trees not properly maintained near the house, etc. If you live in fire prone areas, be sure to read on about attic vents and wildfires.

wildfire_biscuit1.jpgDear Andrew,

My sister was an evacuee in the major San Diego Fire. She lives in Rancho Bernardo. She is an area coordinator for neighborhood watch. At the last meeting after the fire an attending fire captain explained an interesting phenomena many of the homes that were destroyed and had tile roofs had something happen to them that most other homes did not.

The fires started in the middle of the building not the out side. After a through investigation the fire dept. came up with two causes. The first was that homes that had curved tile roofs and did not have bird blocks embers blew between the tiles and started the roofs on fire under the tiles. The second cause was that older tile roof home had attic vents that had 1/4 ” mesh screen or larger and the embers just blew through the screens into the attic causing the fires. When the winds came through the Rancho Bernardo area they were around 40 to 60 mile an hour. It was like a blast furnace and temperatures in some areas exceeded 2000 degrees. With the wind blowing in a horizontal direction the heat and the winds blew embers and extremely hot air into the attics of the homes. The fire dept. is now recommending that new homes and older ones be fitted with attic vents of 1/8 ” to prevent small embers from being blown into the attics. The only problem here is that the mesh being extremely thin my also melt or burn at lower temperatures. You may want to pass this information on to Straw Bale Builders and run it
by your local fire dept.

 

Straw Bale Homes Protect Against Fire Where Conventional Homes Fail

house-fire.jpgWe have all seen images of the massive fires in Southern California. I would first like to send out my sympathy to anyone affected by the flames. I would also like to send out my respect and gratitude for the firefighters who risk their lives and give their all to defend the homes and lives of others. I have considered how to write about this topic over the last few days and I want to be clear that my intention is to support home owners in the affected areas, not judge them or tell them they have “done something wrong.” I want them to know about the incredible fire resistance of straw bale construction and how they can rebuild their homes with security built in. I have included a video at the end of this post which speaks to the fire wall testing data for straw bale walls.

Protecting against fires has long been important to code officials, builders, and home owners alike. None of us want to see our homes go up in flames. None of us want to experience the loss and the grief associated with that loss. Building codes exist to protect homeowners from fires: both minor and catastrophic. Even with those codes in place, we have seen that a well built house can burn to the ground in a matter of minutes. To me, the reason for this is obvious. A conventional stick framed home is nothing more than a series of chimneys behind a thin layer of fire protection. What many homeowners don’t know is that the majority of the fire protection required by code in a conventional home is in the form of drywall. That’s it! 1/2″ of gypsum board is all that is required to protect you from fire. Once that drywall barrier has been compromised, there is nothing to stop the fire from attacking the structural wood and/or steel framing in your home.
burnt-house.jpg
Straw bale homes are different. Straw bale houses are known for and have been tested to resist fire by up to three times that of conventional homes. Three times the protection may be the difference between a total loss and a miracle. The photo below shows how a home built of the right materials can survive even amongst completely destroyed homes built to conventional standards. I want to be clear that this photo is not of a straw bale home as I do not have a photo in my possession that shows what I am talking about; however, the data is the same. A house built with bales has up to three times the fire resistance of a conventionally framed house. The house in the following photo does have one thing in common with straw bale homes: it is plastered. This is the first line of defense for straw bale homes. The 1- 1/4″ of plaster provides far superior resistance to flame than most sidings. Imagine trying to burn your way through that much plaster.
fire_resistance.gif
The second, and often most surprising element of straw bales that increases the fire resistance is the bales themselves. When most people think about straw and how it performs in fire, they think about barn fires, spontaneous combustion, and other fire stories. The fact of the matter is that barn fires are caused by hay that was baled too early with high levels of moisture still in the crop. The fires start when that moisture creates heat by decomposing the hay and then the hay flares from the heat of the decomposition inside the bale. Straw is baled when the crop is dead and dry, usually around 8% moisture content by volume, so no interior decomposition occurs. Moreover, the bales are so tight, that most of the oxygen has been squeezed out of them. Fire cannot exist without oxygen, so once again the bales have created a form of protection against flame spread. Consider that a bale is like a phone book. If you rip out the pages one by one and light them on fire, they will burn: so will loose straw (although not very well due to the high silica content). If you hold a lighter under the entire phone book, however, you will likely run out of fuel in the lighter before the book catches fire because there is no oxygen in between the pages to support the flame. The same is true for the baled straw. Now put the two systems together: thick plaster on both sides of the wall and dense, oxygen deprived bales inside. This combination makes for a very resistant wall and one which has a much better chance of survival in fire situations. Protecting your home from fire in other ways is still important. Be sure to clear brush from around your house, clean out your gutters and under your decks, and so on. There are several sites which offer guidance on how to protect yourself from wildfires. If you live in a fire prone area, I strongly recommend that you complete the steps outlined on those sites.

