Here Are More Examples of Concrete Construction and Fire Resistant Roofing  

My previous two columns about reducing your home’s vulnerability to wildfires generated a lot of reader response, providing even more to write about on this important subject.

Fire resistance is personal for Rita and me, since we live in a wood frame home backing to open space which would be ready fuel for a wildfire.

I’ve been told that following an 1863 fire, Denver passed an ordinance requiring masonry construction. Somewhere along the line, that requirement was dropped. I wouldn’t be surprised to see building codes changed once again restricting wood construction.

While there’s a trend toward requiring  fire suppression systems inside homes, they are designed to suppress fires which originate inside a home.  If a fire originates externally, such systems may be of limited effectiveness in saving a structure.

Last week I wrote about ICFs — insulated concrete forms. Concrete is poured into a form which has insulating EPS (expanded polystyrene) on each side. This produces a concrete wall which has insulation pre-installed on each side of it.

A couple readers made me aware of the opposite approach, a concrete wall in which the “sandwich” has concrete on the outside and the expanded polystyrene on the inside.

Reader Lynn Greene invited me to visit her home in Perry Park (see picture below), southwest of Castle Rock, which was built with Thermomass® walls and concrete floors developed by Composite Technologies Corporation of Boone, Iowa.

Lynn’s tenant told me that the energy costs peak out at about $70 per month to heat the house with radiant floor heating built into the concrete floors. That heat is provided by a high efficiency boiler using natural gas. Large south-facing windows provide a lot of free winter time heating. (Notice the large overhangs shading the south-facing windows in summer but not in the winter.)

The Thermomass walls were poured in place, less expensive and more attractive than walls built of uninsulated concrete block. It also allowed electrical and other conduits to be built into the walls instead of surface mounted afterward.

Another “sandwich” approach is sold by a company called RSG 3-D, but they create panels which are assembled onsite instead of being poured in place. Also, their polystyrene interiors (which are wider) have steel connectors instead of the plastic connectors used in the Thermomass walls. That reduces the insulating quality of the wall, since metal is a conductor.

Another reader reminded me that the making of concrete is a major source of carbon dioxide, a greenhouse gas. According to Wikipedia, “The cement industry is one of the two largest producers of carbon dioxide (CO2), creating up to 8% of worldwide man-made emissions of this gas, of which 50% is from the chemical process and 40% from burning fuel.”

Click here to read an article from The Guardian about the development of “green concrete” in Australia that sounds very promising. As you may know, “concrete is made from approximately 10% Portland cement, 3% supplementary cementitious inclusion (for example fly ash), 80% aggregates (such as gravel and sand), and 7% water.” Then it is reinforced with steel, which has its own huge carbon footprint.  By replacing the steel with recycled plastic, that impact is mitigated, and, according to article from The Guardian, the Australian company Wagners has created earth friendly concrete using blast furnace slag – an industrial waste from steel production – along with fly ash, a waste from coal power generation, as a replacement for Portland cement.

To make a concrete home truly resistant to wildfire, it is necessary to make the windows and doors and other openings fire resistant too. There is glass (with frames) rated for 20 to 180 minutes of fire resistance. See www.fireglass.com.

Lastly, one must deal with roofing. Another reader made me aware of the synthetic roofing by CeDUR which was installed on her Wheat Ridge home and which is also on Woody’s Wood-Fired Pizza:

It looks just like a wood shake roof and is installed the same way in individual shakes, but it has the highest rating of fire resistance (Class A), earning homeowners a substantial discount on their homeowners insurance. Learn more at www.cedur.com/fire-safety.

There are vents of all kinds not only on your roof but on soffits, foundations, eaves and gables, and they need to be protected from flying embers. Vulcan Vent sells vents for all those openings, “built to create a barrier against wind-blown embers and flames in the presence of intense heat.” Learn more about them at www.VulcanVents.com.

Last Week’s Fire Disaster Is a Wakeup Call for Building More Fire-Resistant Homes  

My column on Nov. 29, 2018, followed the wildfire that took out the entire town of Paradise, California.

Last week we experienced a similar tragedy in our northern suburbs of Superior and Louisville. The difference was that this fire was driven by hurricane force winds that are all too common along the foothills.

Those winds weren’t limited to that area, and it was clear to Rita and me that a spark on Lookout Mountain (to which our home backs) might well have led to a similar catastrophe for the city of Golden. There’s no way to stop a fire driven by such winds.

You probably noticed, as I did, that the fire spared some houses while completely consuming adjoining houses, so perhaps it’s possible to increase the chances of being one of those skipped houses in a future wind-driven wildfire. Was it just luck, or did those homes have any features that may have helped spare them?

Today I’ll describe some features that might increase the chances of a home being skipped.

In high wind or low, it’s important to recognize that fires spread from home to home primarily by wind-blown embers. You’ve probably heard of insurance companies requiring homes in the “wildland urban interface” to create a “defensible space” around them by removing trees and other combustibles within, say, 20 to 30 feet of the home.

Useful as that might be, it’s more important that burning embers from further away not land on combustible material such as dead leaves, shrubbery, a wood deck, or a shingle roof.