The above video talks about some relatively recent fire testing on straw bale walls. The results of the testing were very positive and support everything that I have said about straw bale walls and their fire resistance. My want is for people who live in fire prone areas to start getting serious about protecting themselves from fire. Thousands of homes and buildings have been destroyed in the last two weeks by the wild fires in Southern California. Most of the people who lost their homes will rebuild. I challenge them to build with bales instead of building another conventional home. The benefits go beyond fire protection and reach into the world of green construction and healthy homes. But for this conversation, consider the difference between a total loss and a miracle the next time the fires comes blowing through…which they will!

More on Fire Ratings

This is a response to a comment about bale buildings and their ability to resist fire. The author of the original email challenged the fact that conventional buildings only have a twenty minute burn time and that they do not actually have a chimney affect like I describe. I disagree and you can see my response below.

Thanks for your email. What I refer to in the twenty minute burn time is the rating of the drywall. A standard wall assembly is designed to resist fire for 20 minutes and then the drywall will be burned through. Once in side the drywall, you do have chimneys, albeit small ones that run for at most 10′ and at least 8′. Fire blocking is not required until you reach ten feet in height and wood plates at 8′ or 9′ are the standard in most homes. Consider a “chimney” of 1/2″ drywall (one break in the drywall will allow the flames in), dry 2×6 studs 1 1/4″ of plaster on top of densely packed, silicone rich material with extremely low amounts of oxygen in the material. This is where the comparison is a clear winner for bale building.

The recent fire testing results support this claim. I have seen conventional homes on fire and they get out of control very quickly. In contrast, a plastered bale home will smolder for a long time before any flames actually take hold. That’s where I am coming from on this. I know it seems counter intuitive to think bale homes could last longer than conventional homes when faced with fire, but that is what I have seen and what the studies have shown. Thanks again for your email.

Fireplaces in Bale Walls

It is very common for home owners to want a fireplace these days and the addition of flames into a straw bale wall assembly is often a cause for concern to the local building inspector. Most of today’s stoves, either direct vent gas units or wood units, are designed to have minimal clearance around them to flammable materials.

In “the old days” a fireplace emitted a lot of heat all the way around the unit and needed to be greatly isolated from the walls or surrounded with a non flammable protective layer of brick or stone. Today’s units can have as little as a few inches separation from flammable materials because the majority of the heat is directed forward and/or up and the sides and back of the units do not get very hot at all. That said, it is still good practice to consider the risks of fire produced heat introduced into a bale wall assembly either at the unit or the stove pipe.

Another thing to consider when installing a fireplace unit is the difficulty of the installation. For this reason and for the reason described above, I install my units into a framed “faux” wall within the bales. In other words, I frame out a wall that is even with the face of the bales so that once it is covered in drywall and plastered, there will be no difference from the surrounding bale walls. This creates a simple installation for the unit and allows for the addition of a blower or other upgrade in the future. If the unit is installed directly into the bales, the addition of such upgrades in the future would be more difficult. The framed wall also creates space for the installation of the venting pipe and can also be used to create an entertainment shelf or plant shelf above the fire box. The last one we did had a beautiful cabinet above the fireplace which held a small TV for the master bedroom. The framing makes all of this easier.

Update on Straw Bale Projects and a Wall Street Journal Article About Straw Bale Wall Fire Testing

Sorry it has been so long since I last wrote. Things have been very busy around here with building and preparing all the paperwork necessary to start and fund the next four houses we will be building. We start the foundations of 2 next week, have one ready for baling, and one is a major remodel which starts with demolition in two weeks. We also have 2 more homes in the final design phase ready for bank funding next month. All in all, it is an exciting time. I recently received a copy of the article in the Wall Street Journal about the recent fire testing of straw bale wall assemblies. I have attached it here for you to read. The results of the fire testing will be up on the web for review by September. Keeps your eyes open for the report!

Will Insulating With Straw Catch Fire?

By ALEX FRANGOS

August 9, 2006; Page B1

IN A LABORATORY in Elmendorf, Texas, last month, workers fired up a super-hot gas furnace next to a wall stuffed with straw in hopes of calming skittish insurers, bankers and building inspectors who have been reluctant to embrace big buildings insulated with bales of dried grasses.

Things got off to an inauspicious start for Bruce King, the engineer and straw-bale construction fan who raised the $35,000 for the independent test. Within minutes of being exposed to the 1,700-degree heat, cracks developed in the fire-resistant plaster covering the wall, and the straw inside began to char. But after two hours, the other side of the wall was unscathed. Then, it survived the second part of the industry-standard test for building-material safety, a high-pressure soaking from a fire hose.

“It opens the doors to every realm of construction,” says Mr. King, who operates a straw-bale advocacy Web site and is writing a book on the construction material.

So far, a 1980s revival of straw-bale construction — which originated in the 1890s on the arid plains of Nebraska where the ground was too dry for settlers to build from sod — has been limited to survivalists and high-end, eco-oriented homeowners. There aren’t any official measures of the number of straw-bale buildings, but advocates estimate there are several thousand in the U.S., most of them single-family homes. But now, responding to the demand for more so-called green buildings, architects and builders are starting to use dried rice and wheat stalks in larger, more public facilities such as schools, churches, wineries and transit facilities. There, the building standards — and potential consequences of a fire — are much higher than a single-family home.

Straw proponents believe the successful fire test will persuade more mainstream builders to use straw bales instead of the standard fiberglass or foam insulation.

In the absence of a fire test, most insurers have balked at straw-bale construction, according to the Insurance Information Institute, a trade group. American Family Insurance, for example, refuses to cover it at all. “We have concerns with how these homes would hold up in loss situation involving fire smoke and water,” says Steve Witmer, spokesman for the Madison, Wisc., company. “There’s also cost factors stemming from limited experience from contractors in repairing these types of homes. And we’re not sure about the availability of building materials.”

Straw-bale buildings look similar to other buildings, though they have two-foot thick exterior walls covered in a stucco-like plaster, often giving them a Southwestern adobe feel with thick curved walls. In most cases, as in traditional construction, wood or steel beams carry the weight of buildings’ floors and roofs. The bales are inserted between the studs or beams. Chainsaw-wielding workers trim the straw to fit electrical boxes or architectural features such as curves in the wall. A thick coat of plaster covers the bales, keeping them dry and protecting them from fire.

Inch for inch, straw bales insulate about the same as fiberglass, but because they are so much thicker than typical rolls of insulation, they provide a stronger shield against heat and cold. Straw bales often are procured from local farms, reducing pollution that comes from transporting construction materials, a key concern of green-building advocates. Straw is also easier to dispose of because it’s biodegradable. A small house would use 150 to 300 bales.

The walls of a transit building in Santa Clarita, Calif., are insulated with straw bales and covered with lime plaster. Designed as a demonstration project for eco-friendly building, there were some problems during construction because of the novelty of the materials, but the architect says it has performed well since opening in April.

Architects who’ve worked with both forms of insulation say the cost of using straw bales instead of fiberglass can be about the same to 10% more. While the actual bales cost less than industrial-made fiberglass insulation, labor costs can be higher because contractors aren’t accustomed to it. A 24-by-16-by-48-inch bale costs about $3.

The fiberglass-insulation industry doesn’t sound worried that straw bales could usurp its place between the walls of buildings. “It’s a very specific niche of the market versus being used by big production builders,” says Robin Bectel, spokeswoman for the Virginia-based North American Insulation Manufacturers Association.

But straw bales are beginning to be found in larger projects nationwide. The Friends Community School in College Park, Md., is building its new schoolhouse with straw bales. The school for 165 kindergarten-through-8th grade students is due to open this winter. Schools have traditionally been made of brick and steel to lower the fire risk. “We did the research,” says school head Tom Goss, referring to some nonofficial fire studies. “Straw bales operate like a mattress. They’re so compacted there’s no way for air to get in there.”

But parents had other concerns, he says. What about mice and rats? “We found out that straw doesn’t have food value,” says Mr. Goss. “It’s the equivalent of wood.” And since there are no seeds in straw, there are also no worries about allergies. The school will cost $5.7 million, not significantly more than if it were built using traditional wallboard with fiberglass insulation, says project architect Peter Doo of the Baltimore firm Hord Coplan Macht, Inc. Local building officials, who had some experience with straw-bale homes in the area, approved the school.

It was a different story for Aerzen USA Corp., an industrial-blower manufacturer in Coatesville, Penn. It wanted to use straw bales for a $3.5 million manufacturing warehouse and office, but a local building official didn’t want to approve the project without an official fire test. And to boot, the cost came in 10% over budget. “We can’t charge our customers 10% more so we can have a straw-bale building,” says Aerzen USA president Pierre Noack. The building, set to start construction soon, will still be eco-friendly, with lots of traditional insulation to conserve energy. “In the end, the bottom line wakes you up,” he says.

Building-safety officials are conflicted about the fire issue because making straw-insulated buildings fire-safe could make them vulnerable to another risk — water.

The Desert Living Center, owned by the Las Vegas Valley Water District, will be the largest straw-bale complex in the country when its five buildings open in 2007. When the architects submitted plans, the Las Vegas building department said because it had been designed with enough emergency exits, the center didn’t need fire sprinklers, even though buildings of its size usually require them. The officials feared that if the sprinklers were set off accidentally, the walls would get wet and need to be replaced. In the end, the local fire marshall insisted on having sprinklers. “That’s my biggest nightmare,” says Jeff Roberts, the project architect with Las Vegas architects Lucchesi, Galati Architects Inc. “If the walls got wet, they’d have to come down.”