There’s a useful website on this topic, www.DisasterSafety.org/wildfire. One of the links on that website that you’ll find useful is “What to do if a wildfire is approaching your home.”

California is, understandably, a leader in researching and rating building materials based on their fire resistance. Cal-Fire’s 48-page handbook dated Dec. 14, 2021, lists construction materials in 7 categories: decking; exterior windows; exterior wall siding and sheathing; exterior doors; under-eave protection; vents; and non-wood roof covering/assemblies.

If I were to invest in making my own home more fire resistant (which I am seriously considering in the wake of last week’s fires), here are some of the things I would investigate;

Metal roofing: I like the look of what is called “stone-coated steel” roofing. It looks from a distance like wood shake roofing. There’s an HOA in south Jeffco which requires wood shake roofing, but it will allow this kind of metal roofing. (It does not allow the more commonly used composition shingle roofing.)

Roof sprinklers: I have often thought it would make sense to install sprinkler heads at strategic locations on my roof to wet the roof if a fire is approaching. I’m going to ask a plumber about this concept. Sprinklers that douse the exterior walls might also be a good idea. I found on Amazon a kit of 2 roof sprinklers with gutter, wall or fence mounting and 50 feet of hose for $179.95, but I   like the idea of permanent sprinkler heads with through-the-roof plumbing, which I think my HOA would find less objectionable.

Motorized rolling metal shutters: I have seen these installed on a few Jeffco homes. They’re marketed for privacy and security, but they completely cover the windows when lowered and would surely help protect against fire. Some such systems allow the shutters to be operated via an app on your smartphone. One vendor is www.SomfySystems.com. Think of this as another reason for having a home battery backup system (which we have ordered) in case of power failure.

Non-combustible siding: The most common siding being installed by local builders is “HardieBoard” from James Hardie. Although it can be mistaken for wood siding, it is actually a non-combustible fiber cement product. It’s only 1/4 inch thick, however, so it only provides short-term protection and does not qualify as fire resistant, so it matters what is underneath it. (Refer to that Cal-Fire handbook of siding products.)

Special attention should be paid to the underside of roof overhangs, balconies and decks, where flames can be trapped. Roof soffits in most homes have vents which combine with vents on the roof to circulate outside air through the attic.  Unfortunately, this design can also allow the introduction of wind-blown embers into the attic. One way to eliminate these vents is to do what Meritage Homes did in building Arvada’s Richards Farm subdivision. The insulation of those homes is closed-cell foam sprayed onto the underside of the roofs, rather than the more typical blown-in cellulose or fiberglass batts resting on the floor of the attic, as is found in most homes. The attic in such homes becomes conditioned (i.e., heated) space, eliminating the need for soffit and roof vents. Meritage probably didn’t consider that making the homes more energy efficient in this way had the added benefit of making them more resistant to ember intrusion in a wildfire.

In past columns, I have promoted the all-electric home for sustainability and health reasons, but last week’s fires have provided another reason for doing away with natural gas. A large number of homes that were not destroyed are nevertheless enduring days and possibly weeks without natural gas for heating during some bitterly cold days. If any of those homeowners had switched to heat pumps for space heating and for hot water (as I have recommended), they would not be affected by the long delay involved in restoring gas service to their neighborhood. That might be an additional inducement to make the switch away from natural gas.

Homeowners in that area are being urged to boil water, so they might consider buying a countertop induction burner, which can boil water in one or two minutes, versus 10 or more minutes on a conventional range. I found 110V models online for $49-79.

It is not uncommon for homes to have “safe rooms” to which homeowners can retreat in case of a home invasion. If such a room were constructed in a basement with cinderblock walls, a metal door, and a concrete-and-metal ceiling, it might double as a survival room in the event of a wildfire when evacuation is a risky alternative. Given the increase in tornadoes due to climate change, it could also serve as a tornado shelter.

Although I have not researched it, I would guess that taking some of these precautions — especially metal roofing and the rolling metal shutters — might help to reduce your insurance premiums, as well as to possibly save your life and property in case of wildfire. 

Readers Offer Suggestions on Making Homes More Resistant to Wildfires

I was pleased to get several responses to last week’s column on protecting homes from wildfires.

One reader suggested that building a house out of concrete might help.  While this is a good idea, remember that such a house would still have a roof and openings for windows and doors that would need to be made as fire-resistant as possible.

Another reader suggested installing outdoor smoke detectors, something that hit close to home with a friend of mine. She said that a firefighter once rang her doorbell to warn her of an approaching wildfire. The moment she opened the door she smelled the smoke, but she hadn’t smelled it when she was indoors. For that matter, why not cell-connect detectors in the forests?

That prompted me to wonder why building codes don’t require smoke detectors in attached garages, but only require that the walls, door and ceiling be fire-rated to extend the time it takes for a garage fire to penetrate the living quarters.

Lastly, one reader pointed out that in a firestorm no measures are likely to prevent a home from being consumed.  So true.

Keep the suggestions coming.  You can comment on this post or comment on the original post from last week.