Building with straw can pose other challenges. The city of Santa Clarita, Calif., wanted to use a $26 million transit-administration building as a straw-bale demonstration project. “The city saw this as a good opportunity to set the tone, to show local contractors who come in bellyaching about what it costs [to build green] to say, ‘Here, we did it,’” says Charles M. Smith, a vice president at Hellmuth, Obata and Kassabaum, the project’s architect.

Things didn’t go as planned. The straw-bale sub contractor and the architects fought over the design of a wall that supports a long span of windows. Outside experts had to be brought in to mediate. Then construction workers who had never worked around straw mistakenly removed 2 x 4s that kept the bales straight and climbed all over them, forcing the bales out of position, says Mr. Smith. An improperly installed drain on the roof let winter rains soak the bales before they had been plastered. Two-thirds of the bales got moldy and had to be replaced.

Still, the facility opened in April and is performing well, the architect says. “The lessons learned is that with straw bale, everything has to happen perfectly for it to go right,” says Mr. Smith. “But it turned out to be a beautiful building.”

Write to Alex Frangos at alex.frangos@wsj.com

Straw Bale and Fire Wall Testing

This video is from my online video newsletter called “The Straw Bale Minute”. It focuses on the fire testing on straw bale walls.

You can find all of my short videos on YouTube at http://www.strawbale.com/videos. Please check them out, rate them and leave comments. The more action these videos get, the faster they will move up the ladder. My goal is to get these free videos in front of as many people as possible.

Straw Bale Homes and a Wildfire

I received the following e-mail yesterday regarding the fire resistance of straw bale homes:

“I have a 10 year old straw bale house in Flagstaff, AZ. I heard that in the wildfires over the last few years that straw bale homes incinerated. Have you heard that?”

Here’s my reply:

Thanks for your email and you can take a deep breath of relief. No, that is absolutely not true.

Bale buildings are very fire resistant. In fact, a recent study proved what we bale builders have known for years: once plastered, bale buildings have an extremely long burn resistance, more so that conventional homes. The results of that test will be out soon and will be posted on our website in some capacity.

During the wild fires in San Diego a few years a go, there was a neighborhood that was completely destroyed. The only thing left standing, literally the only thing, was one straw bale wall. The bales were burned out, but the wall was still in place. Even cars and oven ranges were burnt away, but not the SB wall!

Be sure to take safety precautions seriously and clear debris away from your house, especially under decks and in any foundation vents. Clean your gutters of leaves, and trim your trees up and remove ladder fuels. If you have adequate fire safety guidelines met around your home, you will be fine, in fact more than fine. You will be safe in a super fire resistant
house! Doesn’t that feel better?

Straw Bale Wall Assemblies Pass Fire Testing

I received an email today from Bill Christensen, the proprietor of http://www.GreenBuilder.com. It holds some very exciting news on recent fire testing of straw bale wall assemblies. Of course, those of us building straw bale houses have known that they are extremely resistant to fire; however, now we have proof to back it up! Here is what Bill had to say:

“It’s my pleasure to announce that plastered straw bale walls have just passed two important fire tests.

Two walls were constructed at a building materials testing lab in San Antonio earlier this summer – one was built with poly-tied bales on edge and covered with two coats of hand-troweled cement/lime plaster over stucco mesh, intended to approximate an infill wall in a commercial or institutional (or residential) setting. The second wall was stacked flat, put under 600 pound per linear foot load, and shot with two coats of clay plaster, approximating load bearing residential construction. No mesh was used on this wall.

The cement/lime plastered wall easily passed the ASTM E-119 2-hour fire and hose stream test. Lab personnel told us they felt it probably would have made another hour easily.

Due to some cracking on the exterior (non-fire) side of the clay plastered wall which occurred while moving the wall up to the furnace, and having seen the fire side plaster on the cement/lime wall basically being held on only by the wire mesh for the majority of the second hour, and considering that a 2 hour rating is rarely required for residential construction, we chose to do the clay plastered wall for just a one hour test. It too passed.

The official test reports will be available in about two weeks on the www.ecobuildnetwork.org and www.DCAT.net websites. They will also be included in the appendix of Bruce King’s forthcoming book, ‘Design of Plastered Straw Bale Structures’ (due out in time for the ISBBC in Ontario in late September).

Next time some insurance company gives you a hard time about straw bale being a fire hazard, you have an answer for them.

Congrats to the team: Bruce King, David Eisenberg, Matts Myrhman, Ben Obregon, Frank Meyer, Kindra Welsh, Baron Cougar, Mike Atkinson, Paul Taylor, and yours truly.

Thanks also to CASBA, COSBA, SBAT, and the individual donors for their financial contributions, as well as to whatever foundation it was that Bruce King managed to get the grant from.”